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COVID-19 has affected surgical practice globally. Treating neurosurgical patients with the restrictions imposed by the pandemic is challenging in institutions with shared patient areas. The present study was performed to assess the changing patterns of neurosurgical cases, the efficacy of repeated testing before surgery, and the prevalence of COVID-19 in asymptomatic neurosurgical inpatients.Cases of non-trauma-related neurosurgical patients treated at the Postgraduate Institute of Medical Education and Research (PGIMER) before and during the COVID-19 pandemic were reviewed. During the pandemic, all patients underwent a nasopharyngeal swab reverse transcription-polymerase chain reaction test to detect COVID-19 at admission. Patients who needed immediate intervention were surgically treated following a single COVID-19 test, while stable patients who initially tested negative for COVID-19 were subjected to repeated testing at least 5 days after the first test and within 48 hours prior to the planned surgery. The COVID-19 positivity rate was compared with the local period prevalence. The number of patients who tested positive at the second test, following a negative first test, was used to determine the probable number of people who could have become infected during the surgical procedure without second testing.Of the total 1769 non-trauma-related neurosurgical patients included in this study, a mean of 337.2 patients underwent surgery per month before COVID-19, while a mean of 184.2 patients (54.6% of pre-COVID-19 capacity) underwent surgery per month during the pandemic period, when COVID-19 cases were on the rise in India. There was a significant increase in the proportion of patients undergoing surgery for a ruptured aneurysm, stroke, hydrocephalus, and cerebellar tumors, while the number of patients seeking surgery for chronic benign diseases declined. At the first COVID-19 test, 4 patients (0.48%) tested were found to have the disease, a proportion 3.7 times greater than that found in the local community. An additional 5 patients tested positive at the time of the second COVID-19 test, resulting in an overall inpatient period prevalence of 1%, in contrast to a 0.2% national cumulative caseload. It is possible that COVID-19 was prevented in approximately 67.4 people every month by using double testing.COVID-19 has changed the pattern of neurosurgical procedures, with acute cases dominating the practice. Despite the fact that the pandemic has not yet reached its peak in India, COVID-19 has been detected 3.7 times more often in asymptomatic neurosurgical inpatients than in the local community, even with single testing. Double testing displays an incremental value by disclosing COVID-19 overall in 1 in 100 inpatients and thus averting its spread through neurosurgical services.

Background Preliminary data suggest that Coronavirus Disease-2019 (COVID-19) is associated with hypercoagulability and neurovascular events, but data on outcomes is limited. Objective To report the clinical course and outcomes of a case series of COVID-19 patients with a variety of cerebrovascular events. Methods We performed a multicentric, retrospective chart review at our three academic tertiary care hospitals, and identified all COVID-19 patients with cerebrovascular events requiring neuro-intensive care and/or neurosurgical consultation. Results We identified 26 patients between March 1 and May 24, 2020, of whom 12 (46%) died. The most common event was a large-vessel occlusion (LVO) in 15 patients (58%), among whom 8 died (8/15, 53%). A total of 9 LVO patients underwent mechanical thrombectomy, of whom 5 died (5/9, 56%). A total of 7 patients (27%) presented with intracranial hemorrhage. Of the remaining patients, 2 had small-vessel occlusions, 1 had cerebral venous sinus thrombosis, and another had a vertebral artery dissection. Acute Respiratory Distress Syndrome occurred in 8 patients, of whom 7 died. Mortalities had a higher D-dimer on admission (mean 20 963 ng/mL) than survivors (mean 3172 ng/mL). Admission Glasgow Coma Scale (GCS) score was poor among mortalities (median 7), whereas survivors had a favorable GCS at presentation (median 14) and at discharge (median 14). Conclusion COVID-19 may be associated with hemorrhage as well as ischemia, and prognosis appears poorer than expected-particularly among LVO cases, where outcome remained poor despite mechanical thrombectomy. However, a favorable neurological condition on admission and lower D-dimer may indicate a better outcome.

The COVID-19 pandemic has not only had a negative impact on people's health and life behavior, but also on economies around the world. At the same time, laboratories and institutions are working hard to obtain a COVID-19 vaccine, which we hope will be available soon. However, there has been no assessment of whether an individual and society value ​​a vaccine monetarily, and what factors determine this value. Therefore, the objective of this research was to estimate the individual's willingness to pay (WTP) for a hypothetical COVID-19 vaccine and, at the same time, find the main factors that determine this valuation. For this, we used the contingent valuation approach, in its single and double-bounded dichotomous choice format, which was based on a hypothetical market for a vaccine. The sample used was obtained through an online survey of n = 566 individuals from Chile. The main results showed that the WTP depends on the preexistence of chronic disease (p≤0.05), knowledge of COVID-19 (p≤0.05), being sick with COVID-19 (p≤0.05), perception of government performance (p≤0.01), employment status (p≤0.01), income (p≤0.01), health care (p≤0.05), adaptation to quarantine with children at home (p≤0.01) and whether the person has recovered from COVID-19 (p≤0.10). According to our discrete choice model in double-bounded dichotomous format, it was concluded that the individuals' WTP is US$184.72 (CI: 165.52-203.92; p 0.01). This implies a social valuation of approximately US$2232 million, corresponding to 1.09% of the GNP per capita.

No currently available literature evaluates the effect of Achilles tendon repair on professional baseball players in the Major League Baseball (MLB).The purpose of this study was to determine the impact of Achilles tendon rupture and repair on MLB players in terms of return to play and batting/fielding performance metrics.Achilles tendon rupture data were retrospectively collected using information from the MLB disabled list, injury reports, MLB game summaries, player profiles, and publicly available news articles. Four pair-matched control MLB position players were selected for each of the players who underwent advanced analysis. Baseline characteristics were compared between injured players and controls using Fisher's exact or Student'sOverall, the incidence of Achilles tendon rupture reported in MLB has increased substantially since 1996. Rate of return to play in MLB after Achilles tendon rupture and repair is 62% for position players (non-pitchers) who suffer the injury. There was no association of injury with any player metric. Compared with injury to the non-power side, injury to the power side was associated with fewer plate appearances, fewer triples, an increase in percentage of at-bats with strikeouts, and decreased speed score.The incidence of Achilles tendon rupture in MLB has increased substantially since 1996. While comparison suggests that overall Achilles tendon injury does not have an effect on MLB player statistics in the years following surgical repair, subset analysis of injury to the rear (power-generating) leg may lead to a decline in those statistics which denote a player's speed and running ability.

In response to DeSantis et al., we describe that the presence of phylogenetic signal in tooth wear dietary niche proxies is likely a result of the evolutionary process. We also address their concerns regarding enforcement of the use of phylogenetic comparative methods by editors of ecology and evolution journals.

Although metal-on-metal (MoM) bearing surfaces provide low rates of volumetric wear and increased stability, evidence suggests that certain MoM hip arthroplasties have high rates of complication and failure. Some evidence indicates that women have higher rates of failure compared with men; however, the orthopaedic literature as a whole has poorly reported such complications stratified by gender.This systematic review aimed to: (1) compare the rate of adverse local tissue reaction (ALTR); (2) dislocation; (3) aseptic loosening; and (4) revision between men and women undergoing primary MoM hip resurfacing arthroplasty (HRA).Systematic MEDLINE and EMBASE searches identified all level I to III articles published in peer-reviewed journals, reporting on the outcomes of interest, for MoM HRA. Articles were limited to those with 2-year followup that reported outcomes by gender. Ten articles met inclusion criteria. Study quality was evaluated using the Modified Coleman Methodology Score; the overall quality was poor. Heterogeneity and bias were analyzed using a Mantel-Haenszel statistical method.Women demonstrated an increased odds of developing ALTR (odds ratio [OR], 5.70 [2.71-11.98]; p0.001), dislocation (OR, 3.04 [1.2-7.5], p=0.02), aseptic loosening (OR, 3.18 [2.21-4.58], p0.001), and revision (OR, 2.50 [2.25-2.78], p0.001) after primary MoM HRA.A systematic review of the currently available literature reveals a higher rate of complications (ALTR, dislocation, aseptic loosening, and revision) after MoM HRA in women compared with men. Although femoral head size has been frequently implicated as a prime factor in the higher rate of complication in women, further research is necessary to specifically probe this relationship. Retrospective studies of data available (eg, registry data) should be undertaken, and moving forward studies should report outcomes by gender (particularly complications).Level III, therapeutic study.

How much does the Addiction-Like Eating Behavior Scale add to the debate regarding food versus eating addictions?

W e thank Dr. Wyland and appreciate his interest in our study. We would like to respond to the concerns raised in his letter to the editor [2]. We agree with Dr. Wyland that reporting the outcome in five separate subscales (symptoms; pain; function, daily living; function, sports and recreational activities; quality of life), enhances interpretation. However, as stated by Roos and colleagues [7], even though it makes it impossible to closely monitor the stages of rehabilitation, the calculation of a total KOOS score can show an improvement. Due to the fact that our objective was to report the general patient-relevant outcome at a minimum of 6 months postoperatively (and not to optimize rehabilitation), we decided to report a single score in this initial retrospective case series. Dr. Wyland noted that ‘‘the grading system described by Mitsou et al. and previously by Tegner actually evaluated the success of ACL reconstruction, not knee osteoarthritis treatments.’’ Due to lack of a specific patient-reported outcome score for treatment evaluation of subchondral bone marrow edema lesions, we decided to use the Tegner-Lysholm Score which, as correctly stated by Dr. Wyland, was initially developed and validated for ACL injuries. The rationale behind our decision lies in the fact that in up to 80% of ACL-ruptured knees, bone marrow edema lesions are present [3, 4]. We also feel that the critique by Bengsston and colleagues [1] on the sensitivity of the Tegner Lysholm Score regarding ACL injuries and other lower extremity conditions corroborates as opposed to discredits our choice. The grading of the score allows a more critical analysis of the outcome [1]. Dr. Wyland also correctly noted that ‘‘... there was no discussion of surgical revisions in evaluating clinical failure or surgeon learning curve, which one would expect to influence failure rates.’’ Within the confines of manuscript length, we reported the followup data that was available for this retrospective study; none of the patients had revisions. However, three patients were lost to followup. Also, the minimum followup to be included in this (RE: Chatterjee D, McGee A, Strauss E, Youm T, Jazrawi L. Subchondral calcium phosphate is ineffective for bone marrow edema lesions in adults with advanced osteoarthritis. Clin Orthop Relat Res. 2015;473:2334–2342). Each author certifies that he or she, or a member of his or her immediate family, has no funding or commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. The opinions expressed are those of the writers, and do not reflect the opinion or policy of CORR or The Association of Bone and Joint Surgeons. D. Chatterjee MD (&), A. McGee MD, E. Strauss MD, T. Youm MD, L. Jazrawi MD Orthopaedic Surgery, NYU Langone Medical Center, 333 East 38th Street 4th Floor, New York, NY 10016, USA e-mail: Dipal.Chatterjee@nyumc.org; dipal.chatterjee@gmail.com Reply to Letter to the Editor Published online: 24 September 2015 The Association of Bone and Joint Surgeons1 2015

CCAAT/enhancer binding protein alpha (CEBPA) mutations in AML are associated with favourable prognosis and are divided into N- and C-terminal mutations. The majority of AML patients have both types of mutations. We assessed the prognostic significance of single (n=7) and double (n=12) CEBPA mutations among 224 AML patients. Double CEBPA mutations conferred a decisively favourable overall (P=0.006) and disease-free survival (P=0.013). However, clinical outcome of patients with single CEBPA mutations was not different from CEBPA wild-type patients. In a multivariable analysis, only double -- but not single -- CEBPA mutations were identified as independent prognostic factors. These findings indicate heterogeneity within AML patients with CEBPA mutations.

The recent publication by Aly et al. [1] further confirms our conclusion that ultrasound-guided percutaneous tenotomy of the long head of the biceps tendon is feasible. Our paper was accepted for publication in April 2014 [2], and the Aly et al. paper was accepted for publication in June 2014. Since we had no previous knowledge of their study, we could not reference it in our paper. However, they describe a similar technique and results to ours using an arthroscopic hook blade, with a deep to superficial approach in the cadavers, which successfully resulted in complete tendon transection and no evidence of iatrogenic injury. We are the first to describe this procedure successfully performed on a live subject. Both the Aly et al. and the Levy et al. [3] studies show that the use of size 11 blade scalpels, banana blades, and retractable serrated blades results in incomplete transections of the tendons, as well as iatrogenic lesions of the cartilage, supraspinatus tendon, and subscapularis tendon. This further supports our conclusion that hook blades are the ideal instruments to obtain successful results of complete tendon transection, without iatrogenic injury. We concur that future long-term comparative studies of US-guided percutaneous tenotomy procedures are necessary to determine the efficacy of the procedure.

W e would like to support the interesting conclusions from a systematic review recently presented by Schlatterer and colleagues [1]. Their study addresses treatment for Grade IIIB tibial fractures and points to negative pressure wound therapy as an option that is changing the way many traumatologists think about the treatment of these difficult-to-manage wounds. As Schlatterer and colleagues point out, some clinicians support wound closure or stable muscle flap coverage within 72 hours to limit complications. The authors, however, found evidence to suggest that negative pressure wound therapy can be performed safely beyond 72 hours without increasing the risk of infection. These complex wounds can cause terrible morbidity and constitute a public health problem for many centers [2]. Through the years, researchers have devised a hierarchy of procedures within a hypothetical reconstructive ladder to guide the surgical treatment of wounds. This traditional reconstructive ladder, in its various iterations, subsequently has become a paradigm that helps to inform the choice of closure method across an array of defects. Currently, the increased availability of negative pressure wound therapy has illuminated its key benefits, including faster granulation tissue formation, less periwound edema, decreased closure time, less-frequent dressing changes, control of bacterial proliferation, and potential cost reduction. Although Janis et al. [3] have now incorporated negative pressure wound therapy as a new step in the traditional reconstructive ladder, we are advocating a different approach. In our experience, a descent in the usual reconstructive ladder (that is, from flaps to skin grafts or primary closure) is feasible if neoadjuvant negative pressure wound therapy is applied in the course of treating some complex wounds. This downscaled approach was taken in 106 patients with complex wounds seen between February 2011 and August 2014. All patients were initially subjected to negative pressure wound therapy via VAC system (Kinetic Concepts Inc, San Antonio, TX, USA). In 90 patients whose wounds were measured, the average wound area was 87 cm. (RE: Schlatterer DR, Hirschfeld AG, Webb LX. Negative pressure wound therapy in grade IIIB tibial fractures: Fewer infections and fewer flap procedures? Clin Orthop Relat Res. 2015;473:1802–1811). The authors certify that they, or any member of their immediate families, have no commercial associations (eg, consultancies, stock ownership, equity interest, patent/ licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. The opinions expressed are those of the writers, and do not reflect the opinion or policy of CORR or The Association of Bone and Joint Surgeons. J. A. Farina Jr MD, PhD (&), C. E. F. de Almeida MD, PhD, E. G. S. C. Marques MD, J. L. G. Jorge MD, R. V. K. S. Lima MD Division of Plastic Surgery of Department of Surgery and Anatomy, Ribeirao Preto Medical School of University of Sao Paulo-Brazil, Av. Bandeirantes, 3900 Monte Alegre, Ribeirao Preto, Sao Paulo 14049-900, Brazil e-mail: jafarinajr@fmrp.usp.br Letter to the Editor Published online: 21 August 2015 The Association of Bone and Joint Surgeons1 2015

Sir, We read with interest the article by Loupakis et al (2013) entitled ‘Histopathologic evaluation of liver metastases from colorectal cancer in patients treated with FOLFOXIRI plus bevacizumab' published in the June 2013 issue of the British Journal of Cancer. This paper clearly underlines the positive impact of FOLFOXIRI plus bevacizumab, on the extent of both tumour regression and necrosis, in resected liver metastases from colorectal cancer (CRC). The authors conclude that the addition of bevacizumab leads to a high ‘histopathologic activity' as compared to FOLFOXIRI or XELOXIRI alone. These data are important as pathologic response is considered as a new outcome end point by some authors, representing a prognostic parameter and a marker of sensitivity to preoperative treatments (Rubbia-Brandt et al, 2007; Blazer et al, 2008). Indeed, the higher the histopathologic response, the longer the survival (Rubbia-Brandt et al, 2007; Blazer et al, 2008). In this setting, we would like to mention several points that may be clinically relevant. First of all, pathologic complete response (pCR) was defined, in the study by Loupakis et al (2013), as the absence of tumour cells replaced by fibrosis and/or necrosis. This pCR definition corresponds to the grade 0 of the classification proposed by Blazer et al (2008), which is based exclusively on the percentage of residual tumour cells whatever the type of regression. However, in the Tumour Regression Grade (TRG) classification as proposed by Rubbia-Brandt et al (2007), fibrosis, but not necrosis, is considered as a characteristic feature of cellular response. According to these authors, the necrosis seen in CRC liver metastases is linked to spontaneous evolution of the tumour, involving insufficient vascular supply, and not to the treatment itself, thus excluding this characteristic from the TRG. In contrast, Li Chang et al (2012) recently showed a particular type of necrosis, so-called ‘infarct-like necrosis' (ILN), characterised by large confluent areas of eosinophilic cytoplasmic remnants, located centrally within a lesion and surrounded by a rim of fibrosis with foamy macrophages (Li Chang et al, 2012). This necrosis is morphologically different from the so-called ‘dirty necrosis', usually seen in CRC, containing nuclear debris in a patchy distribution. In this study, ILN was only seen in preoperatively treated CRC liver metastases and never observed in untreated patients who underwent primary resection of CRC liver metastases. In addition, Li Chang et al (2012) also noticed that ILN was significantly associated with chemotherapy plus bevacizumab treatment, although this feature was not specific and was also encountered with chemotherapy alone. Moreover, progression-free survival and overall survival were longer in patients with CRC whose liver metastases showed ILN as compared with CRC patients whose metastases lacked this feature. Besides the well-designed work by Loupakis et al (2013), several studies concerning preoperative treatment of liver metastases have already reported a higher percentage of necrotic areas in tumours treated with bevacizumab (Klinger et al, 2010; Wicherts et al, 2011). However, the precise type of necrosis involved in tumour response was not reported. Our team recently confirmed the previous findings of Li Chang et al (2012), but on a larger population of bevacizumab-treated patients and in the setting of first-line metastatic treatment. We retrospectively reviewed archival liver CRC metastases from 91 patients who underwent secondary resection after preoperative treatment. On the basis of tumour availability, three group of patients with liver metastases were identified: a control group of chemonaive metastases (n=29), a group with metastases treated with chemotherapy (CT) alone (n=31) and a group with metastases treated with CT and bevacizumab (n=31). The frequency of ILN was statistically different among the three groups (P

Reply: Comment on ‘Allergy and acute leukaemia in children with Down syndrome: a population study. Report from the Mexican Inter-Institutional Group for the Identification of the Causes of Childhood Leukaemia (MIGICCL)’ – A reality or myth or two viewpoints about the association between allergies and acute leukaemia in Down syndrome children

Vaccination coverage is a widely used indicator of programme performance, measured by registries, routine administrative reports or household surveys. Because the population denominator and the reported number of vaccinations used in administrative estimates are often inaccurate, survey data are often considered to be more reliable. Many countries obtain survey data on vaccination coverage every 3-5years from large-scale multi-purpose survey programs. Additional surveys may be needed to evaluate coverage in Supplemental Immunization Activities such as measles or polio campaigns, or after major changes have occurred in the vaccination programme or its context. When a coverage survey is undertaken, rigorous statistical principles and field protocols should be followed to avoid selection bias and information bias. This requires substantial time, expertise and resources hence the role of vaccination coverage surveys in programme monitoring needs to be carefully defined. At times, programmatic monitoring may be more appropriate and provides data to guide program improvement. Practical field methods such as health facility-based assessments can evaluate multiple aspects of service provision, costs, coverage (among clinic attendees) and data quality. Similarly, purposeful sampling or censuses of specific populations can help local health workers evaluate their own performance and understand community attitudes, without trying to claim that the results are representative of the entire population. Administrative reports enable programme managers to do real-time monitoring, investigate potential problems and take timely remedial action, thus improvement of administrative estimates is of high priority. Most importantly, investment in collecting data needs to be complemented by investment in acting on results to improve performance.

Sir, We thank you for the response and valuable comments (Dieckmann, 2014). We appreciate your contribution by pointing out that, besides experimental data (Nuver et al, 2010), there is growing clinical evidence of acute cardiovascular toxicity of chemotherapy in TC patients, which is most likely based on vascular wall damage. Previous studies have suggested not only chronic atherosclerotic effects of chemotherapy for TC, but also more acute effects of thrombo-embolic origin (Dieckmann et al, 2010). The increased von Willebrand factor found in patients directly after chemotherapy contributes to the idea of acute vascular toxicity of chemotherapy (Dieckmann et al, 2011). It is indeed important for clinicians treating patients with TC, to appreciate the acute as well as the more chronic vascular effects of cisplatin-based chemotherapy.

Reply: Comment on ‘A derived neutrophil to lymphocyte ratio predicts clinical outcome in stage II and III colon cancer patients’

On behalf of my coauthors, I thank Singh et al. for their comments regarding our study [2]. We agree they have raised valid questions. We believe that traction or tethering effect on the nerve roots due to spinal cord shift occurring after spinal canal decompression is the cause of postoperative C5 palsy [4]. The rationale for choosing this technique is to preserve ligamentous attachments and bony posterior elements as much as possible to control posterior shift of spinal cord after suitable decompression, instead of excessive decompression. The mean improvement ratio of neurologic function (Japanese Orthopaedic Association score) was 59% at last followup in this study. Because we did not have a control group for this study, it is unclear whether the suitable decompression of hemilaminectomy decreases the degree of cord function compared to excessive decompression of laminectomy. It is true that the hemilaminectomy approach may provide a relatively narrow exposure of the spinal canal, but does more decompression lead to a better clinical result? The surgical results for multilevel continuous/mixed cervical ossification of posterior longitudinal ligament involves various aspects, including neurological function and complications (especially C5 palsy and kyphosis) at short- and long-term followup. Previous studies [1, 3] reported that unilateral fixation had comparable efficacy to bilateral fixation in lumbar spinal fusion. Unilateral fixation is one of the remarkable novel ideas of this technique. We performed contralateral fixation because it was convenient to perform bone grafting on this side, and there was sufficient bone graft bed to afford adequate stabilization of the cervical spine. Because the cervical spine was not unstable, we tried unilateral fixation after multilevel hemilaminectomy and found it was enough for stabilization of the cervical spine. Our last followup indicated a spinal fusion rate of 100%. There were no instances of pseudoarthrosis, rod breakage, or pullout of screws. Fixation on both sides may be more rigid, but unilateral fixation can be acceptable if the approach stabilizes the cervical spine. Future research studying the long-term biomechanical outcomes of unilateral fixation is necessary. Thank you for highlighting some interesting issues relevant to this surgical technique.

Background: A phase III trial was conducted to determine whether neoadjuvant chemotherapy (NACT) before radical surgery (RS) improves overall survival. Methods: Patients with stage IB2, IIA2, or IIB squamous cell carcinoma of the uterine cervix were randomly assigned to receive either BOMP (bleomycin 7 mg days 1–5, vincristine 0.7 mg m−2 day 5, mitomycin 7 mg m−2 day 5, cisplatin 14 mg m−2 days 1–5, every 3 weeks for 2 to 4 cycles) plus RS (NACT group) or RS alone (RS group). Patients with pathological high-risk factors received postoperative radiotherapy (RT). The primary end point was overall survival. Results: A total of 134 patients were randomly assigned to treatment. This study was prematurely terminated at the first planned interim analysis because overall survival in the NACT group was inferior to that in the RS group. Patients who received postoperative RT were significantly lower in the NACT group (58%) than in the RS group (80% P=0.015). The 5-year overall survival was 70.0% in the NACT group and 74.4% in the RS group (P=0.85). Conclusion: Neoadjuvant chemotherapy with BOMP regimen before RS did not improve overall survival, but reduced the number of patients who received postoperative RT.

To the Editor: We read the article “Intramedullary Nails Result in More Reoperations Than Sliding Hip Screws in Two-part Intertrochanteric Fractures” by Matre et al. [3] with great interest, and we congratulate the authors for their valuable contribution to the orthopaedic literature. A fracture registration system database including more than 17,000 primary operations for hip fractures is a golden opportunity. The choice of implant for stable AO 31A1 fractures is a sliding hip screw and this is textbook knowledge [1, 2] that was confirmed by this article [3]. Another generally accepted piece of textbook knowledge is that the two disadvantages of intramedullary nails are local pain and fracture about the implant [2]. Matre et al. also confirmed this by reporting the two major reasons for increased reoperations for intramedullary nails other than sliding hip screws were local pain from the implant and fracture around the implant (with p values of 0.043 and 0.027, respectively; Table 4 [3]). Another statistically significant difference was the risk of implant removal (p = 0.028), which was lower for sliding hip screws. In their article, Matre et al. discussed the limitations of their database, and stated that they did not have the radiographs of the patients in their register. However, we believe analyzing the reasons for reoperations by depending on the radiographic images and file records (at least the failures of osteosynthesis, nonunions, cutouts, fractures around implants, and pain) would be important. In Table 4 [3], it shows there were 249 reoperations, including 189 sliding hip screws and 60 intramedullary nails. If the authors are able to review the x-rays and file records of a reasonable number of patients, perhaps as the subject of a new article, they might discuss the tip apex distance, position of the lag screw, reasons for the observed failures, pain, infection, and other reasons leading to reoperations, which we believe would be valuable contributions to the literature, and in particular would help us to distinguish implant-related from surgeon-related causes of reoperations.

I appreciate and agree with the comments shared by Rohman and Boddice regarding the expanding library of useful orthopaedic applications. In fact, since the initial publication of “Smartphone apps for Orthopaedic Surgeons” in July 2011 [3], much has changed in the realm of available orthopaedic apps. A followup study specifically examining iPad apps [4] and another review of orthopaedic apps [1] were published. I and others are continuing to examine the role that mobile technology will play in the lives of orthopaedic surgeons and patients. Rohman and Boddice identified an important concept: that the world of apps is in a state of constant change. With this in mind I launched www.TopOrthoApps.com in December 2011 to serve as a continuously updated resource of orthopaedic mobile apps. The site currently includes more than 200 apps for iPhone, iPad, and Android devices, a substantial increase from the 74 apps identified for my original article just 18 months ago. The website includes a listing of peer-reviewed apps and current literature on the topic of orthopaedic applications. In addition, the recent release of the “Top Ortho” app from the iTunes App Store (https://itunes.apple.com/us/app/toportho/id553738826?mt=8) now allows users to read reviews and download apps directly from their mobile devices. I also appreciate the authors’ mention of many newer apps and general surgical and anatomy apps that were not included in the initial review. To expand on their list, it is worth mentioning new educational resource apps such as AAOS eBooks, a plethora of online journals (Spine, Journal of Hand Surgery, JBJS Image Quiz, Journal of Orthopaedic Trauma, etc), TraumaLine, and EBSS.Live from AO. There also exist new reference and decision-management apps, such as OrthoRef, Septic Hip, SLIC, and eSplint. Newer apps have been released that focus on patient information and education, including the “Decide” series (SpineDecide, HandDecide, FootDecide, KneeDecide, etc) and DrawMD Orthopedics. Some publications [5, 7, 8, 11–13, 15] have started validating particular apps, which to this point have focused mostly on goniometer-based devices for angular measurements (ie, simple gait or function analysis measures). Finally, the number of nonEnglish apps has been increasing and currently includes apps such as OmbroCotov, OrtoClas, and TumorOsseo (Portuguese). With the prevalence and use of clinical apps on the rise, concerns have increased regarding app validation [6, 10], the risk of decreased hand hygiene [2, 14], confidentiality [9], and physician distraction [16]. Ultimately it is the responsibility of the physician to make decisions based on appropriate medical information and to ensure the safety of his or her patients. I encourage all providers to consider how apps influence their own practice and to remain diligent about ensuring patient safety and care.

Sir, We read with interest the findings presented by Muller et al (2012) evaluating associations between second to fourth digit ratio (2D : 4D) and breast cancer risk in a cohort in Melbourne. They reported a modest positive association between left 2D : 4D and breast cancer risk. They also observed an inverse association for Δr−l, which is the difference between right and left 2D : 4D, particularly for poorly or undifferentiated tumours. We were concerned that the authors focused on the Δr−l marker in their interpretations, as this marker has a lower reliability than 2D : 4D. At the same time, the 2D : 4D ratio has lower reliability than finger lengths. This is understandable, as the ratio is a computed variable of two-digit lengths, and thus their associated uncertainty is propagated following a specific function of both variables. Therefore, Δr−l contains the error associated to both right and left 2D : 4D ratios. The authors showed results on their measurement reliability in respect to digit lengths and 2D : 4D ratios, but not for Δr−l, although they based their conclusions on this marker. We previously conducted a validation study of these traits in the framework of an ongoing case–control study with more than 10 000 recruited participants. We assessed the reliability of these measures using a physical direct method with calipers, and compared it with those determined using a computer-assisted analysis on scanned images in 50 subjects. We found similar results than Muller et al in regard to digit lengths and ratios reliability. However, intraclass correlation coefficients (ICCs) for Δr−l were lower than 0.50, and variability owing to individual differences was around 30%. These results were observed for both direct and scan method, being even lower for women. These observations mean that only 30% of the Δr−l variation was produced by real differences between subjects. Allaway et al (2009) showed that ratios using the scan method with computer-assisted analysis presented slightly higher ICCs than those using photocopies. Thereby, it is expectable that the results we observed for Δr−l could be obtained using photocopies, which is the method that was used in the Melbourne cohort. Same results have been described previously by Voracek et al (2007), who found ‘ICCs unacceptably low (mostly less than 0.5)' for Δr−l, and remarked that ‘the direction and magnitude of the sex effect changed erratically across investigators'. Hopefully, misclassification will be non-differential between cases and controls, what would reinforce Muller's findings as this situation usually produce bias towards the null. However, if the exposure variable has more than two levels, like it is the case, bias away from the null may be present (Rothman et al, 2008). In conclusion, based on the previous observations, we believe that detailed information on the reliability of these measurements is needed in studies reporting associations with cancer risk, in particular specifying the variance components for all the markers involved.

To the Editor We read with interest the article by Shi et al. [9] published in your journal that addresses the controversial topic of percutaneous vertebroplasty (PVP) using meta-analysis of selected literature. The authors’ conclusion [9] appears to contradict Recommendation 8 of the American Academy of Orthopaedic Surgeons (AAOS) “Clinical Practice Guideline (CPG) on the Treatment of Symptomatic Osteoporotic Spinal Compression Fractures” [2]. We would like to address the differences between their analysis and that done by the AAOS CPG Workgroup. Although the meta-analysis process was similar in both reviews, some methodologic aspects differ. AAOS established a priori content based inclusion and exclusion criteria for study selection [2]. It is unclear how Shi et al. determined which articles to include. The AAOS Workgroup excluded three studies that they included [1, 4, 8] for poor study design description and for not being the best available evidence. A study is not the best available evidence if there are at least two studies of higher quality that measure the same outcomes; high quality studies are unlikely to be overturned by future evidence. Three studies in the current review [5, 7, 11] were published after the AAOS CPG was completed, but would not have changed our recommendation. Only three studies were mutually included [3, 6, 10]. Both reviews show no difference between sham treatments and PVP [2, 9]. There is disagreement in outcomes between nonoperative therapy and PVP, a comparison not made in randomized controlled studies because of inherent bias. The AAOS considered the magnitude of treatment effects by using statistical significance in the context of minimal clinically important improvements (MCII). The MCII is the smallest change that is important to patients; it controls for statistically significant treatment effects that are too small to matter. Shi et al. appear to incorporate only statistics. They rely heavily on the results of PVP that measure subjective outcomes and, in their conclusion, diminish the validity of comparing PVP with nonoperative treatment [9]. The meta-analysis by Shi et al. offers a different conclusion on the benefits of PVP than does the AAOS guideline. The methodology used by the AAOS is substantially more rigorous and transparent. Additional studies used in the Shi et al. analysis either do not meet our inclusion criteria standards or their weakened quality would exclude them in the AAOS analysis. We believe the AAOS’s use of MCII is preferred over the use of straight statistical comparisons used by Shi et al. PVP versus sham surgery is the gold standard of comparisons, and these results are not contradicted. It is understandable that physicians would want to validate a procedure that they believe works. For this to occur, high-quality studies using appropriate outcome measures will have to show a difference greater than the MCII.

We appreciate the thoughtful comments of Dr. Berger regarding our recent publication [1]. He focused on the following methodologic points: randomization methods, concealment of allocations, and masking (blinding). Overall, we are in agreement with the position that every action should be taken to minimize susceptibility to bias by using the most appropriate methods for conducting randomized controlled trials. However, we are concerned that theoretical judgments were proposed by Dr. Berger without detailed review of the actual studies being evaluated. Specifically, he argues that “in point of fact, it is unlikely that any of the studies were properly randomized, or enjoyed the benefits of allocation concealment”. In addition, he stated “it is unlikely that even the one study [2] that claimed masking could have been truly masked”. We should start by examining the specific methods used in the excellent study by Brushoj et al. [2] as an example. With respect to randomization, each subject was randomly divided into a group performing the prevention training program or a group performing the placebo training program using a stochastic computer-generated method. With respect to allocation concealment, group assignment was performed (according to personal registration number) by the head nurse who maintained the allocation sequence and who otherwise did not participate in the study. With respect to masking, the subjects and program instructors did not know which of the training programs was being tested. All subjects with knee or shin pain were examined by one of the authors who was blinded to training group allocation. Data were entered in a blinded manner from coded collection forms. In light of these actual methods, we are interested in comments and direction from Dr. Berger on how to better design, conduct, and report randomization, allocation concealment, and masking in future orthopaedic prevention studies.

Dr. Ali raises important and valid points. The medical profession should lead quality improvement efforts in health care, and the primary vehicles for change in our healthcare delivery system will be healthcare professionals. Expecting the dissemination of cost and quality reports to correct the information asymmetry in healthcare markets in a manner that equips patients to independently make informed value-conscious medical decisions is unrealistic and overly simplified. However, this was not the premise underlying our recommendation for public reporting of cost and quality information [4]. In the text of our article, we state that “The policy goals of reporting quality and cost information in orthopaedic surgery are to equip stakeholders, including healthcare purchasers, payers, and patients, with information to evaluate the relative value of musculoskeletal care. Correlating surgical outcomes with the costs associated with the delivery of surgical care holds the potential of yielding the measure of value desired” [4]. The underlying assumption is that the availability of cost and quality information will equip a multitude of actors to make more informed decisions, to increase provider accountability, and to incentivize performance improvement, more effectively than they can in the absence of such information. If appropriately implemented and applied, the provision and use of publicly available cost and quality information should gradually make it impossible for “failing providers” to provide care, and should equip patients to recognize what substandard care would be. Thus to the point raised concerning the possibility that “failing providers are left for those unable to exercise choice, for example, those in lower socioeconomic classes or the elderly”, the goal of public reporting in health care is to not allow such providers to practice without accountability and reprimand for delivery of substandard care. However to stimulate change in the medical profession requires the development of a standard of care that patients must learn to expect and evaluate through access to information and provision of feedback. This is reportedly the preference of patients particularly in the case of elective procedures, where studies [1] including that of the Dartmouth Center for Informed Choice [6] have shown that patients facing elective procedures—such as elective orthopaedic procedures—benefit greatly from understanding their options, risks, and benefits. In the current evolution toward a patient-centered care model, patients’ personal preferences and values, lifestyles, and family and social circumstances are considered in the decision-making regarding individual options for treatment. This has been identified as one of the important factors constituting high-quality health care [1]. Patients prefer participation in the decision-making process, and when informed often make different choices than patients who are not fully informed [3]. Thus the goal of access to healthcare information is not to oblige patient choice without appropriate support, but rather to involve and educate patients toward exercising a choice that reflects their preferences and values. Regarding the responsibilities of the patient consumer and the healthcare professional, it is overly simplistic to designate public reporting and the practice of quality control as the exclusive responsibility of one or the other. As was alluded to in the text of our article [4], the list of actors certainly includes patients, approximately 55% of whom are younger than 65 years with benefits through employment-based insurance, 30% of whom receive Medicare and Medicaid, and the remainder who represent a segment of the uninsured in the United States [2]. A large segment of these patients would benefit from access to information, and have been active users of existing online vehicles of health information. A 2009 Pew Research study [5] showed that 61% of all US adults sought web-based health information. Approximately 59% of this population were in the 50- to 64-year-old age group, 27% were 65 years old or older, and approximately 44% of this population were in a household annual income bracket of less than $30,000. Furthermore for patients either not capable or not interested in engaging in shared, value-conscious healthcare decisions, the proposed concept of accountability under public reporting would incentivize physicians, health plans, and purchasers to consider this information and guide patients accordingly, as their value-based reimbursement rates become driven by public reports of patient satisfaction. However in addition to patients, the list of stakeholders also includes payers, who will use this information to derive provider payment rates and allocations. It includes purchasers who will consider the information in designing new benefit plans (eg, tiered provider networks, consumer-directed health plans, and global payment models, etc). It also includes healthcare professionals ranging from physicians, nurses, and case managers to hospital administrators and management support staff, who will need this information to perform effective monitoring and evaluation, accurate benchmarking, and continuous quality improvement. Thus, rather than dividing the “professional provider” and the “patient consumer” into two separate groups, this interdependent group of actors requires shared participation of all entities to achieve the intended goals. Finally, regarding the final statement “quality control (being) the responsibility of the medical profession, not of patients”, one could argue that the indication for public reporting and greater patient involvement arose in response to the historical lack of professional oversight in health care. This has been revealed through an extensive body of evidence that highlighted inconsistent and unexplained variations in practice, overuse and underuse of services, insufficient monitoring of safety, outcomes, and the management of healthcare finances and resources. It would be unreasonable to assume that a surge of effective self-regulation will spontaneously arise without an organized shift in the paradigm of healthcare delivery for patients, providers, and purchasers. We believe that public reporting is a necessary building block for value-based health care. Alone, it is not sufficient to provoke the transformational changes we seek to promote in our healthcare system. Bending the cost curve and achieving meaningful quality improvement, we believe, is not obtainable without this critical information.

We appreciate the opportunity to reply to the comments of Drs Wolf, Leithner, and Clar. Their comments regarding our study [1] are centered on the concept of applying risk stratification for patients being treated for an infected THA during the early postoperative period. They state that our study does not account for patient-related risk factors in its analysis and that we overlooked two studies [2, 3] that might have contributed insight into this element of the analysis. As is known, the success or failure of any medical intervention in general, and the treatment of periprosthetic joint infections in particular, are predicated on many factors. The concept of Bayes’ theorem and a priori risk are highlighted in this clinical scenario and are mentioned in our article. We believe strongly that risk stratification has an extremely important role in deciding a treatment regimen. What Wolf et al. fail to mention is that these are just concepts. Even for common orthopaedic procedures such as THA, the elements that lead to meaningful risk stratification are not fully understood or implemented, and moreover, in complex clinical scenarios such as with a periprosthetic joint infection, these elements and their application become even more challenging. The two studies referenced by Wolf et al. [2, 3] serve to highlight the lack of information on this concept in the literature. The study by McPherson et al. [3] reports on a staging system for patients with chronic infection who have had a resection arthroplasty as the first stage of a two-stage procedure. McPherson et al. report that the staging system they used correlated with the ultimate ability to successfully reimplant a prosthesis. Although this study provides insight into the specific clinical scenario of patients with a resection arthroplasty after a chronic infection awaiting a second-stage reimplantation, this does not in apply to the hypothetical clinical scenario of our patient 3 weeks after THA. In addition, although elements of this staging system might be useful for acute postoperative infections, the study by McPherson et al. [3] cannot be applied to fundamentally different clinical scenarios. In the study by DeMan et al. [2], no elements of risk stratification are provided, but rather this is a study reporting on the results of a specific algorithmic approach to infection. In addition and similar to the study by McPherson et al., DeMan et al. do not report on the outcomes of acute postoperative infection, but rather a combination of acute and chronic infections they treated. They also report the use of antibiotic cement for fixation of the femoral and acetabular components in approximately half of their cohort. The use of antibiotic cement for the single-stage approaches is mentioned specifically in our study with reported infection control rates. In addition, we discussed the concept of single- and two-stage exchanges being performed using cementless components. The study by De Man et al. does not apply to the clinical scenario presented by an acute postoperative infection. Although we fundamentally agree with Wolf et al. in their desire to use risk stratification in the analysis of different treatment algorithms, there are no published data that establish these parameters. We agree that prospective studies are warranted to better answer this question.

We thank Dr. Lang for further clarification regarding our article. We are happy to address her concerns. First, regarding the issue of inclusion of the article by Paterson et al. [4], we acknowledged in a response to a previous Letter-to-the-Editor [3], that the existence of “temporary brittle bone disease” as a variant of osteogenesis imperfecta (OI) has been challenged and in some ways shown to be nonscientific. However, all authors of the original paper [2] were unaware of the court ruling from the United Kingdom related to the study by Paterson et al. [4], and we welcome the clarification provided by Dr. Lang. This point is even more relevant in light of the fact that the MOOSE group (Meta-analysis of Observational Studies in Epidemiology) state in their guidelines that because observational studies are vulnerable to bias, confounding, and chance, readers should consider explanations for the observations other than the conclusions of the authors [5]. However, even had we known a priori about the court ruling, the study by Paterson et al. [4] still would have met our search criteria and our inclusion and exclusion criteria. As such, strict observation of systematic review technique would dictate that it be included as the article has not been retracted from its originally published journal. However, we would have made note of the controversy and indicated that his ‘disease’ has been challenged, and that Dr. Paterson has been banished from medical practice. We by no means support the existence of “temporary brittle bone disease” or the work of Dr. Paterson; we simply reported the results of our systematic review. Exclusion of the article would have made our study a selective, not a systematic review because we would have excluded an article that met inclusion and exclusion criteria simply because we did not agree with the authors or their findings. Furthermore, we do not believe that inclusion of the article discredits our entire study. In our article, reference to the work by Paterson et al. [4] regarding temporary brittle bone disease [4] is made only sparingly in the article. Furthermore, of the 914 cases we pooled in our study, the article by Paterson et al. contributed only 39 cases (less than 5%). The omission of their article (based on the facts provided) would not have changed our main conclusion: various bone disorders (primarily OI, rather than temporary brittle bone disease) might be mistaken for child abuse. The main result of our study [2] which would have been affected is the following: “Pooling the studies in which confirmed cases of metaphyseal dysplasia/OI were present, there was an 18.7% (162 of 866) rate of initial misdiagnosis of CAN [child abuse and neglect] or bone disease.” Through exclusion of the article by Paterson et al., that sentence should now read: “Pooling the studies in which confirmed cases of metaphyseal dysplasia/OI were present, there was a 15.7% (130 of 827) rate of initial misdiagnosis of CAN or bone disease.” The purpose our study was simply to note that bone disease (particularly OI) can be mistaken for child abuse and neglect, and should be in the mind of the clinician. The exclusion of the work by Paterson et al. does not change that conclusion. Second, Dr. Lang proposed that we did not correctly cite the data in the 1980 study by Horan and Beighton [1]. The cited article was a review of notes and radiographs of patients with reported bone disease. Dr. Lang stated that we incorrectly presented the information by including 13 children (six in the bone disease category and the remaining seven in the child abuse and neglect category). Dr. Lang believes that the exact data included 15 patients. The actual text of the article reports on 13 cases (representing 15 patients, two of the cases represented two siblings which we treated as a ‘case’). We should have clarified this in our manuscript using the word “cases” as opposed to patients, but our analysis remains the same. On page 246 of the article in Table 1, 13 cases (representing 15 patients) are listed with complete data regarding their initial diagnosis and final diagnosis [1]. From this table, there are six cases in the bone disease category, and seven in the child abuse category. We should have clarified this in our manuscript, but believe that data should still be reported as 13 cases – with our subsequent proportions accurate. Regardless, this once again does not change our conclusion. Finally, Dr. Lang takes issue that we state in our article [2] that: “In many instances, a physician’s own instincts make the diagnosis.” She isolates this statement out of the context of the paragraph. The entire paragraph reads, “The limitations of our study and the literature are not trivial. First, there is no gold standard test for diagnose [sic] CAN; it remains a synthesis of history, physical examination, and radiographic findings. In many instances, a physician’s instincts make the diagnosis. Therefore, any study of CAN is fraught with the danger of misclassification.” This statement is placed in the limitation section of our study as a limitation [2]. This is not our recommendation. We even state in the following sentence that since physicians incorrectly rely on instincts (not a gold standard test), child abuse and neglect are fraught with misclassification. We do not believe, as Dr. Lang states, that the results of our study are inherently incorrect. Our study still reports on 827 cases of metaphyseal dysplasia/OI of which 130 were misdiagnosed as CAN [2]. These data are simply from the systematic review we performed, and we are reporting the results of this review. Exclusion of the 39 cases of Paterson et al. [4] does not inherently change the conclusions of our study as they represent a minimal percentage of our total cases. Furthermore, our use of the patients from the Horan and Beighton [1] study as 13 cases as opposed to 15 patients does not change the results of our study, and represents how the authors reported their data. Our study simply summarizes the literature present regarding bone disease and child abuse and neglect.

We thank Dr. Partridge and his colleagues for their letter. They commented, ”…the distinction between patients with infection and without infection must be questioned as a large proportion of patients deemed to be correctly diagnosed as having aseptic loosening did not have specimens sent for culture.” As we explained [4], before institution of a standard protocol, some patients with aseptic loosening may not have been adequately investigated to rule out periprosthetic joint infection (PJI). The latter explains why intraoperative culture specimens were not sent for some patients. Although their point is valid, it does not detract from the message of the paper. At worst, sending culture specimens for the aseptic cases might have increased the number of “misdiagnosed” aseptic cases adding strength to the message of the article. However, the number of optimal culture specimens is not known. In the recent AAOS Guidelines for Diagnosis of PJI for which a comprehensive literature search was done, Della Valle et al. were not able to address this issue based on evidence [3]. Dr. Partridge and his colleagues also commented, “There is also the likelihood that a proportion of the patients assigned to Group 1 (prosthetic joint infection) on the grounds of definite prosthetic joint infection at the time of subsequent rerevision actually had infection after their revision surgery rather than representing falsely diagnosed aseptic loosening.” We were cognizant regarding the possibility that some of the subsequent infections might have been de novo PJIs and not missed aseptic cases, as we stated in our article. Although plausible, the latter is unlikely as these patients did have abnormal serology, and in some cases synovial cell count, at the time of their index revision. There currently are no definite diagnostic criteria for PJI [1]. We are unaware of any validated criteria specifying the number of culture specimens required to be positive for the case to qualify as PJI, nor is there a definite criterion that specifies the importance of isolation of organisms from broth. Diagnosis of PJI is based on a combination of criteria that may need to be varied on an individual basis. As reported previously, in as much as 7% of PJI cases one is not able to isolate the infecting organism (culture negative cases) [2]. Thus, reliance on isolation of an organism (positive culture) is not accepted as the gold standard for diagnosis of PJI. We disagree with the last comment in the third paragraph that isolation of an organism from a single culture represents contamination. For example, for a patient with abnormal serology and abnormal synovial cell count parameters in whom an organism is isolated from a single culture–even broth, would the latter result not be considered significant? Within the confines of manuscript length, we discussed the details pertinent to transport and processing of culture specimens. We recognize that variations in processing culture specimens might have existed but also acknowledge that this is not unique to this cohort or our institution. We agree that management of patients with PJI requires a team effort. As a center that treats approximately 300 patients with PJI per year, we rely on the expertise of our colleagues from infectious disease, microbiology, pharmacy, rehabilitation, and other disciplines to optimize the care of these patients.

Dr. Beck rightly points out that Figure 1 [3] suggests that a cam-type hip can be diagnosed from an AP radiograph. In the original version of the figure, the CT image in three orthogonal views was included beneath the radiograph, to show that the diagnosis was a three-dimensional one. This original figure is appended (Fig. 1) by way of reassurance that an AP radiograph is not relied on for this diagnosis. Dr. Beck therefore can be assured that cam hips were not misdiagnosed. Fig. 1 Plain radiographs of normal, cam, and pincer-type hips are shown, with CT images of 3d, axial, sagittal and coronal reconstructions below. The green normal hip has alpha and centre-edge angles in the normal range. The red cam hip has a large alpha angle ... If the 3-D method of Beaule et al. [1] is used to describe a cam on the femoral side, I have yet to find a case with an acetabulum that is deeper than normal, thus being able to act as a pincer as described by Ganz et al. [4] in a seminal and widely cited article. Therefore I agree with the conclusion that Dr. Beck draws from the data presented [3]: the acetabulum in pincer hips does appear to be distinctly different from the acetabulum in cam hips. Dr. Beck describes exactly what was observed: there are two separate methods of impingement. However, in a later paper that also is cited widely, Beck et al. stated that the majority of cases are of ‘mixed’ type [2]. Although I agree that most cases have evidence of impingement on the femoral and acetabular sides, I do not agree that the mechanism is ever mixed, and wonder if this important point might have been ‘lost in translation’. I continue to look for the first reported case of coxa profunda with a cam on the femur, or of a cam hip with an acetabulum that is even of average depth. This issue is clinically relevant: the acetabulum of the cam hip is shallow - not deep, therefore “rim trimming” of the acetabular iliac eminence in these hips runs the risk of causing iatrogenic acetabular insufficiency, leading to rapidly progressive hip damage.

We thank Descatha et al. for their interest in our article [3] and their comments. A systematic review and meta-analysis uses a systematic approach to identify evidence from multiple studies to attain an accurate and unbiased estimate of the association between interventions or exposures and events that could be widely applicable to a larger population [4]. By combining patient data from multiple studies appropriately, meta-analyses allow for larger sample sizes and therefore statistical power to determine treatment effects [1, 4]. However, systematic reviews are not without limitations. All reviews are retrospective and observational and therefore are subject to random error and systematic bias [1]. Systematic reviews, when conducted properly, can provide a high level of evidence, improve the precision of the analysis by increasing the sample size, and help to explain differences in study results attributable to heterogeneity [2]. Ultimately, a meta-analysis depends on the quality of the primary studies included in the analysis [2]. We believe that we performed a quality meta-analysis [3], confirmed by high scores on the Oxman and Guyatt index [5], a validated scoring system for the quality of meta-analyses and systematic reviews. Drs. Descatha, Huard, and Duval suggest that by combining studies that used different cross-sectional area cutoffs for positive diagnosis of carpal tunnel syndrome, our results may artificially influence the sensitivity and specificity of the sample. All meta-analyses carry this risk, and our study is no different. We agree that obtaining the raw data from all studies included in the analysis would have yielded more accurate results. However, as obtaining the raw data from every study is not possible, including only studies for which we were able to obtain raw data would introduce substantial selection bias. They also suggested that separate analyses should have been performed at each cross-sectional area cutoff value, however, this would decrease the sample size for each value and add more confusion to an already potentially confusing analysis. We thank Drs. Descatha, Huard, and Duval for observing our failure to include the likelihood ratios in the manuscript and have included a table detailing the ratios (Table 1). Table 1 Studies included in the meta-analysis [3] and reported likelihood positive and negative ratios We respectfully disagree that the specific transducer and ultrasound equipment used in each study is an important factor in the sensitivity and specificity of ultrasound as a diagnostic tool. We found no literature to support the advantage or disadvantage of one transducer over another. We did identify substantial heterogeneity in the criteria used for electrodiagnostic testing and clinical findings in the diagnosis of carpal tunnel syndrome. This heterogeneity, however, mirrors clinical reality where different institutions and physicians use varying criteria. We sincerely thank Descatha et al. for their thoughtful comments and hope we have addressed their concerns.

We thank Drs. Ng and Ellis for their well-taken comments to our article “The Cam-type Deformity of the Proximal Femur Arises in Childhood in Response to Vigorous Sporting Activity” [3]. We agree with their comment that although there is an exponentially increasing number of varied treatment methods in recent years, little is known regarding the etiology of cam-type morphology. In the past, cam-type morphologic features were presumed to arise primarily from a mild or silent capital slip [1, 5]. However, the typical horizontal orientation of the growth plate with extension of the epiphysis onto the neck [4] contradicts this hypothesis in the majority of patients with cam-type impingement. To the best of our knowledge, our study showed for the first time that high-level sports activities (basketball) during childhood and early adolescence might be one important factor determining the final shape of the proximal femur in Caucasians. That means that playing basketball at a high level by this age group represents a risk for the development of a cam-type deformity. Our study however does not provide any confirmation for the hypothesis of Ng and Ellis [2] that high axial loading of the hip is the driving factor in the elite basketball player. Our study simply describes morphologic findings and differences between highly active athletes and a control group during and shortly after the growth period. In contrast to the suspicion of Ng and Ellis that adolescent activities, particularly in flexion-internal rotation, might protect against cam morphologic features, we rather suspect hip activities with vigorous loading during flexion and internal rotation of the hip might be responsible for abnormal growth and an aspherically shaped femur. However it was beyond the scope of our study to define the actual forces and specific damage mechanism leading to cam-type morphology.

To the editor, We read the Level I study by Tarwala and colleagues [11] with great interest. The study compared the operative tourniquet group to cementation tourniquet group in patients undergoing TKA. The authors found no difference in surgical time, postoperative pain, motion of the knee, blood loss, and complications between the two groups. The authors also indicated in their conclusion that they prefer to use the tourniquet only during cementing in TKA. Although the authors mentioned that there were no previous studies comparing the effects of tourniquet used only during cementing, we found two studies on the same topic published before the current study [4, 7]. Kvederas and colleagues [4] compared three groups undergoing TKA in a Level II study. In the first group, the tourniquet was inflated before incision and deflated after hardening of the cement. In the second group, the tourniquet was inflated just prior to cementing and was released after its hardening. In the third group, it was inflated before incision and deflated after closure of the incision. In contrast to Tarwala et al., these authors found higher estimated blood loss with the second group (the group that used the tourniquet only during cementation). The second study by Mittal and colleagues [7] noted higher transfusion rates with the short tourniquet group (cementation tourniquet). The authors had to abandon the study due to unacceptably high transfusion rates in the cementation-only tourniquet group. As both of these studies were not cited by the authors, their findings, which are in contrast to the present study, were not compared in the Discussion section. The authors failed to perform a power analysis at the initiation of the study because similar studies were not available in literature. The timing of deflation of the tourniquet remains unclear in the current study. In the Methods section, it is stated that the tourniquet was released in all patients at the completion of cementation of the patella and the knee held in extension with compression of the patella for the subsequent 10 minutes it took for the cement polymerize. If the tourniquet was released after complete polymerization of the cement, the mean tourniquet time in the cementation tourniquet group of 9 minutes (range = 7 minutes to 14 minutes) is less than the time it took for the cement to polymerize completely. If the tourniquet was released just after implantation, but before complete curing of the cement, blood that would flow after the tourniquet’s deflation would be mixed with cement at the crucial phase of cement polymerization and weaken the interface for cementation. It has been shown that hyperemia following tourniquet deflation peaks at 5 minutes after deflation [5]. Therefore, it would not provide a bloodless bone for cementation, defeating the purpose of using tourniquet only during cementation. Additionally, certain discrepancies were found in the references cited in the text and their actual contribution. In the Introduction, the authors compared randomized controlled trials featuring patients undergoing TKA with or without tourniquet that show no statistical difference in blood loss or less blood loss when no tourniquet is used. The authors provided three additional studies [2, 6, 13] in their References section. However, none of these three papers have studied blood loss with or without tourniquet in TKA. Yang and colleagues [13] investigated the effectiveness and safety of tranexamic acid in reducing postoperative blood loss in TKA, but not of the tourniquet alone. A study by Vandenbussche and colleagues [12] has been quoted as showing no difference or less blood loss without tourniquet. However, the study reports higher blood loss without the use of a tourniquet. Similarly, a study by Kato et al. [3] has been cited as a reference for wound complications following tourniquet use. However, the original study purpose was to detect emboli during the tourniquet inflation phase and to identify the composition of the echogenic material. In the Discussion section, the authors cited two meta-analyses [1, 10] as references for the absence of differences in pain with or without the use of tourniquet. However, both of these articles failed to assess pain as a part of their meta-analysis. Also, no difference in swelling of the knee has been shown as a finding of both these meta-analysis when they have not assessed the same. In fact, both of these studies discussed increased swelling of the extremity with tourniquet use in their Introduction. Alcelik and colleagues used a reference by Silver et al. [8] to cite the increased swelling post-tourniquet use. A study by Tai and colleagues [9] has been mentioned as reference for a study showing that increased drainage has been correlated to tourniquet pressure more than 225-mm of Mercury. However, this study compared the tourniquet and non-tourniquet group with respect to blood loss, soft tissue damage, pain, swelling rehabilitation, and hospital stay. It does not address the correlation between tourniquet pressure and drainage. In fact, Tai et al. [9] did not use a drain in their study in order to avoid excessive blood loss.