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We sought to assess the current literature to present a comprehensive summary of the incidence, common pathogens, and risk factors for infection after anterior cruciate ligament (ACL) reconstruction. PubMed, CINAHL, EMBASE, and Scopus databases were searched for relevant studies reporting on infection after ACL reconstruction. Two reviewers independently screened the extracted studies for adherence to inclusion and exclusion criteria. Studies were selected if they reported on the incidence of infection, pathogens cultured from infected knees, or risk factors for infection after primary ACL reconstruction. Exclusion criteria consisted of studies with fewer than 100 patients or studies that included revision ACL reconstruction. Fifty studies met the inclusion and exclusion criteria, reporting on a total of 316,214 ACL reconstructions. Included studies evaluated between 123 and 104,255 patients. The overall incidence of infection was 0.60% (0.15-2.44%). The most common pathogens were Staphylococcus aureus, S. epidermidis , and coagulase-negative Staphylococci. Five studies reported that the use of hamstring autograft was a statistically significant risk factor for infection after ACL reconstruction, thus making hamstring autograft the most commonly reported risk factor. Other reported risk factors included male sex, use of immuno-suppressive medications or intraarticular steroid injections, prior knee surgery, and diabetes. Systematic review of the literature revealed that infection after ACL reconstruction remains an infrequent event with an incidence of 0.60% (0.15-2.44%). Furthermore, the most common pathogens are from the Staphylococcus genus of bacteria, comprising 84% of all culture-positive infections. Multiple risk factors have been reported for ACL reconstruction; however, statistical significance varied across studies. Together, these findings may help guide physicians in the prevention and treatment of infection after ACL reconstruction., Competing Interests: None declared., (Thieme. All rights reserved.)

The purpose of this study was to evaluate the relationship between the number of all-inside meniscal repair implants placed and the risk of repair failure. We hypothesized that the use of higher numbers of all-inside meniscus repair implants would be associated with increased failure risk. A retrospective chart review identified 351 patients who underwent all-inside meniscus repair between 2006 and 2013 by a sports medicine fellowship-trained orthopaedic surgeon at a single institution. Patient demographics (age, body mass index [BMI], sex) and surgical data (number of implants used, concomitant anterior cruciate ligament reconstruction [cACLR], and tear type/size/location) were recorded. Patients who received repairs in both menisci or who had follow-up < 1-year postoperatively were excluded. Repair failure was identified through chart review or patient interviews defined as a revision surgery on the index knee such as partial meniscectomy, total knee arthroplasty, meniscus transplant, or repeat repair. Logistic regression modeling was utilized to evaluate the relationship between the number of implants used and repair failure. A total of 227 all-inside meniscus repairs were included with a mean follow-up of 5.0 ± 3.0 years following surgery. Repair failure was noted in 68 knees (30.3%)-in 28.1% of knees with fewer than four implants and in 35.8% of knees with four or more implants ( p  = 0.31). No significant increase in failure was observed with increasing number of all-inside medial (odds ratio [OR]: 1.15; 95% confidence interval [CI]: 0.79-1.7; p  = 0.46) or lateral (OR: 0.86; 95% CI: 0.47-1.57; p  = 0.63) implants after controlling for patient age, BMI, cACLR, tear type, or size. Tears of the lateral meniscus located in the red-white and white-white zones had lower odds of failure (OR: 0.14; 95% CI: 0.02-0.88; p  = 0.036) than tears within the red-red zone, and patients with cACLR had lower odds of repair failure (OR: 0.40; 95% CI: 0.18-0.86, p  = 0.024) than those without. The number of all-inside implants placed during meniscus tear repair did not affect the likelihood of repair failure leading to reoperation after controlling for BMI, age, tear type, size, location, and cACLR. LEVEL OF EVIDENCE:  III., Competing Interests: None declared., (Thieme. All rights reserved.)

We hypothesize that larger prior tunnel size is associated with an increased risk of failure of single-stage revision anterior cruciate ligament reconstruction (ACLR) as defined by the performance of a re-revision (third) ACLR on the index knee. Retrospective review identified 244 patients who underwent single-stage revision ACLR at a single center with available preoperative radiographs. Patient and surgical factors were extracted by chart review. The maximum diameter of the tibial tunnel was measured on lateral radiographs and the maximum diameter of the femoral tunnel was measured on anteroposterior radiographs. Record review and follow-up phone calls were used to identify failure of the revision surgery as defined by re-revision ACLR on the index knee. One hundred and seventy-one patients (70%) were reviewed with a mean of 3.9 years follow-up. Overall, 23 patients (13.4%) underwent re-revision surgery. Mean tibial tunnel size was 12.6 ± 2.8 mm (range: 5.7-26.9 mm) and mean femoral tunnel size was 11.7 ± 2.8 mm (range: 6.0-23.0 mm). Re-revision risk increased with tibial tunnel size. Tibial tunnels 11 mm and under had a re-revision risk of 4.2%, while tunnels > 11 mm had a risk of 17.1% (relative risk: 4.1, p  = 0.025). No significant association between femoral tunnel size and re-revision risk was noted. Patients with prior tibial tunnels > 11mm in diameter at revision surgery had significantly increased risk of re-revision ACLR. Further studies are needed to explore the relationship between prior tunnel size and outcomes of revision ACLR., Competing Interests: None declared., (Thieme. All rights reserved.)

We reviewed the literature regarding utility of biologic augmentation in meniscal repair. We hypothesized that the addition of biologic augmentation during meniscal repair improves postoperative knee function and reduces risk of repair failure. PubMed and Embase databases were systematically searched. Included studies were clinical studies in humans, published in English, and reported use of biologic augmentation techniques in addition to meniscal repair (including platelet-rich plasma [PRP], fibrin clot, bone marrow stimulation, meniscal wrapping, and bioscaffolds) for treatment of knee meniscal tears. Outcome measures included repair failure, repeat knee arthroscopic surgery, and magnetic resonance imaging), visual analog scale for pain, the International Knee Documentation Committee questionnaire, the Western Ontario and McMaster Universities Osteoarthritis Index Lysholm's Knee Scoring Scale, and the Knee Injury and Osteoarthritis Outcome Score. Study quality was assessed using the modified Coleman methodology score. Nineteen studies reported repair of 1,092 menisci including six studies that investigated fibrin clot augmentation, five studies that investigated PRP augmentation, three studies that investigated bone marrow stimulation augmentation, two studies that used meniscal wrapping augmentation, and three studies that used other techniques. The level of evidence ranged from I to IV and mean modified Coleman methodology score was 43 (range: 17-69), with higher scores noted in studies completed in recent years. PRP and bone marrow stimulation augmentation appear to decrease risk of failure in patients undergoing isolated meniscal repair but do not improve knee symptom scores. Fibrin clot and trephination augmentation techniques do not have sufficient evidence to support decreased failure risk at this time. Meniscal wrapping augmentation and scaffold implantation augmentation appear to be an attractive option to meniscectomy in complicated tears that are not candidates for repair alone, but further confirmatory studies are needed to support initial data. Evidence supporting augmentation of meniscal repair is limited at this time but suggests that the highest likelihood for effectiveness of augmentation is in the settings of isolated meniscal repair or meniscal repairs that would normally not be amenable to repair., Competing Interests: None declared., (Thieme. All rights reserved.)

We sought to determine whether individual coping strategies and optimism are associated with satisfaction after sports-related knee surgery at the time of rehabilitation completion and whether the association between coping strategies/optimism and satisfaction varies by surgical procedure or length of rehabilitation. A total of 104 recreational and competitive athletes who underwent knee surgery completed preoperative assessments for intrinsic optimism using the revised Life Orientation Test and coping strategies using the brief Coping Orientations to the Problem Experience inventory. Postoperative assessments at completion of rehabilitation (mean: 5.5-month follow-up.; maximum: 15 months) included satisfaction with surgery, return to prior level of sport, and International Knee Documentation Committee (IKDC-S) symptom scores. Eighty-one percent were satisfied after completion of rehabilitation with a 68% return to prior level of sport. Irrespective of surgical procedure or length of rehabilitation ( p  > 0.25, all comparisons), greater reliance on others for emotional support as a coping mechanism increased risk of dissatisfaction after surgery (per point: odds ratio [OR]: 1.75; confidence interval [CI]: 1.13-2.92; p  = 0.01), whereas greater use of positive reframing as a coping mechanism was protective (per point: OR: 0.43; CI: 0.21-0.82; p  = 0.009). Intrinsic optimism was not predictive of postoperative satisfaction ( p  = 0.71). Satisfied patients had mean 13.5 points higher IKDC-S scores at follow-up than unsatisfied patients ( p  = 0.001). Patients who returned to prior level of sport had significantly higher satisfaction scores than patients who had not. Irrespective of surgical procedure or length of rehabilitation, use of positive reframing and reliance on others for emotional support are positive and negative predictors, respectively, of satisfaction after sports-related knee surgery. Preoperative optimism is not predictive of postoperative satisfaction., Competing Interests: D. C. F. reports personal fees from Depuy Mitek, Smith & Nephew, Vericel, Ceterix Orthopaedics, Conmed, Histogenics Corp., Moximed Inc., and Zimmer Biomet, outside the submitted work. D. C. F. is a consultant for Smith & Nephew, DePuy Mitek, and Zimmer., (Thieme. All rights reserved.)

We sought to evaluate the effectiveness of autologous chondrocyte implantation (ACI) for the treatment of adult osteochondritis dissecans (OCD) lesions according to patient-reported outcomes, complication rates, and failure rates. A search of MEDLINE, Scopus, and Cochrane Library was performed to identify clinical studies (levels I-IV) reporting outcomes after ACI treatment for OCD in adult knees. Our inclusion criteria included the following: (1) published between January 2000 and April 2017, (2) stable and unstable OCD lesions of the knee, (3) use of ACI in at least one group, (4) subjects ≥18 years old or skeletally mature, (5) inclusion of at least one patient-reported clinical outcome measure, and (6) written in English. A total of nine studies (179 patients), mean age of 27.6 years (range: 18-49 years), were included. There were 227 OCD lesions with an average size of 4.1 cm 2 (range: 1.2-9.4 cm 2 ). The average follow-up was 61.3 months (range: 6.5-120 months). In general, there was significant improvement in symptoms, but better results occurred among active male patients with smaller lesions as well as younger patients. Statistically significant improvement in patient-reported outcomes was reported in all studies. There were 23 complications reported (15.6%), including 12 failures (8.2%). Significant improvement in clinical outcome measures demonstrates clinical efficacy of autologous cartilage therapies for the treatment of OCD in adult patients. Better outcomes are often observed with males, active patients, smaller lesion sizes, and younger age at the time of surgery., Competing Interests: None declared., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Femoral nerve block (FNB) has been proposed for pain control following anterior cruciate ligament (ACL) reconstruction. Although numerous studies have assessed the efficacy of FNBs, there has been little to no research into the effect of such blocks on postoperative strength and patient-reported outcomes. We hypothesized that performance of an FNB would result in decreased quadriceps strength and poorer patient-reported outcome scores within the first 6 months following ACL reconstruction. A total of 30 patients scheduled to undergo hamstring autograft ACL reconstruction following an acute ACL injury were randomized to a single-shot FNB group or a control group. Preoperatively, patients completed a Knee Injury and Osteoarthritis Outcome Score (KOOS) and isokinetic quadriceps strength testing at 60 degrees/second. At 6 weeks postoperative, 29 of 30 patients completed a KOOS and isometric quadriceps strength testing at 90 degrees. At 6 months postoperative, 23 of 30 patients completed a KOOS and isokinetic strength testing. Quadriceps femoris strength limb symmetry indices (QF-LSI) were calculated at all time points. Repeated measures analysis of variance (ANOVA) models were then utilized to model the effect of FNB and time on QF-LSI as well as KOOS subscales for activities of daily living, pain, and symptoms. QF-LSI and all KOOS subscales demonstrated improvement with time following ACL reconstruction. Repeated measures ANOVA demonstrated that patients who underwent FNB had a mean QF-LSI that was 13.4% lower than the control group ( p  = 0.005) and poorer KOOS symptoms subscale scores (10.4 point difference, p  = 0.032) at 6 weeks postoperative compared with controls. At 6 months postoperative, no differences were noted in QF-LSI or any of the KOOS subscales based on block status. FNB resulted in decreased strength and poorer KOOS symptom subscale score at 6 weeks following ACL reconstruction compared with controls. These differences resolved by 6 months postoperative. The long-term effect of delayed quadriceps recovery on movement patterns and functional outcome remains unknown and requires further study. The study is a randomized controlled trial with level of evidence 1., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

It is unknown whether body mass index (BMI) influences outcomes of meniscus repair. We hypothesized that increased BMI would be associated with increased risk of failure. A retrospective study was performed involving patients who had undergone meniscus repair between 2008 and 2012. Chart review and phone interviews were conducted to determine which patients required additional surgery. Patients were categorized as normal BMI (<25) or increased BMI (≥25). Of the 305 patients who met study criteria, 216 (70.8%) were available for follow-up at a mean of 19 months postoperatively. A total of 100 patients (46.3%) had a BMI <25 and 116 (53.7%) patients had a BMI ≥25. BMI was less than 35 in 90% of patients. Thirty-four patients (15.7%) required further surgery for a repair failure. Failure occurred in 20 patients (20%) in the normal BMI group and 14 patients (12%) in the increased BMI group ( p  = 0.14). Logistic regression revealed a trend toward decreased odds of repair failure in the increased BMI group (odds ratio: 0.46; 95% confidence interval: 0.20-1.05; p  = 0.065). Patients with a BMI ≥25 did not have a higher risk of meniscus repair failure relative to those with a BMI <25. Given these findings, surgeons should not consider moderately increased BMI as a contraindication to meniscal repair. The effect of BMI greater than 35 on outcomes of meniscal repair remains unclear and warrants further study., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Competing Interests: Disclosure The authors report no conflicts of interest in this work.

The purpose of this study was to systematically review the literature relative to the following question: Is preoperative magnetic resonance imaging (MRI) an accurate instrument for the assessment of the size of knee articular cartilage defects compared with arthroscopy? A systematic search was performed in September 2011 using PubMed MEDLINE (from 1966), CINAHL (from 1982), SPORTDiscus (from 1985), SCOPUS (from 1996), and EMBASE (from 1974) databases. Four studies (one study of Level II and three studies of Level III) were identified that met the predetermined inclusion and exclusion criteria. The ability of MRI to preoperatively assess the size of cartilage lesions was highly variable. As a result of inconsistencies between imaging techniques, the methodological variability and shortcomings of the studies, and the limited amount of data available, a meta-analysis was not performed. There is some evidence that MRI is an accurate tool for preoperatively assessing the dimensions of articular cartilage defects. However, because of the heterogeneity of MRI sequences and the paucity of literature related to preoperative sizing, it is not possible to make definitive conclusions regarding the global clinical utility of MRI for guiding the selection of therapeutic strategies., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

We present a case of a 24-year-old, otherwise healthy, man who sustained a right knee injury after a fall. A small, comminuted inferior pole patella fracture with medial and lateral retinacular tears was encountered that required a small, nonarticular partial patellectomy and patellar tendon repair. An uneventful postoperative course was complicated by a fall onto a flexed knee and rerupture of the patellar tendon at 3 months following surgery. Intraoperatively, a significant tissue void was seen in the area of the prior repair. The patellar tendon was reconstructed with semitendinosus and gracilis autograft. At 1 year follow-up, the patient had regained a normal gait, had no pain, and had full range-of-motion without extensor lag., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Autologous chondrocyte implantation (ACI) is an effective method of treatment of chondral defects of the knee. ACI outcomes are influenced by patient-, knee-, and lesion-specific factors. We compiled subject-level data from current studies on ACI and quantitatively analyzed this data set for associations between patient-, knee-, and lesion-specific factors and the outcome of ACI surgery. A systematic review of studies investigating ACI treatment outcomes in the knee was performed. Only studies that published subject-level data were included. Data on patient and lesion characteristics, as well as clinical outcome scores, were collected. Thirteen studies (305 defects) were included in this review. These studies showed that ACI treatment improves clinical outcomes in different patient populations. However, subject-specific variables such as patient age, gender, body mass index, duration of preoperative symptoms, as well as defect size and location were not associated with International Knee Documentation Committee score or visual analog scale score changes (p > 0.05 for all). Covariate analysis showed that patient age was related to symptom duration prior to surgery (p = 0.009). ACI surgery has been shown to improve outcomes in patients with chondral lesions of the knee. Despite evidence in the literature showing that multiple patient-, knee-, and lesion-specific factors may influence treatment outcomes, our review shows that these factors, solely, do not affect outcomes. However, together, they may synergistically affect outcomes., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

We used bovine tibiae and two-stranded human anterior tibialis tendon grafts to compare biomechanical properties of two tibial fixation devices, the Milagro Interference Screw (Milagro) and the Bio-Intrafix Soft Tissue Tibial Fixation System (Bio-Intrafix). A total of 24 constructs (12 with each type of fixation) underwent biomechanical testing with 12 matched constructs undergoing uniaxial loading to failure (rate of 1 mm/sec) and the other 12 matched constructs undergoing cyclic loading (10,000 cycles at 1 Hz with a loading range of 125 to 375 N). All constructs failed by slippage of one or both ends of the anterior tibialis graft past the fixation device. One of the six Bio-Intrafix specimens failed before 10,000 cycles; four of the six Milagro specimens failed before 10,000 cycles. Bio-Intrafix, which is designed for a four-stranded graft, provided superior fixation to a traditional bioabsorbable interference screw in a two-stranded soft tissue graft at one of the weakest links in anterior cruciate ligament reconstruction surgery., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

We evaluated two newer forms of femoral fixation of hamstring grafts for anterior cruciate ligament reconstruction, the Endobutton direct (Smith and Nephew, Andover, MA) and Femoral intrafix (Depuy Mitek, Raynham, MA), and compare them to devices that have been evaluated in the literature, the AXL Crosspin (Biomet, Warsaw, IN) and Biotransfix II (Arthrex, Naples, FL). Paired hamstring tendon allografts were fixed in the femoral tunnel of 24 cadaveric bovine knees (6 per group) according to each device's specifications. The free ends (tibial sides) were fixed to the materials testing machine via custom-made cryo-clamps. In Phase I, single load to failure and stiffness were evaluated, and in Phase II, peak displacement was evaluated while cyclic loading was performed over 1000 cycles. One-way analyses of variance were performed to test for differences between groups. There were no significant differences in failure load (p = 0.42) or stiffness (p = 0.39) between the fixation devices. There was also no significant difference in peak displacement measured during the cyclic loading phase (p = 0.32). Our findings suggest that the newer generation devices, Endobutton direct and Femoral intrafix, have similar strength in single load to failure and similar peak displacement during cyclic loading as compared with clinically proven Crosspin techniques. These newer devices, which are designed to accommodate for more anatomic femoral tunnel placement, may provide a reasonable alternative without compromising biomechanical properties.

This study aimed to determine the incidence of meniscal tears and describe the tear morphology and selected treatment in patients undergoing anterior cruciate ligament (ACL) reconstruction. We also will discuss the potential market for future tissue engineering aimed at preserving meniscal function. A multicenter cohort of 1014 patients undergoing ACL reconstruction between January 2002 and December 2003 was evaluated. Data on patient demographics, presence of a meniscus tear at time of ACL reconstruction, tear morphology, and meniscal treatment were collected prospectively. Meniscal tears were categorized into 3 potential tissue engineering treatment strategies: all-biologic repair, advanced repair, and scaffold replacement. Of the knees, 36% had medial meniscal tears and 44% had lateral meniscal tears. Longitudinal tears were the most common tear morphology. The most frequent treatment method was partial meniscectomy. Thirty percent of medial meniscal tears and 10% of lateral meniscal tears are eligible for all-biologic repair; 35% of medial meniscal tears and 35% of lateral meniscal tears are eligible for an advanced repair technique; and 35% of medial meniscal tears and 55% of lateral meniscal tears are eligible for scaffold replacement. Although meniscal preservation is generally accepted in the treatment of meniscal tears, most tears in this cohort were not repairable, despite contemporary methods. The results of this cohort will hopefully stimulate and focus future research and development of new tissue engineering strategies for meniscus repair.