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Abstract Purpose One of the most common types of coronal plane alignment of the knee (CPAK) is type I, which is characterised by varus alignment and apex distal joint line obliquity. The purpose of this study was to evaluate the association of changes in arithmetic hip–knee–ankle angle (aHKA) with both postoperative joint laxity and patient‐reported outcome measures (PROMs) in patients with CPAK type I following mechanical alignment (MA) total knee arthroplasty (TKA). Methods Of 111 consecutive knees in 92 patients with osteoarthritis who underwent primary TKA, 80 knees (72.0%) with CPAK type I phenotype preoperatively were evaluated. All TKAs were performed to achieve neutral MA by a medial stabilising gap balancing technique. Pre‐ to postoperative change in aHKA was defined as ΔaHKA. The 80 CPAK type I knees were divided into a larger ΔaHKA group (>7°) and a smaller ΔaHKA group (≤7°). PROMs, including the Knee Society Score and Forgotten Joint Score‐12, were assessed before and 2 years after surgery. Pre‐ and postoperative joint laxity was assessed using a Telos arthrometer. Results Twenty‐two knees showed a larger ΔaHKA, and postoperative lateral joint laxity in varus stress was significantly greater in these patients than in those with a smaller ΔaHKA (6.8° vs. 4.5°, p = 0.006). There were no significant differences between the groups in PROMs (p = n.s.). Conclusions Postoperative lateral laxity was associated with larger aHKA changes than smaller aHKA changes in CPAK type I knees after TKA. However, no statistically significant differences in PROMs were found according to the amount of change in aHKA. Level of Evidence Level III.

Purpose: Outcomes after combination of anterior cruciate ligament (ACL) reconstruction (ACLR) with unicompartmental knee arthroplasty (UKA) or high tibial osteotomy (HTO) have been widely reported, but previous systematic reviews have included articles published before 2000 and do not necessarily reflect recent trends. We conducted a thorough investigation to address (1): What are the recent surgical trends in simultaneous ACLR and UKA or HTO? and (2) What are the issues in these surgeries? based on a comprehensive systematic analysis. Methods: A systematic surveillance was performed in accordance with the PRISMA guideline. The inclusion criteria were as follows: simultaneous ACLR and UKA or HTO for medial osteoarthritis (OA) with ACL deficiency; clinical outcomes and complications recorded; publication date after 2000.A total of 1466 potentially relevant articles were identified; after exclusions, 31 articles that included 744 knees were analyzed. Fourteen articles included 330 knees underwent simultaneous ACLR and UKA (UKA group) and 17 articles included 414 knees underwent simultaneous ACLR and HTO (HTO group). Results: Overall, complications were found in 14 knees (4.2%) in the UKA group and 47 knees (11.3%) in the HTO group. Re-rupture of the ACL was observed in only the HTO group (6 knees: 1.4%). Revision to TKA occurred in 8 knees (2.4%) in the UKA group and 1 knee (0.2%) in the HTO group. No standardized outcome measures for clinical assessment were used for all studies. Conclusion: The systematic surveillance of studies published since 2000 on the outcomes and complications of simultaneous ACLR and UKA or HTO for medial OA with ACL deficiency indicates an increasing number of reports on simultaneous ACLR and HTO or UKA in recent years. Favorable clinical results were achieved in both treatment groups.

Aims: Orthopaedic surgery requires grafts with sufficient mechanical strength. For this purpose, decellularized tissue is an available option that lacks the complications of autologous tissue. However, it is not widely used in orthopaedic surgeries. This study investigated clinical trials of the use of decellularized tissue grafts in orthopaedic surgery. Methods: Using the ClinicalTrials.gov (CTG) and the International Clinical Trials Registry Platform (ICTRP) databases, we comprehensively surveyed clinical trials of decellularized tissue use in orthopaedic surgeries registered before 1 September 2022. We evaluated the clinical results, tissue processing methods, and commercial availability of the identified products using academic literature databases and manufacturers’ websites. Results: We initially identified 4,402 clinical trials, 27 of which were eligible for inclusion and analysis, including nine shoulder surgery trials, eight knee surgery trials, two ankle surgery trials, two hand surgery trials, and six peripheral nerve graft trials. Nine of the trials were completed. We identified only one product that will be commercially available for use in knee surgery with significant mechanical load resistance. Peracetic acid and gamma irradiation were frequently used for sterilization. Conclusion: Despite the demand for decellularized tissue, few decellularized tissue products are currently commercially available, particularly for the knee joint. To be viable in orthopaedic surgery, decellularized tissue must exhibit biocompatibility and mechanical strength, and these requirements are challenging for the clinical application of decellularized tissue. However, the variety of available decellularized products has recently increased. Therefore, decellularized grafts may become a promising option in orthopaedic surgery. Cite this article: Bone Joint Res 2023;12(3):179–188.

Abstract Introduction This study evaluated the validity of the AP3 × ML3 reduction quality classification, which applies the concept of positive medial cortical support. Methods A total of 120 trochanteric fractures classified as AO Foundation/Orthopedic Trauma Association 31A1 and A2 were retrospectively analyzed. The validity of the AP3 × ML3 classification was evaluated by comparison with the Baumgaertner reduction quality criteria. When using the AP3 × ML3 classification, reduction quality was divided into three classes based on the degree of anterior cortical contact between the proximal and distal fragments. Reduction quality was also divided into three classes when using the Baumgaertner criteria. The frequency of mechanical complications, including cut­out, delayed union, and excessive migration of the lag screw, was retrospectively assessed. Intra-observer and inter-observer reliability was assessed using the intraclass correlation coefficient (ICC). Results Mechanical complications included 4 cases of cutout (3.3%) and 1 of delayed union (0.8%). Mechanical complications occurred for all levels of reduction quality in both classifications, except for the acceptable of the Baumgaertner criteria. When reduction quality was rated as good, acceptable, and poor the incidence of mechanical complications was 2.5%, 5.7%, and 16%, respectively, under the AP3 × ML3 classification and 3.3%, 0%, and 15.0%, respectively, under the Baumgaertner criteria. The ICC was 0.80 for intra-observer reliability and 0.57 for inter-observer reliability when using the AP3 × ML3 classification and 0.85 and 0.34, respectively, when using the Baumgaertner criteria. Conclusion The AP3 × ML3 classification was reliable and easy to use compared with the widely used Baumgaertner reduction quality criteria. Level of evidence 4

Abstract Background Change in the joint line convergence angle (JLCA) of the knee after high tibial osteotomy (HTO) is difficult to predict accurately. Given that any change in JLCA is intra-articular, the shape of the articular surface, including the bone morphology of the proximal tibia, may affect the alignment of the knee joint postoperatively. The purpose of this study was to investigate the relationship between the shape of the tibial plateau and postoperative alignment of the knee joint by focusing on changes in JLCA. Methods One hundred and nine knees that underwent HTO were retrospectively reviewed. The shape of the tibial plateau was classified based on the slope of the medial and lateral articular surfaces as depressed, flat (within 3 degrees), or convex (pagoda-like). The relationship between the shape of the tibial plateau and radiological parameters was investigated. Results The shape of the tibial plateau was depressed in 38 knees, flat in 52 knees, and pagoda-like in 19 knees. There was a moderate correlation between the postoperative change in JLCA and the preoperative hip-knee-ankle angle for knees with a pagoda-shaped tibial plateau (r = 0.56) but not for the other two shapes. Conclusions These findings suggest that knees with marked varus deformity before HTO are likely to show more change in JLCA postoperatively if the tibial plateau is pagoda-shaped than if it has a depressed or flat shape. The advantage of focusing on the bone morphology of the proximal tibia is that surgeons can easily perform visual assessment using preoperative radiograph.

Abstract Background Although favorable long-term survival of Oxford unicompartmental knee arthroplasty (UKA) has been reported regardless of postoperative varus alignment, the effect of degree of varus alignment on patient-reported outcome measures (PROMs) remains unclear. Furthermore, the Forgotten Joint Score-12 (FJS-12), which has a low ceiling effect, may be useful for such assessment. The objective of this study was to evaluate short-term clinical outcomes after Oxford UKA in knees with a greater degree of preoperative varus alignment focusing on use of the FJS-12. Methods This retrospective study involved 66 knees that had undergone primary Oxford UKA. Based on the hip-knee-ankle angle, the knees were divided into two alignment groups: severe varus group (≥ 185° varus alignment) and a mild varus group (

Abstract Background Knee replacement is a very effective and indispensable treatment option for end-stage knee arthritis, and the number of cases has been increasing worldwide. A replaced knee joint without patient joint awareness is thought to be the ultimate goal of artificial knees. Joint awareness reportedly correlates with patient satisfaction. Although numbness around a replaced knee is a minor but common problem, its effect on postoperative outcome is controversial. Joint awareness also is sensitive to subtle abnormalities of the joint, so it must be negatively affected by numbness. Although numbness is minor, it cannot be ignored to further improve knee replacement outcomes. This study investigated the relationship between patient-reported numbness and other patient-reported outcome measures (PROMs), including joint awareness, and kneeling. We developed a numbness score based on a 5-point Likert scale on frequency of numbness, with an intraclass correlation coefficient of 0.76 and higher scores indicating less numbness. Methods The numbness score, New Knee Society Score (KSS), Knee Injury and Osteoarthritis Outcome Score (KOOS), Forgotten Joint Score-12 (FJS-12), and other clinical and radiological data from 311 patients (394 primary knee replacements) were analyzed. Kneeling ability was evaluated by using kneeling-specific items in the KSS (KSS-Kneeling). Results No numbness was found in 170 knees (43.1%), and some degree of numbness was found in the remaining 224 knees (56.9%). The numbness score showed weak-to-moderate correlations with KSS-Symptoms (r = 0.44), KSS-Satisfaction (r = 0.41), KSS-Activities (r = 0.29), and all KOOS subscales (r = 0.23–0.44), and FJS-12 (r = 0.42). Multiple regression analyses suggested that midline incision positively affected the numbness score over the anteromedial incision (p = 0.04) and that a better numbness score (p = 0.001), male sex (p

Abstract Purpose The effect of open‐wedge high tibial osteotomy (OWHTO) on the preoperative neutral alignment of the knee is unknown. The purpose of this study was to clarify the clinical outcome of OWHTO with neutral alignment, defined as within 4 degrees of varus. Methods This retrospective study included 72 knees with varus that underwent medial OWHTO. The knees were divided according to the preoperative hip‐knee‐ankle angle into a neutral alignment group (≤ 4° of varus alignment) and a varus alignment group (> 4° of varus alignment). The Knee Injury and Osteoarthritis Outcome Score (KOOS) and the Forgotten Joint Score‐12 (FJS‐12) were evaluated preoperatively and during at least 2 years of follow‐up postoperatively. Results There were no significant differences between the preoperative FJS‐12 (17.9 versus 23.7; p = 0.16) and postoperative FJS‐12 (57.3 versus 60.6; p = 0.52) or KOOS subscale scores (p > 0.05) in the neutral alignment group or the varus alignment group. Each group had a mean change in the KOOS subscale scores that exceeded the minimum clinically important difference. Conclusion The short‐term clinical results of OWHTO for neutral alignment were as favourable as those for varus malalignment. Level of evidence IV.

Abstract Purpose Prolongation of operation time due to registration and pin insertion has been reported with robotic‐assisted total knee arthroplasty (RATKA), and there has been concern about an increase in the postoperative incidence of deep vein thrombosis (DVT). In this study, we compared the incidence of DVT after RATKA with that after conventional manual TKA (mTKA). Methods This consecutive retrospective series included 141 knees that underwent primary TKA using the Journey II system. The CORI robot was used. There were 60 RATKAs and 81 mTKAs. Doppler ultrasound was performed in all patients on postoperative day 7 to determine whether DVT was present. Results The operation time was longer in the RATKA cohort (99.5 min vs 78.0 min, p

Abstract Background Patellofemoral overstuffing after total knee arthroplasty (TKA) can cause limited range of motion and anterior knee pain. This study compared anterior prominence of femoral components among different prothesis designs in surgical simulation models utilizing the anterior reference (AR) and posterior reference (PR) techniques. Methods Surgical simulations were performed using on a three-dimensional planning system preoperative computed tomography data of consecutive 30 patients with knee osteoarthritis scheduled to undergo TKA. Four implant models were used: Attune, Persona, Journey II, and Legion. Rotational alignment was set parallel to the transepicondylar axis and size was selected based on the absence of notch formation in the femoral anterior cortex and the best fit with the shape of the medial posterior femoral condyle. For each combination of surgical technique (AR or PR method) and implant model, measurements were taken of the maximum medial, central, and lateral prominence of the implant from the anterior femoral cortex. Results Using either the AR or PR method, the medial and central prominences were significantly lower with Journey II than with the other models. The lateral prominence was the lowest with Attune in the AR method. The AR method was associated with significantly less prominence compared with the PR method, regardless of implant model. Conclusions The degree of anterior prominence of the femoral implant is affected by the implant design when the AR method is used. The PR method is associated with greater anterior prominence compared with the AR method, and the pitch size is an additional factor in the PR method. Surgeons should be familiar with implant designs, including the thickness of the anterior flange and the available size selections.

Abstract Background The incidence and characteristics of deep vein thrombosis (DVT) following total knee arthroplasty (TKA) without pharmacologic prophylaxis have not been fully investigated. This study aimed to determine whether there are any differences in the incidence, location, and characteristics of DVT following TKA with pharmacologic prophylaxis and without pharmacologic prophylaxis. Methods A total of 156 knees were retrospectively evaluated for DVT following TKA by duplex ultrasound on postoperative day 7, after excluding 60 knees from 216 consecutive knees because of antiplatelet or anticoagulant use before surgery, history of venous thromboembolism, or bleeding risk. The 156 knees included in the analysis were divided into two groups: with pharmacologic prophylaxis (n = 79) and without pharmacologic prophylaxis (n = 77). Results The overall incidence of DVT was 34% (54/156 knees). DVT was detected in 31.6% of knees with pharmacologic prophylaxis and in 37.6% of knees without pharmacologic prophylaxis; the difference was not statistically significant. Soleal vein thrombus was observed in 74.6% of the knees with DVT and non-floating thrombus was observed in 98.7%. There were no obvious between-group differences in thrombus characteristics such as compressibility, echogenicity, mean vein diameter, and whether the thrombus was attached to the vein wall or free-floating. Conclusions No differences were found in the incidence, location, or characteristics of DVT following TKA with or without pharmacological prophylaxis.

Abstract Background The neurovascular bundle containing the deep peroneal nerve has a potential risk of injury during open-wedge high tibial osteotomy (OWHTO), particularly due to drilling for bicortical fixation at distal screw holes. Therefore, monocortical fixation is recommended for distal fixation of a long locking plate as long as good stability is ensured. The purpose of this study was to analyse the biomechanical properties of monocortical fixation of distal locking screws for OWHTO. Methods Three-dimensional models of bone and fixation materials simulating OWHTO were created using computed tomographic data of patients and material data of a T-shaped long locking plate and screws. Three of the four distal screws of the locking plate were chosen for a bicortical fixation or monocortical fixation procedure. In addition, loss of correction was assessed by measuring the medial proximal tibial angle (MPTA) in patients who underwent OWHTO with two bicortical and two monocortical distal fixation screws at 1 month and 1 year after surgery. Results No significant differences in stress were observed in either the normal or osteoporotic bone model between the monocortical and bicortical fixation models, including in the area of the lateral hinge at the osteotomy site. Furthermore, there were no significant differences in MPTA between the early post-operative period and 1-year follow-up. Conclusions The monocortical fixation method for three distal screws of the locking plate did not worsen the mechanical properties of fixation for OWHTO using a long locking plate with four proximal and four distal screws. In actual surgery, the number of distal bicortical screws should be reduced based on the patient’s condition, taking into account the risk of lateral hinge fracture and unexpected surgical complications. Using at least two bicortical screws would be practical considering the various factors related to reduced fixing ability.

Abstract We report a case of tibial shaft fracture after open‐wedge distal tibial tuberosity osteotomy (OWDTO). The use of a lag screw for a lateral hinge fracture in OWDTO requires careful postoperative rehabilitation and follow‐up. We discuss concerns related to the mechanical strength at the osteotomy site after OWDTO to prevent fracture.

Abstract Purpose To describe the indications for, and surgical technique of, tibial condylar valgus osteotomy (TCVO). Indications TCVO is commonly performed in patients with middle-to-end-stage medial unicompartmental osteoarthritis. Among the most important TCVO indication criteria are the types of tibial plateau shape. The convex-type (also called “pagoda-type”), with over a 5° joint line convergence angle on the standing X-ray, meets the indication criteria for TCVO. Surgical technique An L-shaped osteotomy is performed from the medial side of the proximal tibia to the lateral beak of the intercondylar eminence. The apex of the L-shaped osteotomy line is on the medial border of the patellar tendon insertion. Surgeons should note the direction of the chisel (during the osteotomy) to the intercondylar eminence following fluoroscopic guidance. The posterior cortical bone is cut under a lateral view observation, and the crossed-leg position is adopted to prevent injury to the popliteal blood vessels. The spreader should be positioned at the posterior cortical bone to avoid increasing the tibial slope. The locking plate reliably stabilizes the osteotomy and helps shorten the period of postoperative rehabilitation. Conclusions TCVO adjusts varus deformity alongside joint congruity. Accurate identification of indications and a detailed surgical plan would ensure effective correction and proper alignment. Additional osteotomies are recommended in case of under-correction of the varus limb deformity. TCVO is an effective intervention in patients with advanced knee osteoarthritis and lateral joint laxity with the pagoda-type tibial plateau shape.

Abstract Background Some patients complain of noise after total knee arthroplasty (TKA). Controversy still exists on how the noise affects the clinical outcomes, including joint awareness, after TKA. The Forgotten Joint Score—12 (FJS-12) measures the clinical outcomes focusing on joint awareness after surgery. The Knee Society Scoring System—2011 (KSS-2011) includes questionnaires for satisfaction, expectation, and functional activities. The aim of this study is to clarify the relationship among FJS-12, KSS-2011, and the noise. Furthermore, the relationship between FJS-12 and KSS-2011 was validated. Methods Using FJS-12 and KSS-2011, 295 knees from 225 patients who underwent TKA were retrospectively evaluated. Noise perception was evaluated by a questionnaire with five grades, a method that follows the questionnaire form of FJS-12 (“Are you aware of the noise of your artificial joint?”; never, almost never, seldom, sometimes, mostly). Correlations among FJS-12, KSS-2011, and noise were analyzed. The patients were divided into four groups based on the mechanism of their implant [cruciate retaining, posterior stabilized, cruciate sacrificed, and bicruciate stabilized (BCS)]. FJS-12, KSS-2011, and noise were compared among the groups. Results A strong correlation was found between FJS-12 and total score of KSS-2011 (0.70; P

Abstract Purpose Favorable clinical results have been reported following high tibial osteotomy (HTO) for medial meniscus posterior root tear (MMPRT) in knees with varus alignment. However, the effect on the preoperative neutral alignment of the knee is not known. This study sought to evaluate the clinical outcomes of medial open‐wedge HTO for MMPRT with neutral alignment. Methods We retrospectively reviewed 119 medial open‐wedge HTOs and analyzed 22 knees with MMPRT. The knees were divided according to the preoperative hip‐knee‐ankle angle into a moderate varus alignment group (≤4° of varus alignment) and a varus alignment group (> 4° of varus alignment). The Knee Injury and Osteoarthritis Outcome Score (KOOS) and Forgotten Joint Score‐12 (FJS‐12) values were evaluated preoperatively and at the latest follow‐up. The healing status of MMPRT at the time of second‐look arthroscopy, performed at a mean of 15.4 ± 4.2 months, was compared with that after the primary HTO. Results There were 11 knees in the moderate varus alignment group and 11 in the varus alignment group. In terms of perioperative patient‐reported outcome measures, there was no significant difference in the preoperative or postoperative KOOS subscale score or FJS‐12 score between the moderate varus and varus alignment groups. The healing rate was significantly higher in the moderate varus alignment group. Conclusion Favorable clinical results were obtained by medial open‐wedge HTO in knees with MMPRT and moderate varus alignment in the short term. Surgeons should consider the indications for medial open‐wedge HTO, even with moderate varus alignment, when planning treatment for MMPRT with persistent knee pain. Level of evidence IV

Abstract This report presents a case of deep peroneal nerve palsy caused by an injury during drilling for distal locking screws of a T‐shaped locking plate used for osteosynthesis of medial open‐wedge high tibial osteotomy. A cadaveric simulation study reproduced the risk of injury during the surgery.

Dislocation of the hip joint in adults is usually caused by high-energy trauma such as road traffic accidents or falls from heights. Posterior dislocation is observed in most cases. However, atraumatic anterior dislocation of the hip joint is extremely rare. We present a case of atraumatic anterior dislocation of the hip joint that was induced by an activity of daily living. The possible causes of this dislocation were anterior capsule insufficiency due to developmental dysplasia of the hip, posterior pelvic tilt following thoracolumbar kyphosis due to vertebral fracture, and acetabular anterior coverage changes by postural factor. Acetabular anterior coverage changes in the sagittal plane were measured using a tomosynthesis imaging system. This system was useful for elucidation of the dislocation mechanism in the present case.