Mikiko Handa

Purpose: This study aimed to clarify lower limb alignment characteristics and the relationship between coronal and sagittal lower limb alignment in Japanese patients with knee complaints but without knee osteoarthritis (KOA).Methods: This retrospective study included 200 knees from Japanese patients with knee complaints but without KOA aged 60 years and under presenting with knee complaints between May 2020 and May 2023. We assessed coronal parameters, including mechanical hip knee angle (mHKA), arithmetic HKA (aHKA) mechanical lateral distal femoral angle and medial proximal tibial angle (MPTA), and sagittal parameters, such as medial posterior tibial slope (MPTS) and lateral posterior tibial slope (LPTS). In addition, we compared differences between CPAK types.Results: A weak positive correlation was found between mHKA and MPTS, but not with aHKA. Moderate negative and moderate positive correlations were found between mHKA and MPTA and between medial and LPTS, respectively.Conclusions: Little correlation was found between the coronal and sagittal parameters in patients with knee complaints but without KOA.Level of Evidence: Level Ⅲ.

Purpose: Medial meniscus posterior root tears (MMPRT) are a risk factor for knee osteoarthritis. The predominant treatment for MMPRT is transtibial pullout repair, and loop suture remains the gold standard procedure. This study aimed to investigate the structural properties of the meniscus‐suture‐tibia (MST) complex after loop stitch using ultra‐high molecular weight polyethylene (UHMWPE) suture tape of different thicknesses.Methods: This study used 20 fresh porcine MMPRT model knees. All specimens were randomised into two treatment groups: (1) pullout repair using 1.3 mm suture tape (thin group, n = 10; 1.3 mm PERMATAPE, Mitek Sports Medicine) fixation and (2) pullout repair using 2.5 mm suture tape (thick group, n = 10; 2.5 mm PERMATAPE, Mitek Sports Medicine) fixation. The single‐loop stitch MS technique was utilised. The MST complex specimens were placed on a tensile tester. The structural properties of the MST complex (yield load, maximum load, liner stiffness, and elongation at failure) were identified.Results: No significant differences were found between the thin and thick groups in terms of maximum load (108.8 ± 49.6 vs. 90.1 ± 33.6 N; p = 0.34), yield load (43.8 ± 15.2 vs. 39.4 ± 15.5 N; p = 0.53), liner stiffness (12.6 ± 8.4 vs. 11.2 ± 5.5 N/mm; p = 0.45), and elongation at failure (27.1 ± 19.4 vs. 19.9 ± 10.0 mm; p = 0.32).Conclusion: The structural properties of the thickness of the different UHMWPE were comparable in MMPRT repair. Additionally, 1.3 mm PERMATAPE may demonstrate similar repair potential as 2.5 mm PERMATAPE.Level of Evidence: Level Ⅳ.

Purpose: Medial meniscus posterior root tears (MMPRT) pull-out repair aims to restore the meniscus’ anatomical structure. Different implants are utilized for thread fixation in the pull-out repair technique for MMPRT. However, biomechanical evidence comparing the fixation strengths of these implants remains unavailable. This study investigated the tensile strength of three fixation implants in porcine knee models of MMPRT pull-out repair. Methods: This study categorized 30 porcine MMPRT models undergoing pull-out repair into three groups (10 specimens each) based on the implant utilized for fixation, including double spike plate, metallic interference screw (IFS), and resorbable IFS fixed group. A tensile tester was used to track the suture wire threaded to the medial meniscus anterior root. The displacement length was recorded after 10 and 20 loading cycles (10–30 N, 100 mm/min cross-head speed). Each specimen was then stretched to failure (50 mm/min cross-head speed), failure modes were recorded, and structural properties (maximum load, linear stiffness, elongation at failure, and elongation at yield) were compared. Fisher’s exact test and one-way analysis of variance were utilized to assess the differences. Results: No significant differences in displacement length, upper yield load, maximum load, linear stiffness, elongation at yield, elongation at failure, and frequency of failure mode were observed between the three groups. Conclusion: All implants were comparable in terms of fixation strength. Thus, resorbable interference screws may be particularly useful in this technique and does not require implant removal surgery. Level of evidence: IV.

Introduction: Patient-specific instrumentation (PSI) systems are used to conduct total knee arthroplasty. PSI reduces operative time, is less invasive and easier to use, and minimizes the risk of errors by providing precise measurements and reducing operating room turnover time. However, a study on the accuracy of Prophecy Evolution PSI (Microport Inc., Arlington, TN, USA) reported that 94% were below the error margin of 1.5 mm and 90% had error margins of 1 mm. This study aimed to evaluate the accuracy of the Prophecy Evolution PSI system in terms of the thickness of “total” bony resection required to achieve adequate extension/flexion gaps and the component match ratio between preoperative planning and actual component size inserted. Methods: Comparisons were made between the sizes of femoral and tibial components planned with PSI and those inserted. The primary outcome was the average preoperative range of motion with and without matched femoral/tibial components. The study further analyzed the proportions of cases in which both the femoral and tibial components matched, neither matched, and only one of the femoral or tibial components matched. Results: The ratio of the same sizes between the PSI planning and those inserted was 50.8% (33 patients) for both the femoral and tibial components. For the femoral component alone, the ratio was 84.6% (55 patients), and for the tibial component, it was 58.4% (38 patients). A receiver-operating characteristic curve analysis indicated that flexion contracture greater than 20° was a significant prognostic factor for the PSI component match group versus the mismatch group. Discussion: Flexion contracture may cause PSI mismatch. Notably, flexion contracture greater than 20° was a significant risk factor for the PSI component match group versus the mismatch group. During preoperative planning for a patient with flexion contracture, surgeons should prepare for the possibility of inserting an undersized tibial component.