Several studies have shown the relationship between poorer clinical outcomes of arthroscopic femoroacetabular impingement syndrome surgery and focal chondral defects or global chondromalacia/osteoarthritis. Although recent studies described good outcomes after the conjunctive application of synovial mesenchymal stem cells (MSCs), none demonstrated the application of synovial MSCs for cartilaginous hip injuries. To compare the characteristics of MSCs derived from the paralabral synovium and the cotyloid fossa synovium and determine which is the better source. Controlled laboratory study. Synovium was harvested from 2 locations of the hip—paralabral and cotyloid fossa—from 18 donors. The number of cells, colony-forming units, viability, and differentiation capacities of adipose, bone, and cartilage were collected and compared between groups. In addition, real-time polymerase chain reaction was used to assess the differentiation capacity of adipose, bone, and cartilage tissue from both samples. The number of colonies and yield obtained at passage 0 of synovium from the cotyloid fossa was significantly higher than that of the paralabral synovium (P < .01). In adipogenesis experiments, the frequency of detecting oil red O–positive colonies was significantly higher in the cotyloid fossa than in the paralabral synovium (P < .05). In osteogenesis experiments, the frequency of von Kossa and alkaline phosphatase positive colonies was higher in the cotyloid fossa synovium than in the paralabral synovium (P < .05). In chondrogenic experiments, the chondrogenic pellet culture and the gene expressions of COL2a1 and SOX9 were higher in the cotyloid fossa synovium than in the paralabral synovium (P < .05). MSCs from the cotyloid fossa synovium have higher proliferation and differentiation potential than do those from the paralabral synovium and are therefore a better source. Synovial cells from the cotyloid fossa synovium of patients with femoroacetabular impingement syndrome are more robust in vitro, suggesting that MSCs from this source may be strongly considered for stem cell therapy.

Patellar tendon ruptures are severe but uncommon injuries that require surgical treatment. Primary repair for acute patellar tendon ruptures using augmentation techniques has shown good results in terms of biomechanical and clinical outcomes. This Technical Note details patellar tendon repair with suture tape augmentation for proximal patellar tendon rupture. Because this surgical technique does not require harvesting of the hamstring tendon and hardware removal, it is minimally invasive. In addition, it is simple and quick to perform. Technique Video: video See video under supplementary data.

Hypermobile meniscus is known as one of the causes of knee pain and locking or limitation of the range of motion during knee flexion, even when there is no evidence of meniscus tear on magnetic resonance imaging (MRI). Most such cases show excessive hypermobility of the posterior part of the lateral meniscus. This case report presented a rare case of a hypermobile anterior horn of the lateral meniscus. An 18-year-old woman visited our hospital for left knee pain without trauma. Her physical examination showed a limited range of motion and tenderness in the lateral joint space. However, her MRI did not show any abnormalities. After conservative treatment failed, we performed arthroscopic surgery. The arthroscopic evaluation showed no meniscus and no other intraarticular injury. However, the anterior horn of the lateral meniscus was easily translated beyond the lateral condyle by using a probe. Thus, hypermobile anterior horn of the lateral meniscus was diagnosed. The meniscus was stabilized by the outside-in technique. Immediately after surgery, the catching symptom and pain were alleviated. After three-and-a-half months, she returned to work. The Lysholm score improved from 55, preoperatively, to 100, 1-year postoperatively. In conclusion, careful arthroscopic evaluation is essential for the diagnosis of a hypermobile anterior horn of the lateral meniscus. Arthroscopic meniscus stabilization provides a good outcome for hypermobile meniscus.

Osteochondritis dissecans (OCD) of the knee is an uncommon injury in young active patients. There is currently a lack of knowledge regarding clinical outcomes and return-to-sport rates after fragment fixation surgery using hydroxy appetite poly-L-lactic acid (HA/PLLA) threaded pins for knee OCD among athletes. Our purpose was to investigate the clinical outcomes and return-to-sport rates following osteochondral fragment fixation using HA/PLLA pins for the treatment of knee OCD lesions among athletes. A total of 45 patients were retrospectively reviewed. In total, 31 patients were excluded, and 14 patients were included. Pre- and postoperative patient-reported outcome scores (PROSs), including the International Knee Documentation Committee (IKDC) score and Knee Injury and Osteoarthritis Outcome Scale (KOOS), were compared. In addition, patients were categorized into four groups according to postoperative sports status: higher, same, lower than preinjury, or unable to return to sports. The mean age was 14.4 years (SD 1.67). All patients were male. All PROSs significantly improved at 6, 12, and 24 months postsurgery compared to presurgery. 50% of the patients returned to sports at the same or higher level after surgery. Fragment fixation using HA/PLLA pins leads to favorable clinical outcome scores and high return-to-sport rates in the treatment of athletes with knee OCD.

A medial collateral ligament (MCL) tear is common in cases of isolated injury or in those combined with anterior cruciate ligament injury. Although conservative treatment for an MCL tear is popular, some cases result in residual instability. Thus, the treatment approach of grade III MCL injury remains controversial. In this Technical Note, we present the technique of arthroscopic primary MCL repair with suture anchor. With this technique, proximal MCL injuries can be repaired with minimal invasion. This technique improves valgus stability and enables early rehabilitation, including range of motion and weight‐bearing exercise. Technique Video: video See video under supplementary data.

This study aimed to investigate the associations between hip cartilage lesions and bony morphologic parameters in the hip joints using a computed tomography-based software system. Seventy-nine symptomatic hips that underwent hip arthroscopic labral preservation surgery were enrolled in this study. Bony structural morphologic parameters were subsequently assessed via a computed tomography-based software system. The indices included the femoral neck anteversion (FNA), alpha angle (AA) at each o'clock position of the femoral head, lateral center-edge angle (LCEA), and three-dimensional acetabular coverage (3D-AC). Cartilage damage was confirmed arthroscopically and classified according to the Multicenter Arthroscopy of the Hip Outcome Research Network (MAHORN) classification as well as the International Cartilage Repair Society classification. Of the 79 hips, 41 patients were male, and 38 were female, with a mean age of 39.1 years ​±16.1 years (11-78). The mean LCEA was 27.6° ​± ​8.6° (range 7°-46°), and the mean FNA was 22.9° ​± ​14.4° (range -2°-63°). Grade 4 or 5 MAHORN acetabulum cartilage lesions were observed in 10 hips (13 ​%), while femoral head cartilage lesions with ICRS grade of 3 or 4 were found in 10 hips. Patients with MAHORN grade 4 or 5 cartilage lesions had significantly greater FNA compared with those with MAHORN grade 0 to 3 lesions (32.6° ​± ​10.3° versus 21.4° ​± ​14.4°, p ​= ​0.009). Although patients with MAHORN grade 4 or 5 lesions had greater AA at the entire o'clock of the femoral neck, the difference was not statistically significant. Patients whose FNAs were 26° or larger had a 6.2-fold greater odds ratio (95 ​% confidence interval, 1.2-31.5) of acetabular cartilage damage than those whose FNAs were less than 26° (p ​= ​0.015). The use of computed tomography-based software provided detailed insights into bony abnormalities reinforcing its utility in evaluating hip joint pathologies and their relationship with cartilage lesions. Level III.