Hee Sung Lee

Yoon KH, et al. Clin Orthop Surg. 2023 Sep;15:e65. https://doi.org/10.4055/cios22344

This study aimed to compare the clinical and radiological outcomes of medial patellofemoral ligament reconstruction (MPFLR) between anatomic femoral tunnel positions at anterior and posterior footprints. Fifty-seven patients who underwent MPFLR for patellofemoral instability with anterior or posterior femoral tunnels between 2014 and 2021 with at least 2 years of follow-up were retrospectively analyzed. Based on postoperative images, the femoral tunnel positions anterior to the line connecting the adductor tubercle and medial epicondyle were assigned to the anterior group, group A, and those posterior to the line to the posterior group, group P. Thirty-two patients were included in group A (mean age, 22.4 ± 8.8 years), and another 25 patients were included in group P (mean age, 21.1 ± 6.1 years). The International Knee Documentation Committee (IKDC) subjective score, Lysholm score, Tegner activity score, Kujala score, and complications were evaluated. Radiologically, the Caton–Deschamps index (CDI), patellar tilt angle, and patellofemoral osteoarthritis (PFOA) using the Kellgren–Lawrence (KL) scale were evaluated. The patellofemoral cartilage status according to the International Cartilage Repair Society (ICRS) grade, bone contusion, femoral tunnel enlargement, and MPFL graft signal intensity were also evaluated. All clinical scores significantly improved in both groups (p < 0.01). No differences were noted between the two groups in terms of their preoperative demographic data, postoperative clinical scores (IKDC, Lysholm, Tegner, and Kujala), complications, or radiological findings (CDI, patellar tilt angle, PFOA, bone contusion, femoral tunnel enlargement, and graft signal intensity). The ICRS grade for the medial facet of the patella progressed in group A (30%, p = 0.02) but not in group P (18%, p = n.s.). Additionally, no significant differences were observed in the other compartments of the patellofemoral joint. The clinical outcomes were significantly improved in both groups; however, MPFLR with anterior femoral tunnel position had worse cartilage status on the medial facet of the patella than the posterior femoral tunnel position. Level III.

Yoon KH, et al. Clin Orthop Surg. 2022 Dec;14:e105. https://doi.org/10.4055/cios22102

Weakening muscle strength around the knee tends to render it vulnerable to aging-related damage. This study aimed to examine the association between knee flexor muscle strength and its cross-sectional area (CSA). We also evaluated aging-related changes in flexor muscle strength and CSA. We retrospectively analyzed 252 patients with acute-onset knee pain (2 for the SM, 444.7 mm² for the biceps femoris, 282 mm² for the sartorius, 55.4 mm² for the ST, and 34.1 mm² for the gracilis. Mean peak torques were 67.4 N.m and 52.7 N.m at 60°/second and 180°/second, respectively. CSA was positively correlated with flexion strengths of 60°/second (R = 0.363, P < .001) and 180°/second (R = 0.354, P < .001). Muscle strength was associated with CSA in all muscles but the gracilis (R = 0.056, P = .375). Flexion strength decreased significantly with aging from the thirties. Total CSA decreased with aging (r = −0.247, P < .001). The CSA of the biceps femoris, sartorius, SM, and ST decreased significantly, whereas that of the gracilis tended to decrease non-significantly with aging. Flexor muscle strength was associated with total muscle CSA on magnetic resonance imaging and the CSA of every muscle except the gracilis. Flexion strength decreased significantly with aging after the twenties, while total CSA decreased significantly with aging. The CSA of all flexor muscles decreased significantly with aging, whereas that of the gracilis decreased only slightly.

Background: We aimed to study the association between flexor muscle strength in the knee joint and cross-sectional area (CSA) on magnetic resonance imaging (MRI). We also evaluated aging-related changes in flexor muscle strength and CSA. We hypothesized that muscle strength is associated with muscle CSA on MRI and that such relationships would differ among the flexor muscles. Furthermore, we hypothesized that muscle strength and CSA would decline, and the reduced rate of muscle CSA would differ among the flexor muscles with aging.Methods: A total of 252 patients (mean age, 33.6 years; range, 11–66 years) who visited the outpatient clinic with knee pain between September 2006 and August 2009 were retrospectively analyzed. The CSA of each knee joint flexor muscle (biceps femoris, sartorius, gracilis, semitendinosus, and semimembranosus) was measured on MRI axial images at the supra-patellar level. We evaluated flexor muscle strength (peak torque, N.m) using a Cybex dynamometer at 60 and 180°/s and evaluated its correlation with CSA.Results: Mean CSA was 605.4 mm² for the semimembranosus, 444.7 mm² for the biceps femoris, 282 mm² for the sartorius, 55.4 mm² for the semitendinosus, and 34.1 mm² for the gracilis. Mean peak torque was 67.4 N.m and 52.7 N.m at 60°/s and 180°/s, respectively. CSA was positively correlated with flexion strengths of 60°/s (r = 0.363, p = 0.000) and 180°/s (r = 0.354, p = 0.000). Muscle strength was associated with CSA for all muscles, except the gracilis (r = 0.056, p = 0.375). Flexion strength decreased significantly with age after the third decade of life. Total CSA decreased with age (r = −0.247, p = 0.000). CSA of the biceps femoris, sartorius, semimembranosus, and semitendinosus decreased significantly, while CSA of the gracilis tended to decrease non-significantly with aging.Conclusions: Muscle strength was associated with total muscle CSA on MRI and the CSA of every muscle but the gracilis. Flexion strength decreased significantly with aging after the third decade of life. Total CSA decreased significantly with aging. CSA of the biceps femoris, sartorius, semimembranosus, and semitendinosus decreased significantly, whereas that of the gracilis decreased slightly with aging.Level of Evidence: Level III, retrospective comparative study