Kyu Sung Chung

Are Muscle Strength and Function of the Uninjured Lower Limb Weakened After Anterior Cruciate Ligament Injury? Two-Year Follow-up After Reconstruction

Background: After an anterior cruciate ligament (ACL) injury, the uninjured contralateral lower limb may become weakened because of neuromuscular changes, proprioceptive deficits, and disuse of the limb; this weakness predisposes the limb to ACL injury. However, no results have been reported regarding weakness in the contralateral limb after ACL injury. Hypothesis: Muscle strength and functional status of the contralateral lower limb are reduced after unilateral ACL injury. Study Design: Cohort study; Level of evidence, 3. Methods: The ACL group consisted of 75 patients who underwent primary unilateral ACL reconstruction and were followed at 3, 6, 12, and 24 months postoperatively. A group of 75 healthy individuals (controls) were matched one-to-one with the ACL group for age, sex, body mass index, and initial Tegner activity level. The side that was evaluated in each control subject corresponded to the injured limb in the matched ACL subject. Isokinetic muscle strength, including extension peak torque per body weight (EPT) and flexion peak torque per body weight (FPT), was evaluated at angular velocities of 60 and 180 deg/s. Patients were also evaluated by single-legged hop test. Results: Compared with the EPT at 60 deg/s in the control group (290.9 ± 40.1 N·m/kg), the value in the ACL group 24-month follow-up (276.6 ± 42.8 N·m/kg) as well as other follow-up times was significantly lower (P < .05), whereas the EPT at 180 deg/s and the FPT at 60 and 180 deg/s in the ACL group were significantly lower than the control group at 3-month follow-up but were restored to normal levels at final follow-up. Results from the single-legged hop test demonstrated that the ACL group performed at a significantly lower level than the control group at 24-month follow-up (158.4 ± 25.3 vs 176.3 ± 24.7 cm; P < .05) as well as other follow-up times. However, both measurements improved significantly as the follow-up time progressed. Conclusion: After ACL injury, isokinetic extensor muscle strength and functional status of the contralateral limb were reduced, even at 24 months after ACL reconstruction. However, both measurements improved significantly as the follow-up time progressed. In contrast, flexion muscle strength was restored to normal levels. Therefore, care should be taken to restore muscle strength and functional status in not only the ACL-reconstructed knee but also the uninjured limb.

Pullout Fixation of Posterior Medial Meniscus Root Tears: Correlation Between Meniscus Extrusion and Midterm Clinical Results

Background: Medial meniscus posterior root tears (MMPRTs) lead to extrusion of the meniscus during weightbearing as well as loss of the ability of the meniscus to generate hoop stress. This loss of load-sharing ability leads to progressive arthritic changes. However, there have been no studies that correlate the correction of meniscus extrusion with clinical outcomes. Hypothesis: Decreased meniscus extrusion is associated with better clinical and radiographic outcomes compared with increased meniscus extrusion after MMPRT pullout fixation. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 39 patients who underwent MMPRT pullout fixation and had been observed for more than 5 years were recruited for this study. The mean follow-up period was 69.8 months. Participants were categorized into 2 groups according to the direction of meniscus extrusion: group A (increased extrusion; 23 patients) and group B (decreased extrusion; 16 patients). Meniscus extrusion was assessed in the coronal plane on magnetic resonance imaging preoperatively and at 1 year postoperatively. The postoperative clinical outcomes (Lysholm and International Knee Documentation Committee [IKDC] scores) and radiographic results (Kellgren-Lawrence [K-L] grade and medial joint space) were compared between groups. Results: Meniscus extrusion in group A increased significantly from a mean (±SD) of 3.5 ± 0.9 mm preoperatively to 5.1 ± 1.4 mm at 1 year postoperatively (P < .001), whereas in group B, it decreased significantly from 4.1 ± 1.3 mm preoperatively to 3.5 ± 1.4 mm at 1 year postoperatively (P < .001). The K-L arthritis grade (0/1/2/3/4) significantly progressed in group A (from 2/12/9/0/0 preoperatively to 0/1/14/8/0 postoperatively, respectively; P = .009) but not in group B (from 1/11/4/0/0 preoperatively to 0/6/8/2/0 postoperatively, respectively; P = .274). The mean final Lysholm and IKDC scores in group B (88.1 ± 12.1 and 79.0 ± 11.4, respectively) were significantly better than those in group A (81.0 ± 9.0 and 71.1 ± 7.8, respectively) (P < .05). There was less medial joint space narrowing at final follow-up in group B (0.6 ± 0.8 mm) than in group A (1.1 ± 0.6 mm) (P = .015). Progression of the K-L arthritis grade was seen in 50% (8/16) of the patients in group B compared with 87% (20/23) of the patients in group A (P = .027). Conclusion: The current study demonstrates that in patients with MMPRTs, pullout fixation leads to favorable midterm outcomes, regardless of meniscus extrusion at 1-year follow-up. However, patients with decreased meniscus extrusion at postoperative 1 year have more favorable clinical scores and radiographic findings at midterm follow-up than those with increased extrusion at 1 year. This study indicates that one of the main goals of the repair of MMPRTs is to reduce meniscus extrusion as much as possible.

Arthroscopic Medial Meniscal Allograft Transplantation with Modified Bone Plug Technique

The meniscal allograft transplantation (MAT) has been reported to be an effective treatment in terms of pain relief and functional improvement in symptomatic meniscus-deficient knee. The medial MAT is usually performed with the bone plug technique or soft tissue fixation for root fixation. We describe medial MAT with modified bone plug technique that permits easy passage of posterior bone plugs and facilitates bone-to-bone healing. With this method, an anterior bone plug with a long cylindrical shape is prepared, and the posterior bone plug is prepared with a flat bone shell containing a cancellous portion. This modified technique facilitates graft passage as well as bone-to-bone healing.

Arthroscopic Lateral Meniscal Allograft Transplantation With the Key-Hole Technique

The efficacy of meniscus allograft transplantation (MAT) for the meniscus-deficient knee has been widely recognized as being excellent in terms of pain relief and functional improvement. Lateral MAT is usually performed with the bone bridge technique that uses a bone bridge connecting the anterior and posterior horns of an allograft. The slot position for the meniscal graft insertion is of great importance with the bone bridge technique, especially in the key-hole method. The purpose of this Technical Note is to describe lateral MAT using the key-hole technique in which an allograft with a bone bridge carved to accommodate the key-hole-shaped slot is properly secured to the slot.

Comparison of Poly-L-Lactic Acid and Poly-L-Lactic Acid/Hydroxyapatite Bioabsorbable Screws for Tibial Fixation in ACL Reconstruction: Clinical and Magnetic Resonance Imaging Results

Background The purpose of this study was to compare the clinical and radiological results of 2 different tibial fixations performed using bioabsorbable screws with added hydroxyapatite (HA) and pure poly-L-lactic acid (PLLA) screws in anterior cruciate ligament (ACL) reconstruction. Methods A total of 394 patients who underwent arthroscopic ACL reconstruction between March 2009 and June 2012 were retrospectively reviewed. Of those, 172 patients who took the radiological and clinical evaluations at more than 2 years after surgery were enrolled and divided into 2 groups: PLLA group (n = 86) and PLLA-HA group (n = 86). Both groups were assessed by means of the Lysholm score, International Knee Documentation Committee (IKDC) subjective knee score, and Tegner activity score. Stability was evaluated using the KT-2000 arthrometer. Magnetic resonance imaging was performed to evaluate tibial tunnel widening, screw resorption, osteoingeration, and foreign body reactions. Results The PLLA-HA group showed significant reduction in the extent of tibial tunnel widening and foreign body reactions and significant increase in screw resorption compared to the pure PLLA group (p < 0.001 for both). In contrast, postoperative Lysholm score, Tegner activity score, IKDC score, and side-to-side difference on the KT-2000 arthrometer showed no significant differences between groups (p = 0.478, p = 0.906, p = 0.362, and p = 0.078, respectively). The PLLA group showed more significant widening in the proximal tibial tunnel than the PLLA-HA group (p = 0.001). In the correlation analysis, proximal tibial tunnel widening revealed a positive correlation with knee laxity (r = 0.866) and a negative correlation with Lysholm score (r = −0.753) (p < 0.01 for both). Conclusions The HA added PLLA screws would be advantageous for tibial graft fixation by reducing tibial tunnel widening, improving osteointegration, and lowering foreign body reactions. Even though no clinically significant differences were noted between the pure PLLA group and PLLA-HA group, widening of the proximal area of the tibial tunnel showed a tendency to increase knee laxity measured using the KT-2000 arthrometer.

Arthroscopic Medial Meniscus Posterior Root Reconstruction Using Auto-Gracilis Tendon

There have been several techniques to repair the medial meniscus posterior root tears (MMPRTs) with the goal of restoring the anatomic and firm fixation of the meniscal root to bone. Many anatomic studies about the menisci also have been developed, so a better understanding of the anatomy could help surgeons perform correct fixation of the MMPRTs. The meniscal roots have ligament-like structures that firmly attach the menisci to the tibial plateau, and this structural concept is important to restore normal biomechanics after anatomic root repair. We present arthroscopic transtibial medial meniscus posterior root reconstruction using auto-gracilis tendon.

Biomechanical Analysis of a Novel Wedge Locking Plate in a Porcine Tibial Model

Background The purpose of this study was to analyze biomechanical properties of a novel wedge locking plate in medial open wedge high tibial osteotomy (OWHTO) in a porcine tibial model. Methods A uniform 8-mm OWHTO was performed in 12 porcine tibiae. Six of them were subsequently fixed with the plate without a wedge, whereas the other 6 were additionally reinforced with a metal wedge of 8 mm. Biomechanical properties (stiffness, displacement of the osteotomy gap, and failure load) were evaluated under axial load. The different modes of failure were also investigated. Results The plate showed an axial stiffness of 2,457 ± 450 N/mm with a wedge and 1,969 ± 874 N/mm without a wedge. The maximum failure load was 5,380 ± 952 N with a wedge and 4,354 ± 607 N without a wedge. The plate with a wedge had a significantly greater failure load and significantly less displacement of medial gap at failure than that without a wedge (p = 0.041 and p = 0.002, respectively). The axial stiffness was not different between the two types of fixation. Most failures were caused by lateral cortex breakage and there was no implant failure. Conclusions The novel wedge locking plate showed excellent biomechanical properties and an additional wedge provided significant improvement. This plate can be a good fixation method for OWHTO.