Graft Extrusion Related to the Position of Allograft in Lateral Meniscal Allograft Transplantation: Biomechanical Comparison Between Parapatellar and Transpatellar Approaches Using Finite Element Analysis.

PURPOSE: To compare the relation of extrusion of the graft with the position of the allograft between the parapatellar and transpatellar approaches and to show the primary importance of an anatomically correct position by comparing the chondroprotective effects after lateral meniscal allograft transplantation (MAT) with those of normal healthy knees. METHODS: Geometrical data from patients who underwent magnetic resonance imaging evaluation after lateral MAT were used as baseline input data for 3-dimensional and finite element analysis. The inclusion criteria were patients with symptomatic knees that had undergone meniscectomy who underwent lateral MAT with a minimum follow-up of 2 years. Patients with generalized arthritis, lower limb malalignment with greater than 5° valgus or varus, or uncorrected joint instability caused by ligament structure deficiency were excluded from this study. Patients were divided into the parapatellar group (25 patients) and transpatellar group (20 patients) according to surgical approach. RESULTS: The mean width of the extruded meniscus was 4.32 ± 0.58 mm in the parapatellar group and 3.00 ± 0.61 mm in the transpatellar group (P < .0001). The mean relative percentage of extrusion was 42.48% ± 7.82% in the parapatellar group and 28.21% ± 4.49% in the transpatellar group (P < .0001). The mean angle between the bony bridge and the center of the tibial plateau was significantly greater in the parapatellar group (16.69° ± 2.68°) than in the transpatellar group (5.29° ± 1.55°, P < .0001). The mean distance from the entry point of the bony bridge to the center of the tibial plateau was also greater in the parapatellar group (16.68 ± 2.56 mm) than in the transpatellar group (10.81 ± 1.37 mm, P < .0001). The distance from the entry point of the bony bridge to the center of the tibial plateau significantly influenced the obliquity of the bony bridge in the parapatellar group (P = .002). On finite element analysis, the transpatellar approach was more similar to the intact knee model in terms of the contact area and stress of the lateral meniscus and medial meniscus as well as the maximum compressive and maximum shear stresses. Compared with the parapatellar approach, the transpatellar approach had lower maximum contact stress on the menisci and lower maximum compressive stress and maximum shear stress on the femoral and tibial articular surfaces. CONCLUSIONS: The transpatellar approach led to a more anatomically correct positioning of the grafted meniscus with less meniscal extrusion than did the parapatellar approach in lateral MAT. Furthermore, the transpatellar model had lower maximum contact stress on the menisci than did the parapatellar model, and it also had lower maximum compressive stress and maximum shear stress on the femoral and tibial articular surfaces. CLINICAL RELEVANCE: The transpatellar approach is likely to have a more anatomic placement of graft with a subsequent greater chondroprotective effect; thereby, it may reduce the overall risk of degenerative osteoarthritis after lateral MAT.

Biomechanical comparison of fixed- and mobile-bearing for unicomparmental knee arthroplasty using finite element analysis.

Unicomparmental knee arthroplasty (UKA) is a popular alternative to total knee arthroplasty (TKA) and high tibial osteotomy for unicompartmental knee conditions, especially in young patients. However, failure of UKA occurs due to either progressive osteoarthritis (OA) in the other compartment or wear on the polyethylene (PE) insert. This study used finite element (FE) analysis to investigate the effects of PE insert contact pressure and stress in opposite compartments for fixed- and mobile-bearing UKA. Analysis was performed using high kinematics displacement and rotation inputs, which were based on the kinematics of the natural knee. ISO standards were used for axial load and flexion. The mobile-bearing PE insert had lower contact pressure than the fixed-bearing PE insert. With the mobile-bearing UKA, lower stress on the opposite compartment reduces the overall risk of progressive OA in the knee. The fixed-bearing UKA increases the overall risk of progressive OA in the knee due to higher stress on the opposite compartment. However, the PE insert of mobile-bearing showed pronounced backside stress at the inferior surface.

Mesenchymal stem cell injections improve symptoms of knee osteoarthritis.

PURPOSE: The purpose of this study was to evaluate the clinical and imaging results of patients who received intra-articular injections of autologous mesenchymal stem cells for the treatment of knee osteoarthritis. METHODS: The study group comprised 18 patients (6 men and 12 women), among whom the mean age was 54.6 years (range, 41 to 69 years). In each patient the adipose synovium was harvested from the inner side of the infrapatellar fat pad by skin incision extension at the arthroscopic lateral portal site after the patient underwent arthroscopic debridement. After stem cells were isolated, a mean of 1.18 × 10(6) stem cells (range, 0.3 × 10(6) to 2.7 × 10(6) stem cells) were prepared with approximately 3.0 mL of platelet-rich plasma (with a mean of 1.28 × 10(6) platelets per microliter) and injected into the selected knees of patients. Clinical outcome was evaluated with the Western Ontario and McMaster Universities Osteoarthritis Index, the Lysholm score, and the visual analog scale (VAS) for grading knee pain. We also compared magnetic resonance imaging (MRI) data collected both preoperatively and at the final follow-up. RESULTS: Western Ontario and McMaster Universities Osteoarthritis Index scores decreased significantly (P < .001) from 49.9 points preoperatively to 30.3 points at the final follow-up (mean follow-up, 24.3 months; range, 24 to 26 months). Lysholm scores also improved significantly (P < .001) by the last follow-up visit, increasing from a mean preoperative value of 40.1 points to 73.4 points by the end of the study. Likewise, changes in VAS scores throughout the follow-up period were also significant (P = .005); the mean VAS score decreased from 4.8 preoperatively to 2.0 at the last follow-up visit. Radiography showed that, at the final follow-up point, the whole-organ MRI score had significantly improved from 60.0 points to 48.3 points (P < .001). Particularly notable was the change in cartilage whole-organ MRI score, which improved from 28.3 points to 21.7 points (P < .001). Further analysis showed that improvements in clinical and MRI results were positively related to the number of stem cells injected. CONCLUSIONS: The results of our study are encouraging and show that intra-articular injection of infrapatellar fat pad-derived mesenchymal stem cells is effective for reducing pain and improving knee function in patients being treated for knee osteoarthritis. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Prognostic factors of arthroscopic pull-out repair for a posterior root tear of the medial meniscus.

BACKGROUND: Repair of a posterior root tear of the medial meniscus (MRT) decreases peak contact pressure by restoring hoop tension and is expected to prevent progression to osteoarthritis. PURPOSE: The purposes of this study were (1) to report the clinical and magnetic resonance imaging (MRI) results of arthroscopic pull-out repair of the MRT and (2) to identify prognostic factors of poor outcome. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Fifty-one patients (47 women, 4 men) who underwent arthroscopic pull-out repair of the MRT by a single surgeon were enrolled. Mean follow-up after surgery was 33 months (range, 24-44 months). To identify factors affecting final outcome, patient-specific factors, such as gender, age, body mass index, meniscus extrusion, extrusion increase, subchondral edema, degree of varus alignment (<5° or >5°), and cartilage status in the medial compartment (Outerbridge grade 1 or 2 lesion vs grade 3 or 4 lesion), were investigated. Final clinical outcomes were determined using a visual analog scale (VAS) for pain and patient satisfaction scores, American Knee Society (AKS) scores, and Lysholm scores, and MRI outcomes were determined by evaluating meniscus extrusion and articular cartilage status. Multiple regression analysis was performed to identify variables that independently affected clinical and MRI-determined outcomes. RESULTS: All clinical outcome measures significantly improved after surgery. Patients with Outerbridge grade 3 or 4 chondral lesions had poorer results than those with grade 1 or 2 lesions in terms of AKS function and Lysholm scores. Patients with varus alignment of >5° had poorer results than those with varus alignment of <5° in terms of VAS satisfaction, AKS function, and Lysholm scores. Mean meniscus extrusion increased from 3.6 mm preoperatively to 5.0 mm postoperatively. Chondral lesions progressed in 3 (9.7%) of 31 patients. Preoperative meniscus extrusion was found to be positively correlated with final extrusion. CONCLUSION: At a mean follow-up of 33 months after pull-out repair, extrusion of the meniscus was found to have progressed. Nevertheless, this technique provided patients with a clinical benefit. Outerbridge grade 3 or 4 chondral lesions and varus alignment of >5° were found to independently predict an inferior clinical outcome.

Arthroscopic pullout repair of posterior root tear of the medial meniscus: the anterior approach using medial collateral ligament pie-crusting release.

Posterior root tears of the medial meniscus are frequently encountered and should be repaired if possible to prevent osteoarthritis of the medial compartment. Various surgical techniques have been proposed to repair posterior root tears. The anterior arthroscopic approach can cause an iatrogenic chondral injury due to the narrow medial joint space. The posterior approaches might be technically unfamiliar to many surgeons because they require the establishment of a posteromedial or trans-septal portal. This paper describes the medial collateral ligament pie-crusting release technique for arthroscopic double transosseous pullout repair of posterior root tears of the medial meniscus through the anterior approach to provide the good visualization of the footprint and sufficient working space.

Peel-off injury at the tibial attachment of the posterior cruciate ligament in children.

BACKGROUND: Careful review of the literature seldom reveals peel-off-type injuries at the tibial attachment of the posterior cruciate ligament in children. PURPOSE: The purpose of this research is to describe the diagnosis and treatment of peel-off injuries at the tibial ligament-osseous junction of the posterior cruciate ligament in children. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Between February 2001 and May 2007, 6 patients with diagnosed peel-off injuries at the tibial attachment of the posterior cruciate ligament were surgically treated. All patients were boys from 12 to 13 years of age (mean, 12.3 years). Plain radiographs were normal, but magnetic resonance imaging and arthroscopic findings revealed complete avulsion of the posterior cruciate ligament at the tibial attachment without an osseous fragment. The authors retrospectively reviewed the clinical presentations, diagnostic tests, surgical procedures, and the results of the treatment. The mean follow-up was 37.3 months (range, 25-53 months). RESULTS: Five of the 6 patients had returned to their preinjury levels of activities. The mean side-to-side difference in posterior translation as measured with the KT-2000 arthrometer and stress radiographs was 2.3 mm (range, 0.7-5.2 mm) and 2.9 mm (range, 0.3-6.4 mm), respectively. The mean Lysholm score was 95 points (range, 90-100 points). According to the assessment with the International Knee Documentation Committee form, 2 patients were classified as A, 3 as B, and 1 as C. CONCLUSION: The authors could diagnose peel-off injuries at the tibial attachment of the posterior cruciate ligament in children by careful examinations and arthroscopic surgeries. Satisfactory outcomes without any complications were obtained through the arthroscopic reattachment and fixation using multiple sutures in the case of the avulsed stump that was not split.

Comparison of the clinical results of three posterior cruciate ligament reconstruction techniques.

BACKGROUND: Despite its technical complexity, arthroscopic tibial inlay reconstruction of the posterior cruciate ligament has biomechanical advantages over transtibial procedures. The purpose of this study was to compare the clinical results of arthroscopic tibial inlay single-bundle and double-bundle techniques with those of the conventional transtibial single-bundle technique. METHODS: We evaluated twenty-nine patients treated with primary posterior cruciate ligament reconstruction and followed for longer than two years. Eight patients were treated with a transtibial single-bundle procedure; eleven, with an arthroscopic inlay single-bundle procedure; and ten, with an arthroscopic inlay double-bundle procedure. An Achilles tendon allograft was used in all cases. Each patient was evaluated on the basis of the Lysholm knee score, the mean side-to-side difference in tibial translation as measured on Telos stress radiographs, and the side-to-side difference in the range of motion of the knee. RESULTS: The mean side-to-side difference (and standard deviation) in posterior tibial translation differed significantly between the arthroscopic tibial inlay double-bundle group (3.6 +/- 1.43 mm) and the transtibial single-bundle group (5.6 +/- 2.00 mm) (p = 0.023), although there was no significant difference between the arthroscopic inlay single-bundle group (4.7 +/- 1.62 mm) and the transtibial group (p = 0.374). The mean range of motion and Lysholm scores were similar among the three groups. CONCLUSIONS: Despite its technical difficulty, the arthroscopic tibial inlay double-bundle technique is our preferred method of reconstruction of the posterior cruciate ligament because it stabilizes posterior tibial translation better than do the other two methods.

Anterior cruciate ligament reconstruction with use of a single or double-bundle technique in patients with generalized ligamentous laxity.

BACKGROUND: In a patient with generalized ligamentous laxity, the risk of instability is greater with a conventionally reconstructed anterior cruciate ligament. The purpose of this study was to compare the clinical outcome of anterior cruciate ligament reconstruction done with a double-bundle technique with use of a quadriceps tendon-bone autograft and that of a single-bundle reconstruction with use of a bone-patellar tendon-bone autograft in patients with generalized ligamentous laxity. METHODS: The records of sixty-one patients who underwent anterior cruciate ligament reconstruction between June 2002 and October 2005 were evaluated. Thirty-two patients underwent a single-bundle reconstruction (group 1), and twenty-nine patients underwent a double-bundle reconstruction (group 2). Clinical outcomes were determined from data obtained before surgery and at the twenty-four-month follow-up visit. RESULTS: Postoperatively, the mean side-to-side difference (and standard deviation) in anterior tibial translation, measured with use of a KT-2000 arthrometer, was greater for group 1 (3.37 +/- 1.76 mm; range, 1.00 to 8.00 mm) than for group 2 (2.03 +/- 1.11 mm; range, 0.00 to 3.50 mm) (p = 0.02). Three patients in group 1 had a grade-1+ pivot shift, while no patient in group 2 had an abnormal pivot shift. The mean score on the Hospital for Special Surgery knee ligament questionnaire was 90.8 in group 1 and 92.1 in group 2, and the mean Lysholm score was 89.4 in group 1 and 91.1 in group 2. CONCLUSIONS: On the basis of the evaluation of ligamentous laxity measured by the KT-2000 arthrometer, a double-bundle anterior cruciate ligament reconstruction with use of a quadriceps tendon-bone autograft allows less anterior translation than does a single-bundle reconstruction with use of a bone-patellar tendon-bone autograft. However, we could not identify a significant difference in the functional outcome between the two techniques.

Comparison of single- and double-bundle anterior cruciate ligament reconstruction using quadriceps tendon-bone autografts.

PURPOSE: The purpose of this study was to evaluate and compare postoperative knee stability and functional scores between single- and double- bundle anterior cruciate ligament (ACL) reconstruction with the use of quadriceps tendon-bone autografts at a 2-year follow-up. METHODS: The records of 59 patients who had ACL reconstruction between January 2005 and April 2006 were analyzed retrospectively. Twenty-eight patients had single-bundle reconstruction (group S) and 31 received double-bundle reconstruction (group D). Ligament stability was assessed with the Lachman and pivot-shift tests and a KT-2000 arthrometer. International Knee Documentation Committee (IKDC) and Lysholm scores were employed to evaluate the functional outcomes. RESULTS: The postoperative mean side-to-side difference for group S was 2.64 mm and 1.79 mm for group D, a difference that was found to be statistically significant (P = .020). Regarding the pivot-shift test, 3 patients had grade 1+ and 1 patient had grade 2+ pivot-shift in group S, while no patients had abnormal pivot-shift in group D (P = .093). The patients who reported grade A or B on IKDC scores were 24 and 28 in group S and D, respectively (P > .1). On the questionnaire of the twisting activity, although statistical difference was not found between the groups, there was a trend toward more restriction in twisting activity in group S (P = .096). We found significant correlation between the twisting activity and instability questionnaire of the Lysholm score (Spearman coefficient, 0.737; P < .001). CONCLUSIONS: Double-bundle ACL reconstruction using quadriceps tendon-bone autografts provide less laxity (1.79 mm) than single-bundle ACL reconstruction (2.64 mm) as measured by the KT-2000. However, we could not find any significant differences in the functional measurements between the 2 groups. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

A modified arthroscopic anterior cruciate ligament double-bundle reconstruction technique with autogenous quadriceps tendon graft: remnant-preserving technique.

Several techniques of anterior cruciate ligament (ACL) double-bundle reconstruction have been introduced to improve the functional outcome and restore normal kinematics of the knee. Meanwhile, a remnant-preserving technique was developed to preserve the proprioception and to enhance the revascularization of the reconstructed ACL. We developed double-bundle ACL reconstruction technique using autogenous quadriceps tendon graft while preserving the remnant. With this technique, two femoral sockets and one tibial tunnel are made. To preserve the remnant of the ACL, the rotational direction of the reamer was set to counterclockwise just before perforation of the tibial tunnel. To pass the graft more easily without disturbance of the remnant, the graft passage was achieved through the tibial tunnel. We suggest that the remnant-preserving technique could be an effective alternative considering its mechanical stability as well as the proprioception and vascularization recovery in arthroscopic double-bundle ACL reconstruction.