Michael P. Bradley

Effects of Initial Graft Tension on the Tibiofemoral Compressive Forces and Joint Position After Anterior Cruciate Ligament Reconstruction

Background The initial tension applied to an anterior cruciate ligament graft at the time of fixation modulates knee motion and the tibiofemoral compressive loads. Purpose To establish the relationships between initial graft tension, tibiofemoral compressive force, and the neutral tibiofemoral position in the cadaveric knee. Study Design Controlled laboratory study. Methods The tibiofemoral compressive forces and joint positions were determined in the anterior cruciate ligament-intact knee at 0°, 20°, and 90° of knee flexion. The anterior cruciate ligament was excised and reconstructed with a patellar tendon graft using graft tensions of 1, 15, 30, 60, and 90 N applied at 0°, 20°, and 90° of knee flexion. The compressive forces and neutral positions were compared between initial tension conditions and the anterior cruciate ligament-intact knee. Results Increasing initial graft tension increased the tibiofemoral compressive forces. The forces in the medial compartment were 1.8 times those in the lateral compartment. The compressive forces were dependent on the knee angle at which the tension was applied. The greatest compressive forces occurred when the graft was tensioned with the knee in extension. An increase in initial graft tension caused the tibia to rotate externally compared with the anterior cruciate ligament-intact knee (1.5° and 7.7° of external rotation when tensioned to 90 N at 0° and 90° of knee flexion, respectively). Increases in initial graft tension also caused a significant posterior translation of the tibia relative to the femur (0.9 and 5.3 mm of posterior translation when tensioned to 90 N at 0° and 90° of knee flexion, respectively). Conclusion Different initial graft tension protocols produced predictable changes in the tibiofemoral compressive forces and joint positions. Clinical Relevance The tibiofemoral compressive force and neutral joint position were best replicated with a low graft tension (1-15 N) when using a patellar tendon graft.

Porcine Small Intestine Submucosa for Repair of Goat Meniscal Defects

This study evaluated the effectiveness of small intestine submucosa used as a graft to fill surgically created meniscal defects in a large animal model. Four goats underwent unilateral interior subtotal meniscectomies (approximately 70%) within the avascular portion of the medial meniscus. The contralateral meniscus acted as a control. Grafts of porcine small intestine submucosa were trimmed to fill the resected defects and sutured into place. After surgery the operated knees were casted in partial flexion to limit weight bearing on the affected limb. All of the animals were sacrificed at 12 weeks at which point meniscal regeneration and articular cartilage degradation were evaluated by gross and histologic examination. Grossly, the defects in the small intestine submucosa-grafted goats were partially filled with meniscal-appearing connective tissue. Histologically, the replacement tissue was typified by the presence of dense, cellular, irregularly organized connective tissue. Evaluation of the articular cartilage displayed increased degeneration in the grafted compartment of the operative knees. Each of the operative menisci partially regenerated. The grafts were conducive to repopulation with host meniscal elements. Despite partial meniscal regeneration, comparatively more articular cartilage degeneration in the treated knees was observed than in the untreated contralateral controls.

The Diagnostic Value of MRI in Foot and Ankle Surgery

Background: MRI is being used with increasing frequency and seems to have become more popular as a screening tool rather than as an adjunct to narrow specific diagnoses or plan operative interventions. Our hypothesis was that the rising accessibility of this test may be resulting in its overuse. Methods: We retrospectively reviewed 221 consecutive patients referred over a 3-month period for treatment of a lower extremity problem to determine: (1) the number of patients who presented with an MRI already obtained from an outside source, (2) the number of patients who obtained an MRI from the foot and ankle specialist after referral, and (3) the number of times the foot and ankle specialist used these studies or found them helpful in the care of the patient. Fractures (20) were excluded. Results: Of the 201 patients without fractures included in the study, 19.9% (40 of 201) had MRI scans during the course of their treatment; 15.4% (31 of 201) presented to their initial visit with an MRI scan from an outside source, and 4.5% (9 of 201) received MRI scans as ordered by the foot and ankle specialist. Eighty-seven percent (27 of 31) of the pre-referral MRI scans were thought to be unnecessary, and 48.4% (15 of 31) had radiographic interpretations that were considered either immaterial to the patients pertinent clinical diagnosis or inconsistent with the specialists interpretations. All nine MRI scans ordered by the specialist were useful in the care of the patient. Therefore, of the 221 consecutive patients, the foot and ankle specialist would have ordered MRI scans in only 5.9% (13 of 221). Conclusions: This study suggests that many of the pre-referral foot or ankle MRI scans obtained before evaluation by a foot and ankle specialist are not necessary. Further studies need to be performed to determine the role of MRI in the screening of foot and ankle disorders.

A comparison of prospective and retrospective assessment of functional outcome after rotator cuff repair

Prospective outcome studies are generally considered to be better than retrospective studies. The purpose of this study was to assess correlations between prospective and retrospective outcome assessment after rotator cuff repair. One-hundred and twelve patients (118 shoulders) with chronic rotator cuff tears were evaluated at a mean of 54 months (34-85) after rotator cuff repair, using several outcome measures including a retrospective assessment of improvement. The retrospective assessment of post-operative pain, function, and quality of life had fair correlations with the prospectively determined improvement (R = .23-.25, P < .01). Post-operative patient satisfaction was more highly correlated with all retrospective evaluations than with the prospective improvement in all functional outcome measures. Retrospective and prospective evaluations of the outcome of rotator cuff repair are different. Patient satisfaction has a greater correlation with retrospective outcomes. Retrospective evaluation may aid in supplementing prospective evaluations, as it may better reflect a patients perception of the success after surgery.