Functional testing provides unique insights into the pathomechanics of femoroacetabular impingement and an objective basis for evaluating treatment outcome.

Femoroacetabular impingement (FAI) has been recognized as a significant clinical problem. While hip reshaping surgery for treating FAI has had positive clinical outcomes, there remains a need for objective functional outcomes of FAI treatment. We tested the hypothesis that during walking and stair climbing significant changes in hip kinematics would occur following hip reshaping surgery that indicate restoration of normal function post-operatively. Hip and pelvic kinematics were collected for 17 FAI patients pre- and 1 year post-operatively and compared to 17 healthy matched controls. Prior to surgery, FAI patients had significantly reduced hip internal rotation and hip sagittal plane range of motion during walking (p = 0.01, p < 0.001, respectively) and stair climbing (p = 0.01, p < 0.001, respectively) as compared with controls. Post-operatively, these motions were restored to normal during walking (p = 0.70, p = 0.46, respectively), but remained significantly reduced in the FAI patients during stair climbing (p = 0.03, p < 0.001, respectively). These results have important implications for understanding the functional pathomechanics of FAI and providing an objective basis for evaluating treatment outcome. The stair climbing results indicate that problems still exist in the hip joint for activities requiring higher ranges of hip motion and suggest a basis for exploring future improvements for the treatment of FAI.

Biomechanical evaluation of a novel reverse coracoacromial ligament reconstruction for acromioclavicular joint separation.

BACKGROUND: Enhancing anterior-posterior (AP) stability in acromioclavicular (AC) reconstruction may be advantageous. PURPOSE: To compare the initial stability of AC reconstructions with and without augmentation by either (1) a novel "reverse" coracoacromial (CA) ligament transfer or (2) an intramedullary AC tendon graft. HYPOTHESIS: Reverse CA transfer will improve AP stability compared with isolated coracoclavicular (CC) reconstruction. STUDY DESIGN: Controlled laboratory study. METHODS: Six matched pairs of cadaveric shoulders underwent distal clavicle resection and CC reconstruction. Displacement (mm) was measured during cyclic loading along AP (±25 N) and superior-inferior (SI; 10-N compression, 70-N tension) axes. Pairs were randomized to receive each augmentation and the same loading protocol applied. RESULTS: Reverse CA transfer (3.71 ± 1.3 mm, standard error of the mean [SEM]; P = .03) and intramedullary graft (3.41 ± 1.1 mm; P = .03) decreased AP translation compared with CC reconstruction alone. The SI displacement did not differ. Equivalence tests suggest no difference between augmentations in AP or SI restraint. CONCLUSION: Addition of either reverse CA transfer or intramedullary graft demonstrates improved AP restraint and provides similar SI stability compared with isolated CC reconstruction. CLINICAL RELEVANCE: Reverse CA ligament transfer may be a reasonable alternative to a free tendon graft to augment AP restraint in AC reconstruction.

Preoperative and postoperative sagittal plane hip kinematics in patients with femoroacetabular impingement during level walking.

BACKGROUND: Femoroacetabular impingement (FAI) has been linked to osteoarthritis. Treatment options range from nonoperative to operative, and current outcome measures are generally subjective or not conducted under actual activities of daily living. Thus, there is a need for the use of motion capture techniques to quantitatively assess the outcome of surgical intervention for those treated for FAI. HYPOTHESIS: The gait of FAI patients 1 year after operative treatment (arthroscopic hip reshaping) will be significantly closer to the normal range and pattern of hip flexion motion, relative to pretreatment. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Eleven patients between 18 and 44 years of age with diagnosed FAI were enrolled in this study. Kinematics and kinetics for this group of patients were collected using motion capture techniques before arthroscopic bone-reshaping surgery and again 1 year after surgery. Pain and perceived activity level (Tegner scale) were also collected. All collected data were compared using a paired t test. RESULTS: Overall hip sagittal plane range of motion increased on the affected side from 27.6° ± 5.0° to 30.7° ± 4.3° (P = .02). The presence of abnormal reversals (second-order change in the slope in the hip flexion/extension curve) that was present in 5 patients preoperatively disappeared or was reduced in prevalence and magnitude in 4 of the patients postoperatively. Additionally, pain decreased and activity level increased postoperatively. CONCLUSION: The results supported the hypothesis that surgical intervention for FAI restores more normal patterns of gait and provides objective support that the surgical procedure is useful. The results help establish motion capture as a potential method for quantitatively assessing the outcome in FAI surgical interventions. The presence of abnormal reversals in hip flexion has been reported in end-stage hip osteoarthritis, and the presence of these reversals in FAI patients reinforces the idea of FAI being a precursor to hip osteoarthritis.

Hip instability: anatomic and clinical considerations of traumatic and atraumatic instability.

Hip instability is uncommon because of the substantial conformity of the osseous femoral head and acetabulum. It can be defined as extraphysiologic hip motion that causes pain with or without the symptom of hip joint unsteadiness. The cause can be traumatic or atraumatic, and is related to both bony and soft tissue abnormality. Gross instability caused by trauma or iatrogenic injury has been shown to improve with surgical correction of the underlying deficiency. Subtle microinstability, particularly from microtraumatic or atraumatic causes, is an evolving concept with early surgical treatment results that are promising.

Case report: Bifid iliopsoas tendon causing refractory internal snapping hip.

BACKGROUND: Treatment of painful internal snapping hip (coxa saltans) via arthroscopic lengthening or release of the iliopsoas tendon is becoming preferred over open techniques because of the benefits of minimal dissection, the ability to address concomitant intraarticular disorders, and a low complication rate. Persistent snapping after release is uncommon, especially when performed arthroscopically. Reported causes include incomplete release, intraarticular disorders, and incorrect diagnosis. Anatomic variants are not discussed in the orthopaedic literature. CASE DESCRIPTION: We report a case of an 18-year-old softball player with internal snapping hip treated with arthroscopic iliopsoas release in the peripheral compartment. Postoperatively, the athlete continued to have painful snapping. Repeat arthroscopy with a larger capsulotomy revealed a bifid iliopsoas tendon causing refractory internal snapping hip, which resolved after revision arthroscopic release. LITERATURE REVIEW: Bifid iliopsoas tendon as a cause of persistent snapping of the hip has not been reported in the orthopaedic literature. Prior sonographic and anatomic studies suggest the bifid iliopsoas tendon exists but is uncommon. PURPOSE AND CLINICAL RELEVANCE: Recognition that a bifid iliopsoas tendon may be the source of painful internal snapping hip is important to prevent clinical failure of surgical management of the internal snapping hip. The differential diagnosis of failed iliopsoas lengthening surgery should include the consideration of an incompletely lengthened tendon attributable to bifid iliopsoas tendon anatomy. Prevention of this complication includes making a large enough capsulotomy to identify the tendon and to ensure it is not bifid.

Incidence of radiographic unicompartmental arthritis in patients undergoing knee arthroplasty.

Unicompartmental knee arthroplasty is increasing in popularity with the advent of less invasive procedures for knee arthritis. The percentage of patients undergoing knee arthroplasty who could be candidates for unicompartmental knee arthroplasty depends on the surgeon's evaluation of the radiographs, and this evaluation may depend on the surgeon's bias regarding partial knee arthroplasty. A retrospective radiographic and chart review was performed on a consecutive series of patients who had undergone tricompartmental knee arthroplasty to determine the percentage of those patients who could have been candidates for unicompartmental knee arthroplasty. Two hundred eighty-eight patients who underwent 308 tricompartmental knee arthroplasties over a 3-year period at a Veteran's Administration Hospital comprised the study group. Assessment of preoperative radiographs was done by 2 surgeons, 1 who favored unicompartmental knee arthroplasty and the other who preferred tricompartmental knee arthroplasty, to determine the percentage of these patients, from each surgeon's viewpoint, who had unicompartmental arthritis. Patients who had radiographic unicompartmental arthritis were then eliminated as candidates for unicompartmental knee arthroplasty, if, on chart review, they had a flexion contracture >10°, an arc of motion <100°, or inflammatory arthritis. The surgeon who was a proponent of unicompartmental knee arthroplasty found that 26% of these patients had acceptable radiologic and clinical indications for unicompartmental knee arthroplasty, whereas the surgeon who had a bias against the procedure felt that only 12% of these patients were unicompartmental knee arthroplasty candidates. A considerable percentage of Veteran's Administration patients undergoing arthroplasty for knee arthritis may be potential candidates for unicompartmental knee arthroplasty, despite the surgeon's bias for or against the procedure.