Electromyographic activity of selected scapular stabilizers during glenohumeral internal and external rotation contractions.

HYPOTHESIS: An important synergistic relationship exists between the scapular stabilizers and the glenohumeral rotators. Information on the relative contribution of the scapular stabilizers to glenohumeral rotation would be useful for exercise prescription for overhead athletes and for patients with shoulder pathology. We hypothesized that the scapular stabilizers would be highly active during both maximal and submaximal internal and external rotation. MATERIALS AND METHODS: Eight healthy male volunteers (16 shoulders) performed internal and external glenohumeral rotation testing at maximal and submaximal intensities. They also performed a scapular retraction rowing exercise at maximal and submaximal levels. Electromyographic (EMG) signals were recorded from the infraspinatus, pectoralis major, serratus anterior, and middle trapezius. Values were compared among muscle groups, among individual muscles at different intensity levels, and among individual muscles at different points in the arc of motion. RESULTS: For submaximal glenohumeral internal rotation, activity in the scapular stabilizers was not different (P = .1-.83) from activity in the internal rotator throughout the range of motion. For the initial two-thirds of maximal internal rotation, middle trapezius activity and pectoralis major activity were higher (P < .05) than serratus anterior activity. For submaximal external rotation, activity in the scapular stabilizers during the middle phase of the motion was higher (P < .05) than activity in the external rotators. For maximal external rotation these differences were present throughout the motion with middle trapezius activity exceeding 100% maximal voluntary contraction. CONCLUSIONS: The scapular stabilizers functioned at a similar or higher intensity than the glenohumeral rotators during internal and external rotation. This highlights the importance of training the scapular stabilizers in upper extremity athletes and in patients with shoulder pathology.

The effect of rotator cuff tears on surgical outcomes after type II superior labrum anterior posterior tears in patients younger than 50 years.

BACKGROUND: Rotator cuff injury in the setting of type II superior labrum anterior posterior lesions is a common finding. Although predictable surgical outcomes can be expected after type II superior labrum anterior posterior repair, the effect of rotator cuff tears on surgical outcome is unknown. HYPOTHESIS: Rotator cuff tears will not negatively affect surgical outcome of type II superior labrum anterior posterior repairs. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: The study group included 93 patients younger than 50 years who underwent arthroscopic type II superior labrum anterior posterior repair and were available for review at a minimum of 2 years after surgery. Group 1 patients were identified as having normal rotator cuffs at the time of repair. Group 2 patients were identified as having rotator cuff injury at the time of repair (either partial-thickness or full-thickness tears). Statistical analysis was performed comparing the postoperative University of California, Los Angeles shoulder scores and overall improvement in University of California, Los Angeles score using the Student t test for significance. RESULTS: Mean follow-up was 2.54 years; 52.7% of patients had evidence of rotator cuff tears at the time of surgery. The mean postoperative University of California, Los Angeles score for group 1 was 32.9 (improvement of 11.0), and the mean postoperative University of California, Los Angeles score for group 2 was 33.3 (improvement of 12.2). There was not a significant difference in any of the outcome measures between groups. CONCLUSION: Predictable short-term surgical results and return to activity can be expected after repair of type II superior labrum anterior posterior lesions in patients younger than 50 years who have coexistent rotator cuff tear. Although cuff lesions did not have a negative effect on the short-term outcome in patients with type II superior labrum anterior posterior lesions, longer-term follow-up is needed to determine natural history of this pathologic condition.

Femoral component positioning in resurfacing arthroplasty--effects on cortical strains.

Previous studies have suggested that femoral component positioning in resurfacing arthroplasty may affect strains in the femoral neck that could lead to decreased implant longevity. A strain gaged, Sawbones model was used to determine the femoral neck strains for a variety of resurfacing head translations and angulations. We found that head positions affected strain distributions, most positions leading to increased neck strains, often over 100%, with the exception being a varus head position where the superior neck strains decreased over 50%. Although the clinical meaning of these findings is unclear, it could be of concern for stress-shielding or fatigue fracture of the femoral neck.

A new surgical technique for arthroscopic repair of the meniscus root tear.

Injury of the meniscal root can lead to meniscal extrusion and loss of normal hoop stress distribution by the meniscus. This has been shown to result in an excessive tibiofemoral contact pressures and has been associated with development of arthritis in the affected compartment of the knee. Repair of meniscal root avulsion has been shown to restore the normal contact stresses, and several techniques for such repair have been described. We report an all-arthroscopic technique that allows anatomic reattachment of the avulsed meniscal root, applicable to both the medial or lateral menisci. Our technique utilizes a novel retrograde reaming device to create a small intraosseous socket at the meniscal tibial attachment, and may be particularly useful for repairing meniscal root avulsions in knees with multiligamentous injuries.

The effect of scapular-retractor fatigue on external and internal rotation in patients with internal impingement.

CONTEXT: Scapular strengthening is thought to be an important component of the rehabilitation of patients with internal impingement. OBJECTIVE: To determine the effect of scapular-retractor-muscle fatigue on internal- and external-rotation-torque production in patients with internal impingement. DESIGN: Case control study. SETTING: Outpatient clinic. PARTICIPANTS: 15 patients and 18 healthy subjects. INTERVENTION: A scapular-retractor-fatigue protocol. MAIN OUTCOME MEASURE: Shoulder-rotation-torque production. RESULTS: After the scapular-retractor-fatigue protocol external-rotation strength was reduced in patients (involved 25%, noninvolved 19%; P < .001). CONCLUSION: Fatigue in the scapular retractors resulted in lower shoulder-rotation-torque production. These findings emphasize the importance of the scapular retractors for proper function of the shoulder rotators with the arm in an abducted position in patients with internal impingement.

Surface replacement arthroplasty of the hip.

Treatment of the young patient with degenerative disease of the hip has historically been a difficult problem for the orthopaedist. Total hip arthroplasty in the young patient has generally produced inferior results as compared to older patients. Surface replacement arthroplasty (SRA) was initially developed over 50 years ago to treat degenerative disease of the hip. It has regained enthusiasm over the last 10 to 15 years as an alternative to total hip arthroplasty for the treatment of degenerative disease of the hip in younger patients. The modern metal-on-metal bearing provides improved wear characteristics over its metal-on-polyethylene predecessor. Multiple studies have demonstrated mid-term results of metal-on-metal SRA, which are comparable to total hip arthroplasty. The long-term survival data of SRA remains to be seen, as does the long-term effect of elevated serum ion levels.

Acetabular fracture through the triradiate cartilage after low-energy trauma.

Although rare, injury to the triradiate cartilage is both a diagnostic and therapeutic challenge. Trauma to the triradiate cartilage or its blood supply can adversely affect acetabular development due to premature physeal closure. A shallow acetabulum with a lateralized hip joint that is prone to subluxation, premature degenerative changes, chronic pain, and functional limitations can result. We present a case of an acetabular fracture with injury to the triradiate cartilage after low-energy trauma in an adolescent male treated nonoperatively and healed without complications.

ACL injuries in the skeletally immature patient.

Anterior cruciate ligament injuries in the pediatric and adolescent population are becoming more common with the trends of increased participation in competitive athletics in younger children. The natural history of this injury is similar to that of the adult and results in frequent reinjury, instability, and debilitation. Delayed reconstruction has proven to be a clinically effective treatment method but requires a prolonged restriction of competitive athletics. Reconstruction in the acute and subacute period has been shown by many authors to be a successful, reproducible treatment regimen. Nonetheless, the unique pitfalls of ACL reconstruction in a skeletally immature patient must not be overlooked. A thorough preoperative evaluation for leg-length discrepancy or subtle angular deformity is essential to identify the presence of an entity that might otherwise be attributed to surgical complication. For the patient nearing skeletal maturity with little growth remaining, we recommend the standard tunnel positioning and the use of soft-tissue graft. For younger patients who have significant growth remaining, alternative physeal "safe" procedures should be considered. No prospective, randomized studies compare the clinical success of graft type, graft placement, or graft fixation in this age group. Further follow-up of existing study groups and prospective research is warranted to fine-tune the result-based decision making for treatment of this injury.

Renal osteodystrophy.

The incidence of chronic renal disease is increasing, and the pattern of renal osteodystrophy seems to be shifting from the classic hyperparathyroid presentation to one of low bone turnover. Patients with persistent disease also live longer than previously and are more physically active. Thus, patients may experience trauma as a direct result of increased physical activity in a setting of weakened pathologic bone. Patient quality of life is primarily limited by musculoskeletal problems, such as bone pain, muscle weakness, growth retardation, and skeletal deformity. Chronic renal disease also increases the risk of comorbidity, such as infection, bleeding, and anesthesia-related problems. Current treatment strategies include dietary changes, plate-and-screw fixation, and open reduction and internal fixation.

Osteochondral lesions of the talus.

Osteochondral lesions of the talus occur infrequently and usually represent late sequelae of ankle trauma. Because of the functional significance of the talus and its limited capacity for repair, correct early diagnosis is important. Osteochondral fractures should be suspected in patients with chronic ankle pain, especially those with a prior ankle injury. Historically, plain radiographs have been used to stage lesions; more recently, magnetic resonance imaging and arthroscopy have been used. Non-surgical management remains the mainstay of treatment of acute, nondisplaced osteochondral lesions. Surgical management is reserved for unstable fragments or failure of nonsurgical treatment. Recent advances in osteochondral grafting have allowed reconstruction of the talar dome, leading to more predictable relief of pain and improvement of function.

Occult bilateral acetabular fractures associated with high-energy trauma and osteoporosis.

Acetabular fractures that are radiographically occult are associated with osteoporosis, low-energy trauma, and advanced age. We present a case of bilateral occult acetabular fractures in a 65-year-old woman who presented with an open tibia-fibula fracture and compartment syndrome and thoracolumbar spine fractures sustained in a motor vehicle accident. Initial radiographs of the pelvis and a pelvic CT scan did not show any bony injuries when the films were reviewed prospectively. At 6 weeks after injury, a CT scan and plain radiographs showed bilateral healing transverse acetabular fractures with acetabular protrusio on the left. At most recent follow-up, the patient had posttraumatic hip arthritis with moderate protrusio on the left and was ambulating with a cane. Total hip arthroplasty is anticipated in the future.