Scott D. Mair

The role of fatigue in susceptibility to acute muscle strain injury.

We investigated the role of fatigue in muscle strain injuries using the extensor digitorum longus muscles of 48 rabbits. The muscles of the rabbits were fatigued by 25% or 50% then stretched to failure and compared with the contralateral controls. Three rates of stretch were used. The force to muscle failure was reduced in the fatigued leg in all groups (range, 93% to 97.4% compared with the controls). The change in muscle length in the fatigue groups was not different from the controls. The amount of energy absorbed in the fa tigued muscle was 69.7% to 92% that of the energy absorbed in the control muscle. The lowest energy absorption occurred in muscles that were more fa tigued. In eight additional rabbits, fatigued extensor digitorum longus muscles were compared with sub- maximally stimulated muscles with the equivalent con tractile properties, and no difference was seen. Mus cles subjected to strains are frequently injured under high-intensity eccentric loading conditions. Under these conditions, muscles absorb energy and provide control and regulation of limb movement. Our data showed that muscles are injured at the same length, regardless of the effects of fatigue. However, fatigued muscles are able to absorb less energy before reach ing the degree of stretch that causes injuries.

Triceps Tendon Ruptures in Professional Football Players

Background Distal rupture of the triceps tendon is a rare injury, and treatment guidelines are not well established. Hypothesis Football players with triceps tendon ruptures will be able to return to their sport with minimal functional deficits. Study Design Uncontrolled retrospective review. Methods Twenty-one partial and complete ruptures of the triceps tendon were identified in 19 National Football League players over a period of 6 years. Team physicians retrospectively reviewed training room, clinical, and operative notes for each of these players. Results Most of the injured players were linemen. The most common mechanism of injury was an eccentric load to a contracting triceps. Seven players had prodromal symptoms prior to injury, and 5 had received a cortisone injection. Eleven elbows with complete tears underwent surgical repair. Of 10 players with partial tears, 6 healed without surgery. One player suffered a subsequent complete tear requiring surgery, and 3 with residual pain and weakness underwent surgical repair following the season. Two surgical complications occurred, both requiring a second operation. All of the players but 1 returned to play at least one season of professional football after their injury. Conclusions Partial triceps tendon ruptures can heal without functional deficit. Surgical repair for complete ruptures generally produces good functional results and allows return to play.

Posterior Labral Injury in Contact Athletes

Nine athletes (seven football offensive linemen, one defensive lineman, and one lacrosse player) were found at arthroscopy to have posterior labral detachment from the glenoid. In our series, this lesion is specific to contact athletes who engage their opponents with arms in front of the body. All patients had pain with bench pressing and while participating in their sport, diminishing their ability to play effectively. Conservative measures were ineffective in relieving their symptoms. Examination under anesthesia revealed symmetric glenohumeral translation bilaterally, without evidence of posterior instability. Treatment consisted of glenoid rim abradement and posterior labral repair with a bioabsorbable tack. All patients returned to complete at least one full season of contact sports and weightlifting without pain (minimum follow-up, 2 years). Although many injuries leading to subluxation of the glenohumeral joint occur when an unanticipated force is applied, contact athletes ready their shoulder muscles in anticipation of impact with opponents. This leads to a compressive force at the glenohumeral joint. We hypothesize that, in combination with a posteriorly directed force at impact, the resultant vector is a shearing force to the posterior labrum and articular surface. Repeated exposure leads to posterior labral detachment without capsular injury. Posterior labral reattachment provides consistently good results, allowing the athlete to return to competition.

Incidence and Location of bone Bruises after Acute Posterior Cruciate Ligament Injury

Background In patients suffering from an anterior cruciate ligament injury, the incidence and location of bone bruises are well documented. This study reports data regarding bone bruises after acute posterior cruciate ligament injury. Hypothesis Bone bruises associated with posterior cruciate ligament injury are common, and their location differs from those seen with anterior cruciate ligament injury. Study Design Retrospective cohort study. Methods Thirty-five consecutive patients were identified as having a grade II or III posterior cruciate ligament tear, with an intact anterior cruciate ligament, in which a magnetic resonance imaging scan had been obtained within 20 days of injury. Magnetic resonance imaging scans were reviewed to document bone bruises, associated medial or lateral ligamentous injury, and meniscal and chondral abnormalities. Results Of the 35 patients, 29 (83%) had a bone bruise in at least one location. Bone bruises were found throughout the joint, more widely dispersed than is commonly seen with anterior cruciate ligament injury. Also, 29 patients had magnetic resonance imaging findings of associated ligamentous injury. Lateral bone bruises were associated with medial collateral ligament injury, whereas medial bone bruises correlated with posterolateral injury. Conclusions The incidence of bone bruises associated with posterior cruciate ligament injury is similar to that seen with anterior cruciate ligament injury. Their location is more widely dispersed. The location of a bone bruise should lead to careful magnetic resonance imaging inspection and physical examination for ligamentous injury to the opposite side of the joint. Truly isolated posterior cruciate ligament injuries are rare, as most occur with osseous and some degree of associated ligamentous injury.

Rotator Cuff Tear

Tendinopathy of the long head of the biceps is a common cause of anterior shoulder pain. As such, the anatomy and function of the tendon as well as its pathophysiology and different treatment methods have been studied extensively. The pathophysiology is a spectrum beginning with inflammation and leading to tendon degeneration. Different clinical tests and imaging modalities may all be employed to help aid in diagnosis. Conservative management is the first-line treatment, but surgical intervention may be warranted. In general, tenotomy or tenodesis is performed depending, among other things, on the age and activity level of the patient. There are several different methods for tenodesis, each with certain advantages and disadvantages. Patient factors must be considered when choosing the optimal treatment.

Plantar fibromatosis: treatment of primary and recurrent lesions and factors associated with recurrence.

Plantar fibromatosis is a benign but often problematic foot disorder which, when surgically treated, is difficult to eradicate. The purpose of this investigation was to identify epidemiologic factors associated with disease recurrence and to determine which method of treatment most successfully eliminated recurrence. A retrospective review of surgical pathology reports and clinical histories from 1979 to 1993 was performed to identify all patients who underwent surgery for plantar fibromatosis at our institution during that time. Thirty-three feet of 30 patients were identified with a minimum 2-year follow-up. Seventeen feet underwent surgery for primary lesions, and 4 of 10 that had local excision, 1 of 3 that had wide excision, and 2 of 4 that had subtotal fasciectomy (with or without skin grafting) had recurrence. All 16 feet in patients presenting with recurrent lesions had undergone prior local excision at other institutions. When combined with patients from our institution who underwent a second procedure, 21 feet had surgery for recurrent plantar fibromatosis. Of these, three of four had further recurrence when treated with local or wide excision. In feet with recurrences treated with subtotal fasciectomy, only 4 of 17 had recurrence after the first attempt at such treatment. Average follow-up for all patients was 7.7 years, and all patients with postoperative recurrences showed evidence of disease within 14 months after surgery (mean, 6.9 months). Factors identified with an increased risk for recurrence were multiple nodules, bilateral lesions, and positive family history. In treating recurrent disease, subtotal fasciectomy was more effective than local or wide excision. This study identified factors associated with a significant likelihood of postoperative recurrence in treating plantar fibromatosis and found subtotal fasciectomy to provide the most successful treatment in eradicating disease in recurrent cases.

Evaluation of Uncemented Total Hip Arthroplasty in Patients With Avascular Necrosis of the Femoral Head

Thirty-seven uncemented primary porous coated anatomic (PCA) total hip arthroplasties (THA) that were performed in 33 patients for the diagnosis of avascular necrosis (AVN) between June 1984 and December 1986 were reexamined at four- to six-year follow-up periods. Final clinical evaluation showed an 86-point average Harris hip rating (range, 47-100 points), which had improved from an average preoperative rating of 42 points (range, 20-61 points). Thigh pain, which was usually not functionally limiting, occurred in 11 patients (25%), and seven patients (16%) had a moderate or severe limp. Nine patients (20%) required the use of a cane. Long-term radiographic evaluation in 37 hips demonstrated acetabular cup migration in one hip, acetabular lucencies in four hips (11%), and acetabular bead loosening in ten hips (27%). Femoral subsidence occurred in five hips (14%) and femoral bead loosening in 11 hips (30%). Thirty hips (81%) demonstrated radiographic evidence of stable bony ingrowth. No revisions were performed for aseptic loosening, but two prostheses were removed for infection. These results of uncemented THA in patients with AVN appear to be as good or better than the results reported for cemented arthroplasty in AVN at this interval of a follow-up period. This study supports the use of uncemented devices, especially with the newer designs and increasing surgical experience in this difficult patient population.

Shoulder Instability With Absence of the Long Head of the Biceps Tendon

We present a case of a 25-year-old woman undergoing arthroscopy for multidirectional instability. She was found to have a complete absence of the long head of the biceps tendon, thought to be congenital. It is hypothesized that the absence of the biceps may have played a role in the instability.

Rupture of a bifurcated distal biceps tendon: A case report

Typically, the biceps brachii originates proximally with two heads from the scapula that unite to form a common tendon that inserts into the radial tuberosity, with the bicipital aponeurosis inserting onto the ulna. Multiple anatomic anomalies of the biceps brachii muscle have been identified1-4. These variations are far more common at the muscular origin than at the insertion, with the muscle occasionally having accessory heads at its origin1,2,4. Much less commonly, anomalous insertions of the biceps have been described; these variations have included slips extending to the medial intermuscular septum, the medial epicondyle, the pronator teres, or the extensor carpi radialis brevis3,5. We are aware of only a single case report that has described the clinical relevance of these anomalies6, and their importance is unclear. Distal biceps rupture is a relatively rare injury that is much less frequent than proximal tendon rupture. The etiology of distal biceps rupture is unclear. However, it may involve some degeneration of the tendon at its insertion on the radial tuberosity. Partial ruptures of the distal biceps tendon are quite rare relative to complete tears and may be difficult to diagnose7-9. A recent report documented excellent outcomes for eight patients in whom a partial tear had been repaired through a single posterior incision10. We report the case of a patient who had a rupture of a bifurcated distal biceps tendon with separate musculotendinous junctions, findings that were consistent with an unfused biceps brachii muscle. The patient was informed that information concerning this case would be submitted for publication. We are aware of no previous reports of this anomaly. Athirty-nine-year-old, right-hand-dominant man who worked as a law-enforcement officer injured the right arm while lifting …

Electromyographical Comparison of Four Common Shoulder Exercises in Unstable and Stable Shoulders

This study examines if electromyographic (EMG) amplitude differences exist between patients with shoulder instability and healthy controls performing scaption, prone horizontal abduction, prone external rotation, and push-up plus shoulder rehabilitation exercises. Thirty nine subjects were categorized by a single orthopedic surgeon as having multidirectional instability (n = 10), anterior instability (n = 9), generalized laxity (n = 10), or a healthy shoulder (n = 10). Indwelling and surface electrodes were utilized to measure EMG activity (reported as a % of maximum voluntary isometric contraction (MVIC)) in various shoulder muscles during 4 common shoulder exercises. The exercises studied effectively activated the primary musculature targeted in each exercise equally among all groups. The serratus anterior generated high activity (50–80% MVIC) during a push-up plus, while the infraspinatus and teres major generated moderate-to-high activity (30–80% MVIC) during both the prone horizontal and prone external rotation exercises. Scaption exercise generated moderate activity (20–50% MVIC) in both rotator cuff and scapular musculature. Clinicians should feel confident in prescribing these shoulder-strengthening exercises in patients with shoulder instability as the activation levels are comparable to previous findings regarding EMG amplitudes and should improve the dynamic stabilization capability of both rotator cuff and scapular muscles using exercises designed to address glenohumeral joint instability.