Kevin P. Speer

Acute Dislocation of the Patella A Correlative Pathoanatomic Study

The objective of our study was to elucidate the char acteristic pathoanatomy associated with patellar dislo cation and report the preliminary results of early surgi cal repair. Twenty-three patients with documented patellar dislocation had standard radiographs and a magnetic resonance imaging scan. Intraarticular le sions were evaluated and treated arthroscopically fol lowed by an open exploration of the medial aspect of the knee in 16 patients. Twelve patients were observed for a minimum of 2 years after surgical repair (average, 34 months). Eleven patients returned for a follow-up examination. Magnetic resonance imaging revealed ef fusion (100%), tears of the femoral insertion of the medial patellofemoral ligament (87%), increased signal in the vastus medialis muscle (78%), and lateral fem oral condyle (87%) and medial patellar (30%) bone bruises. Arthroscopic examination revealed osteo chondral lesions involving the patella and the lateral femoral condyle in 68% of cases. Open surgical explo ration revealed tears of the medial patellofemoral liga ment off the femur in 15 of 16 patients (94%). After medial patellofemoral ligament repair, none of the pa tients experienced recurrent dislocation. Overall 58% of the results were considered to be good or excellent and 42% were fair. Fifty-eight percent of the group returned to their previous sport with no or minor limitations.

Biomechanical evaluation of a simulated Bankart lesion.

The purpose of this study was to determine the effect of sectioning of the anterior part of the inferior glenohumeral ligament (a simulated Bankart lesion) on load-induced multidirectional glenohumeral motion. Nine fresh, intact cadaveric shoulders were tested on a special apparatus that constrained three rotations but allowed simultaneous measurement of anterior-posterior, superior-inferior, and medial-lateral translation. Coupled anterior-posterior and superior-posterior translations were recorded while anterior, posterior, superior, and inferior forces of fifty newtons were applied sequentially. Testing was done in three positions of humeral elevation in the scapular plane, in three positions of humeral rotation, and with an externally applied joint-compression load of twenty-two newtons. A liquid-metal strain-gauge was placed on the posterior band of the inferior glenohumeral ligament to assess concomitant posterior capsular strain during the various test conditions. All shoulders were tested intact and again after the inferior glenohumeral ligament and the labrum had been detached from the glenoid from just superior to the anterior band of the inferior glenohumeral ligament to a point just posterior to the infraglenoid tubercle. The simulated Bankart lesion resulted in selected increases in anterior translation at all positions of elevation, in posterior translation at 90 degrees of elevation, and in inferior translation at all positions of elevation. However, these increases were very small; the maximum mean increase in translation seen over-all was only 3.4 millimeters, which occurred during inferior translation at 45 degrees of elevation.(ABSTRACT TRUNCATED AT 250 WORDS)

Retroversion of the Humerus in the Throwing Shoulder of College Baseball Pitchers

Background Increased external rotation and decreased internal rotation have been noted to occur progressively in the throwing shoulder of baseball pitchers. Hypothesis Proximal remodeling of the humerus contributes to the rotational asymmetry between shoulders in pitchers. Study Design Descriptive anatomic study. Methods Both shoulders of 19 male college baseball pitchers were evaluated and retroversion of the humerus calculated by using the technique of Söderlund et al. Measurements were taken of passive glenohumeral external rotation at 0° and 90° of abduction and internal rotation at 90° of abduction under a 3.5-kg load. Subjects completed a questionnaire on the amount and duration of overhead throwing performed during the ages 8 through 16 years. Results All of the subjects had greater external rotation at 0° and 90° of abduction, decreased internal rotation at 90° of abduction, and greater retroversion of the humerus in their dominant compared with nondominant shoulders. A significant difference was found between dominant and nondominant external rotation at 0° and 90° of abduction, internal rotation at 90° of abduction, and retroversion of the humerus. In the dominant arm, there was a significant correlation between retroversion of the humerus and external rotation at 0° and 90° of abduction. There was also a significant correlation between the side-to-side difference in retroversion of the humerus compared with the side-to-side difference in external rotation at 90° of abduction. Conclusions Rotational changes in the throwing shoulder are due to bony as well as soft tissue adaptations.

Interscalene brachial plexus block with a continuous catheter insertion system and a disposable infusion pump.

Continuous interscalene brachial plexus blockade traditionally requires a hospital stay for local anesthetic infusion, and achieving consistent catheter insertion may be difficult. Incorporating long-acting pain relief from a continuous peripheral nerve block, with a reliable method of catheter insertion, and a self-contained infusion system would be a valuable asset for short-stay care. We compared the efficacy of single injection interscalene brachial plexus blockade to a continuous peripheral nerve block, with an insulated Tuohy system and a disposable infusion pump. Forty adult patients scheduled for open rotator cuff repair were entered in this randomized, double-blinded, placebo-controlled study. Patients received an interscalene brachial plexus blockade and a continuous peripheral nerve catheter as their primary anesthetic and then, were assigned to receive one of two different postoperative infusions: either 0.2% ropivacaine at 10 mL/h via a disposable infusion pump or normal saline at 10 mL/h via a disposable infusion pump (n = 18–20 per group). Visual analog pain scores and postoperative morphine consumption were measured for 24 h. The ropivacaine group showed less pain than the placebo group (P = 0.0001) between 12 and 24 h after the initial injection of local anesthetic. In addition, initial interscalene blockade was successful in all patients and all redosed catheters were functional after 24 h with the continuous catheter insertion system. We conclude that it is possible to achieve a high rate of successful catheter placement and analgesia by using the continuous catheter insertion system and a disposable infusion pump in the ambulatory setting. This method of analgesia may offer improved pain relief after outpatient rotator cuff repair. Implications This study demonstrates that it is possible to achieve successful interscalene brachial plexus continuous catheter insertion and a high degree of persistent analgesia by using a catheter insertion system and a disposable infusion pump administering 0.2% ropivacaine.

The Manual Muscle Examination for Rotator Cuff Strength An Electromyographic Investigation

The electromyographic activity of eight muscles of the rotator cuff and shoulder girdle (supraspinatus, in fraspinatus, subscapularis, pectoralis, latissimus dorsi, and the anterior, middle, and posterior deltoid) was measured from the nondominant shoulders of 11 sub jects during a series of 29 isometric contractions. The contractions simulated different positions used for strength testing of the rotator cuff and involved eleva tion, external rotation, and internal rotation at three degrees of initial humeral rotation (-45° of internal rotation, 0°, +45° of external rotation) and scapular elevation (0°, 45°, 90°). Isolation of the supraspinatus muscle was best achieved with the test position of elevation at 90° of scapular elevation and +45° (exter nal rotation) of humeral rotation. Isolation of the in fraspinatus muscle was best achieved with external rotation at 0° of scapular elevation and -45° (internal rotation) of humeral rotation. Isolation of the subscap ularis muscle was best achieved with the Gerber push- off test. This study used four criteria for identifying the optimal manual muscle test for each rotator cuff mus cle : 1) maximal activation of the cuff muscle, 2) minimal contribution from involved shoulder synergists, 3) min imal provocation of pain, and 4) good test-retest reli ability. Based on the results of this study and known painful arcs of motion, an objective identification of the optimal tests for the manual muscle testing of the cuff was elucidated.

Osseous injury associated with acute tears of the anterior cruciate ligament

Multiplanar spin-echo magnetic resonance imaging was performed on 54 patients with acute complete anterior cruciate ligament tears. Imaging was done within 45 days of index anterior cruciate ligament injury. Spin- echo T1- and T2-weighted images were used to deter mine the lesion morphology and location. Only the T2- weighted sagittal images were used for the incidence assessment; T2-weighted spin-echo imaging reflects free water shifts and best indicates the acute edema and inflammatory changes from injury. Eighty-three percent (45 of 54) of the knees had an osseous contusion directly over the lateral femoral con dyle terminal sulcus. The lesion was highly variable in size and imaging intensity; however, the most intense signal was always contiguous with the subchondral plate. Posterolateral joint injury was seen in 96% (43 of 45) of the knees that had a terminal sulcus osseous lesion determined by magnetic resonance imaging. This posterolateral lesion involves a spectrum of injury, in cluding both soft tissue (popliteus-arcuate capsuloliga mentous complex) and hard tissue (posterolateral tibial plateau) injuries. The consistent location of the osseous and soft tissue injuries underscores a necessary similar mechanism of injury associated with these acute anterior cruciate ligament tears. Based on these characteristic findings, several proposed mechanisms of injury are discussed.

An Arthroscopic Technique for Anterior Stabilization of the Shoulder with a Bioabsorbable Tack

Arthroscopically assisted repair of the anterior aspect of the labrum with use of a bioabsorbable tack was performed in fifty-two consecutive patients who had chronic anterior instability of the shoulder. The average age of the patients was twenty-eight years (range, sixteen to fifty years). The etiology of the instability was a traumatic injury in forty-nine patients; twenty-six of those injuries were sustained during participation in a contact sport. Fifty shoulders had a Bankart lesion. The patients were evaluated at an average of forty-two months (range, twenty-four to sixty months) after the procedure. Forty-one (79 per cent) of the patients were asymptomatic and were able to participate in sports without restriction. The repair was considered to have failed in eleven (21 per cent) of the patients. In four of them, the failure resulted from a single traumatic reinjury during participation in a contact sport, and three of these reinjuries were treated nonoperatively. The remaining seven failures occurred atraumatically. Eight patients had an open glenoid-based capsulorrhaphy as a consequence of recurrent instability. At the reoperation, no evidence of the tack was found in any patient. In seven patients, the Bankart lesion had completely healed, and the anteroinferior aspect of the capsule was patulous. Anterior stabilization of the shoulder with a bioabsorbable tack may be indicated for patients who have anterior instability but do not need a capsulorrhaphy or capsular imbrication to reduce the joint volume.

Radiographic imaging of muscle strain injury

We reviewed our experience with computed tomogra phy and magnetic resonance imaging of acute muscle strain injury. We imaged 50 athletes (average age, 28 years; range, 17 to 42) who had an acute muscle strain involving either the adductor, hamstring, quadriceps, or triceps surae muscles. Computed tomography (axial imaging) was used from 1982 to 1987 for 27 athletes. Spin-echo magnetic resonance imaging (axial, coronal, sagittal imaging) was used from 1987 to 1991 for 23 athletes. Computed tomography and magnetic resonance im aging localize the strain injury to a single muscle within a group of synergists; the adductor longus, rectus femoris, and medial head of gastrocnemius muscles are most prone to strain injury. A disruption occurs predictably at the myotendinous junction; fluid collects at the disruption site and dissects along the epimysium and subcutis. Muscle tissue remote from the myoten dinous junction clearly demonstrates extensive injury with abundant magnetic resonance imaging signal changes consistent with edema and inflammation. Fol low-up computed tomographic and magnetic reso nance imaging studies can clearly demonstrate atrophy, fibrosis, and calcium deposition.

A comparison of 0.5% bupivacaine, 0.5% ropivacaine, and 0.75% ropivacaine for interscalene brachial plexus block

The onset time and duration of action of ropivacaine during an interscalene block are not known.The potentially improved safety profile of ropivacaine may allow the use of higher concentrations to try and speed onset time. We compared bupivacaine and ropivacaine to determine the optimal long-acting local anesthetic and concentration for interscalene brachial plexus block. Seventy-five adult patients scheduled for outpatient shoulder surgery under interscalene block were entered into this double-blind, randomized study. Patients were assigned (n = 25 per group) to receive an interscalene block using 30 mL of 0.5% bupivacaine, 0.5% ropivacaine, or 0.75% ropivacaine. All solutions contained fresh epinephrine in a 1:400,000 concentration. At 1-min intervals after local anesthetic injection, patients were assessed to determine loss of shoulder abduction and loss of pinprick in the C5-6 dermatomes. Before discharge, patients were asked to document the time of first oral narcotic use, when incisional discomfort began, and when full sensation returned to the shoulder. The mean onset time of both motor and sensory blockade was <6 min in all groups. Duration of sensory blockade was similar in all groups as defined by the three recovery measures. We conclude that there is no clinically important difference in times to onset and recovery of interscalene block for bupivacaine 0.5%, ropivacaine 0.5%, and ropivacaine 0.75% when injected in equal volumes. Implications: In this study, we demonstrated a similar efficacy between equal concentrations of ropivacaine and bupivacaine. In addition, increasing the concentration of ropivacaine from 0.5% to 0.75% fails to improve the onset or duration of interscalene brachial plexus block. (Anesth Analg 1998;87:1316-9)

An Evaluation of the Shoulder Relocation Test

The purpose of this study was to evaluate the sensitivity, specificity, negative and positive predictive values, and accuracy of the shoulder relocation test in 100 patients who underwent shoulder surgery. Based on operative data and examination under anesthesia, the diagnoses were grouped into six categories: anterior instability (without cuff disease), posterior instability, rotator cuff disease (without associated anterior instability), acro mioclavicular disorder, osteoarthrosis, and instability of the biceps tendon. The test was performed on the day of surgery by placing the arm in a position of 90° of humerothoracic abduction and 90° of external rotation (90°/90°). Patient responses of pain and apprehension (considered separately) were assessed in this position both with and without application of an anterior force to the proximal humerus. The relocation test assessed diminution of pain and apprehension after application of a posteriorly directed force to the proximal humerus relative to the position of 90°/90° alone and to the po sition of an anterior force being applied to the proximal humerus. Overall, 63 patients reported pain with 90°/90°; 74 reported pain when an anterior force to the proximal humerus was applied: the anterior instability group alone had 46 and 63 reports of pain, respectively; the rotator cuff group alone had 82 and 88 reports of pain, respectively. The only positive responses for apprehen sion were in the anterior instability group, of which 63% had apprehension with 90°/90° alone and 74 had ap prehension when an anterior humeral force was ap plied. The overall accuracy of the shoulder relocation test was <50% when the response of pain alone was considered and >80% when the response of apprehen sion alone was considered. The performance of the test was contrasted within the anterior instability and rotator cuff disease groups. A positive relocation test for pain was observed in 30% (14 of 46) of the anterior instability group and in 44% (15 of 34) of the rotator cuff disease group; this increased to 54% (25 of 46) and 56% (19 of 34), respectively, with reference to the position of an anterior force on the proximal humerus.