Ronald S. Kvitne

Biomechanical comparison of a single-row versus double-row suture anchor technique for rotator cuff repair

Background Reestablishment of the native footprint during rotator cuff repair has been suggested as an important criterion for optimizing healing potential and fixation strength. Hypothesis A double-row rotator cuff footprint repair will demonstrate superior biomechanical properties compared with a single-row repair. Study Design Controlled laboratory study. Methods In 9 matched pairs of fresh-frozen cadaveric shoulders, the supraspinatus tendon from 1 shoulder was repaired with a double-row suture anchor technique: 2 medial anchors with horizontal mattress sutures and 2 lateral anchors with simple sutures. The tendon from the contralateral shoulder was repaired using a single lateral row of 2 anchors with simple sutures. Each specimen underwent cyclic loading from 10 to 180 N for 200 cycles, followed by tensile testing to failure. Gap formation and strain over the footprint area were measured using a video digitizing system; stiffness and failure load were determined from testing machine data. Results Gap formation for the double-row repair was significantly smaller (P< .05) when compared with the single-row repair for the first cycle (1.67 ± 0.75 mm vs 3.10 ± 1.67 mm, respectively) and the last cycle (3.58 ± 2.59 mm vs 7.64 ± 3.74 mm, respectively). The initial strain over the footprint area for the double-row repair was nearly one third (P< .05) the strain of the single-row repair. Adding a medial row of anchors increased the stiffness of the repair by 46% and the ultimate failure load by 48% (P< .05). Conclusion Footprint reconstruction of the rotator cuff using a double-row repair improved initial strength and stiffness and decreased gap formation and strain over the footprint when compared with a single-row repair. Clinical Relevance To achieve maximal initial fixation strength and minimal gap formation for rotator cuff repair, reconstructing the footprint attachment with 2 rows of suture anchors should be considered.

A new technique: in vitro suture anchor fixation has superior yield strength to bone tunnel fixation for distal biceps tendon repair.

Background Suture anchor and bone tunnel fixations are used for distal biceps tendon repairs and have not been compared. Hypothesis Suture anchor fixation is equal or superior to bone tunnel fixation. Study Design Randomized controlled in vitro study. Methods A new fixation technique was compared to traditional bone tunnel fixation of distal biceps tendon ruptures between randomly selected sides of nine matched-pair, fresh-frozen elbow specimens from cadaveric donors (mean age = 74.7 years). Bone densities were determined. The distal biceps tendon was attached to the actuator of a servohydraulic load frame and loaded to tensile failure at a constant rate of 4 mm/sec. Bone density, sex, age, side, tuberosity area, repair, failure type, repair stiffness, and yield strength were compared. Results Superior yield strength of suture anchor fixation (263 N) compared to bone tunnel fixation (203 N) (P= 0.0233) were demonstrated. When suture anchor fixation failure (1 of 9) occurred, the matched pair also failed. Conclusion Suture anchor fixation offers an equal if not superior alternative to bone tunnel fixation for repair of the distal biceps tendon in the specimens tested. Clinical Relevance Suture anchor fixation may be used for distal biceps tendon repairs.

Anterior capsulolabral reconstruction of the shoulder in athletes in overhand sports

From April 1, 1985, through June 30, 1987, 25 skilled athletes with shoulder pain secondary to anterior gle nohumeral instability that had failed to improve with conservative therapy had an anterior capsulolabral re construction. All but one athlete completed a formal rehabilitation program with an average followup of 39 months. The results at followup were rated excellent in 68%, good in 24%, fair in 4%, and poor in 4%. Seven teen patients returned to their prior competitive level for at least 1 year. This operation and rehabilitation program may allow many athletes who participate in overhand activities or throwing sports to return to their prior level of competition.

The diagnosis and treatment of anterior instability in the throwing athlete.

In the overhand or throwing athlete, the shoulder is extremely vulnerable to injury due to the repetitive, high-energy forces. When these stresses are applied at a rate that exceeds that of tissue repair, progressive damage to the shoulders stabilizing structures can occur. With continued throwing, the static restraints become progressively attenuated, allowing anterior glenohumeral subluxation. Initially, the dynamic stabilizers can compensate for this mild instability with increased muscle activity. Prolonged activity, however, may lead to fatigue. Over time, these compensatory mechanisms can become overloaded. The humeral head then may subluxate anteriorly, where it contacts with the coracoacromial arch, ultimately leading to subacromial impingement. Posterosuperior glenoid impingement may also occur as anterior humeral translation allows the undersurface of the tendinous portions of the supraspinatus and infraspinatus to impinge along the posterosuperior border of the glenoid rim. Fortunately, conservative management is effective in most chronic overuse injuries and includes an initial period of relative rest (avoidance of throwing), oral nonsteroidal antiinflammatory medication, a physical therapy program structured to provide local modalities to reduce inflammation, and a strengthening program for the rotator cuff and scapular rotators. For those athletes with continued symptoms, surgical intervention may become necessary. The appropriate surgical treatment depends on the diagnosis. In the young throwing athlete with shoulder pain, it is essential to recognize that instability or occult subluxation, rather than impingement, is the primary underlying pathology. The anterior capsulolabral reconstruction addresses the problem of instability by correcting the capsular redundancy or labral damage or both. When performed in the manner described, muscle attachments and proprioceptive muscle fibers are not disturbed and full shoulder range of motion can quickly be achieved. This most recent surgical technique and postoperative rehabilitation program has resulted in a significant improvement in the ability to correct instability in those athletes who have failed a prolonged course of conservative care. Prevention of these injuries may be attained, it is hoped, through continued research into the basic biomechanics and the pathoanatomy associated with overhand sports.(ABSTRACT TRUNCATED AT 400 WORDS)

Surgical Repair of Distal Biceps Tendon Ruptures A Biomechanical Comparison of Two Techniques

Background Rupture of the distal biceps brachii tendon has most commonly been repaired by anatomic reattachment of the tendon to the radial tuberosity by a single- or two-incision approach. Researchers have studied suture anchor attachment through a single incision, but the tendon-suture interface and bone quality have not previously been analyzed. Hypothesis Suture anchor repair results in stiffness and tensile strength equal to that of bone-tunnel repair for biceps tendon rupture. Study Design Controlled laboratory study. Methods Twelve matched pairs of fresh-frozen cadaveric elbow specimens were used. Suture anchor and bone-tunnel tendon repairs were performed in a randomized fashion. Each specimen was loaded to tensile failure. Load-displacement graphs were generated to calculate repair stiffness, yield strength, and ultimate strength. Computed tomography bone density measurements and additional statistical analyses were then performed after grouping the specimens by mode of failure. Results The bone-tunnel repair was found to be significantly stiffer in all cases and to have significantly greater tensile strength than the suture anchor repair in the younger, nonosteoporotic elbows. Conclusions Suture anchor repairs were not as stiff or strong as bone-tunnel repairs. Clinical Relevance Biceps tendon surgery using the traditional two-incision technique yields a stronger and stiffer repair in the typical patient with this injury.

Infraspinatus Muscle-splitting Incision in Posterior Shoulder Surgery An Anatomic and Electromyographic Study

Standard posterior shoulder surgical approaches include infraspinatus tendon detachment and infraspinatus-teres minor interval development. Cadav eric and clinical investigation of a new infraspinatus- splitting approach to the posterior glenohumeral joint was undertaken to assess efficacy in providing expo sure, preserving tendon attachment, and avoiding neu rologic compromise. Infraspinatus musculotendinous and neural anatomy was examined in 20 cadavers. Four patients with posterior shoulder instability underwent posterior capsulorrhaphy through this infraspinatus- splitting approach, followed by electrodiagnostic test ing. Infraspinatus muscle was bipennate in all speci mens, the tendinous interval an average 14 mm inferior to the scapular spine at the glenoid rim. The infraspinatus-splitting interval bisected the posterior glenoid rim at its midpoint, whereas the infraspinatus- teres minor interval crossed the glenoid rims lower quarter. The suprascapular nerve provided sole inner vation to the infraspinatus muscle in all specimens, en tering the infraspinous fossa at the notch as a single trunk 22 mm medial to the glenoid rim. Minimum branch ing variability was observed. Electrodiagnostic testing showed no evidence of axonal damage or muscle de nervation in either infraspinatus pennate bundle. Lim iting infraspinatus-splitting dissection medially to 1.5 cm from the posterior glenoid rim prevents damage to any interval-crossing suprascapular nerve branches. Pos terior shoulder surgery through a horizontal, longitudi nal infraspinatus tendon-splitting approach provides ex cellent exposure of posterior capsule, labrum, and glenoid, without requiring tendon detachment or caus ing neurologic compromise.

Biomechanical evaluation of multidirectional glenohumeral instability and repair.

The purpose of the current study was to create a multidirectional glenohumeral instability model and compare anterior capsulolabral reconstruction with inferior capsular shift with respect to their effects on glenohumeral translation and rotational range of motion. Ten fresh frozen cadaveric shoulders were used with a custom shoulder translation testing jig. To create the multidirectional instability model the capsule was stretched an additional 20% from the initial rotational range of motion in apprehension and neutral positions. Shoulders were repaired using anterior capsulolabral reconstruction (n = 5) or an inferior capsular shift (n = 5). Anterior, posterior, inferior, and superior translations were measured along with the rotational range of motion for intact, stretched, and repaired conditions. All specimens showed increased translations and rotations after stretching. Both repair techniques significantly reduced anterior, posterior, and inferior translation. The inferior capsular shift was more effective in reducing inferior translation in the apprehension position; however, postoperative rotational range of motion was restricted significantly when compared with anterior capsulolabral reconstruction, and posterior subluxation of the humeral head was seen in all specimens. These results indicate that a vertical capsulorrhaphy with a medial to lateral shift of the glenohumeral capsule, as in the inferior capsular shift repair, significantly reduces rotational range of motion when compared in vitro with the horizontal shift of the anterior capsulolabral reconstruction.

Electromyography of the quadriceps in patellofemoral pain with patellar subluxation.

This study compared muscle activity and timing of gait phases during functional activities in 13 subjects with patellofemoral pain associated with lateral subluxation and in 11 subjects with healthy knees. Fine wire electromyography recorded activity in the vastus lateralis and vastus medialis oblique during walking and ascending and descending stairs. Subjects were filmed to divide the activities into phases and determine timing. The vastus medialis oblique and vastus lateralis had similar patterns during all activities. Subjects with patellofemoral pain had significantly increased activity in the vastus medialis oblique and vastus lateralis compared with the healthy subjects during the most demanding phases of the gait cycle, suggesting a generalized quadriceps weakness in the patients with patellofemoral pain. Timing differences were seen in walking and stair ascending with the subjects with patellofemoral pain spending significantly more time in stance compared with the healthy subjects. This may be an attempt to reduce the load on weak quadriceps. These data reflect a generalized quadriceps muscle weakness, rather than the prevailing theory of quadriceps muscle imbalance as an etiology of patellofemoral pain. Therefore, we support the practice of strengthening the entire quadriceps muscle group, rather than attempting to specifically target the vastus medialis oblique.

Isolated Type II Superior Labral Anterior Posterior Lesions Age-Related Outcome of Arthroscopic Fixation

Background Superior labral anterior posterior tears have been described as symptomatic lesions in shoulders of patients of varying ages. It is unknown if age affects clinical outcome of arthroscopic fixation of type II superior labral anterior posterior repairs. Hypothesis Clinical outcome of arthroscopic fixation of isolated type II superior labral anterior posterior tears differs between younger (<40 years) and older (≥40 years) patients. Study Design Cohort study; Level of evidence, 3. Methods Clinical results of arthroscopic fixation of isolated unstable type II superior labral anterior posterior repairs were compared between 25 patients younger than 40 years (group 1) and 25 patients aged 40 years or older (group 2). Patients with concomitant procedures, prior/subsequent shoulder surgeries, and use of non—suture anchor devices were excluded. Outcomes at a minimum 1-year follow-up were assessed using range of motion measurements and the American Shoulder and Elbow Surgeons questionnaire as compared with preoperative data. Ability and time to return to prior level of activity were assessed. Results At a mean 3-year follow-up, there were statistically significant improvements in American Shoulder and Elbow Surgeons scores for both groups (P < .0001) but no significant difference between final American Shoulder and Elbow Surgeons scores (group 1, 91; group 2, 87; P > .198). Both groups demonstrated good or excellent results in >80% of patients. A traumatic mechanism of injury (P = .0346) and presence of osteoarthritis (P = .0401) were independent factors resulting in significantly lower postoperative scores. There were statistically significant differences in preoperative and postoperative range of motion for internal rotation (group 1, P = .0321) and forward elevation (group 2, P = .0003). Return to prior level of activity was similar between younger and older age groups: 80% versus 74%. Time to return to sport was prolonged for group 2 (11.0 months) compared with group 1 (8.45 months). Patients without osteoarthritis were significantly more likely to return to previous levels of activity than were those who had osteoarthritis (P = .0044). Conclusion Good to excellent results and high return to prior level of activity can be expected for the majority of properly indicated patients who undergo isolated type II superior labral anterior posterior repairs, regardless of age. Subtle deficits in range of motion were experienced by both age groups; this did not seem to affect final outcomes. The presence of osteoarthritis was associated with lower American Shoulder and Elbow Surgeons scores and inability to return to prior level of activity. Time to return to activity was prolonged for the older group.

Electromyographic Analysis of Forearm Muscles in Professional and Amateur Golfers

Background No fine-wire electromyography studies have been performed to compare the activity of forearm muscles in professional golfers versus amateur golfers. Hypothesis The fine-wire electromyographic activity of forearm muscles differs between professional and amateur golfers during the different phases of the golf swing. Study Design Controlled laboratory study. Methods Ten male right-handed amateur golfers and 10 male right-handed professional golfers without history of elbow symptoms were tested with fine-wire electromyographic electrodes inserted into the flexor carpi radialis, pronator teres, flexor carpi ulnaris, and extensor carpi radialis brevis muscles of both forearms. Electromyographic data were synchronized with video data, and the muscle activity was expressed as a percentage of maximum manual muscle test activity for each phase of the golf swing. Results Compared with professional golfers, amateur golfers had more muscle activity in the pronator teres of the trail arm (right arm in a right-handed golfer) in the forward swing phase (120.9% maximum manual muscle test vs 57.4% maximum manual muscle test; P =. 04) and a trend toward increased activity in the acceleration phase (104.8% maximum manual muscle test vs 53.1% maximum manual muscle test; P =. 08). In contrast, professional golfers had more muscle activity in the pronator teres of the lead arm (left arm in a right-handed golfer) in the acceleration phase (88.1% maximum manual muscle test vs 36.3% maximum manual muscle test; P =. 03) and a trend toward increased activity in the early follow-through phase (58.1% maximum manual muscle test vs 28.8% maximum manual muscle test; P =. 06). Conclusion Pronator teres muscle activity in the golf swing differs significantly between professional and amateur golfers. Clinical Relevance Exercises with an emphasis on stretching and strengthening of the pronator teres may be useful in treating and/or preventing medial epicondylitis in amateur golfers.