Jerome Goldberg

Structural Properties of the Intact and the Reconstructed Coracoclavicular Ligament Complex

Numerous procedures have been described for the operative management of acromioclavicular joint injuries, but surprisingly little information is available on the ultimate mechanical behavior of the native coracoclavicular ligament complex or on the various methods of reconstruction. We tested 19 fresh-frozen cadaveric bone-ligament-bone preparations of the coracoclavicular ligament in uniaxial tension at 25 mm/min until failure. Seven specimens were left intact, six had the trapezoid ligament sectioned, and six had the conoid ligament sectioned. Reconstruction of the coracoclavicular ligament was achieved using coracoacromial ligament transfers, woven polyester slings, suture anchors, and Bosworth screws; all reconstructions were also tested to failure. The intact coracoclavicular ligament failed by avulsion or midsubstance tear at 500 (134) N, with a stiffness of 103 (30) N/mm and elongation to failure of 7.7 (1.9) mm. There was no significant difference between the contributions of the conoid or trapezoid ligaments in this loading configuration. Coracoclavicular slings and suture anchors provided strength similar to that of the coracoclavicular ligament, but with significantly greater deformations (14 to 26 mm). Screw fixation resulted in comparable stiffness and superior strength to the coracoclavicular ligament, but only if bicortical purchase was obtained. Coracoacromial ligament transfers were the weakest and least stiff, and augmentation with another form of coracoclavicular fixation is recommended. These results provide a useful baseline for comparison of the initial performance of reconstructive techniques with the performance of the native coracoclavicular ligament.

Type 2 fractures of the distal clavicle: A new surgical technique

Neer type 2 fractures of the distal clavicle have a high rate of nonunion and delayed union. In this series nine cases of coracoclavicular ligament reconstruction with Dacron graft material led to union at the fracture site. All patients had no symptoms and returned to full activity. This technique allows for stable fixation with early mobilization and return to work and sports.

Surgical management of large rotator cuff tears combined with instability in elite rugby football players

Large rotator cuff tears are extremely uncommon in young people and when they occur they may be associated with shoulder instability. This paper reports on a series of six elite rugby union and rugby league footballers who presented with shoulder instability and large rotator cuff tears. They were treated with a two stage procedure: an open rotator cuff repair followed by an open shoulder stabilisation some 10 weeks later. All had successful outcomes. The paper also highlights the risk of tearing the rotator cuff when a patient continues to play contact sport with an untreated unstable shoulder.

Biomechanical Performance of Bankart Repairs in a Human Cadaveric Shoulder Model

The objective of this study was to develop a method to evaluate the biomechanical performance of Bankart repairs in a human cadaveric shoulder in a clinically relevant orientation. Twenty fresh-frozen human cadaveric shoulder girdles were used to compare the biomechanical performance of intact anteroinferior capsulolabral complexes with the biomechanical performance of three Bankart lesion reconstruction techniques. Repairs were performed on surgically created Bankart lesions. Evaluations were performed with the shoulders in glenohumeral abduction and external rotation. The repair techniques employed interosseous sutures, Mitek GII suture anchors, or Acufex T-Fix devices. The suture material used in all repairs was No. 2 Ti-Cron. The biomechanical performance of the three reconstruction techniques did not differ, but each was significantly inferior compared with that of the intact shoulder samples. The interosseous repairs failed by suture pullout through soft tissue. Repairs in the Mitek GII group failed by pullout of the suture anchors, suture breakage, or pullout of the suture through soft tissue. Repairs in the T-Fix group failed by pullout of the suture through soft tissue or failure of the polymer portion of the T-Fix suture.

Prevention of Heterotopic Bone Formation in High Risk Patients Post-Total Hip Arthroplasty

A retrospective study was carried out to evaluate prophylaxis for heterotopic ossification (HO) about the hip joint post total hip arthroplasty (THA). Between 1990 and 1996, 20 patients with known risk for developing HO were treated prophylactically to prevent this complication. Patients at risk were divided into 3 groups based on risk factors for HO formation (previous ipsilateral hip HO formation, previous contralateral hip HO formation and bilateral hypertrophic osteoarthritis) Single fraction radiotherapy of 600, 700 or 800 cGy was administered postoperatively to all patients. The aim was to irradiate all patients within 72 hours of THA. 12 (60%) patients received in addition a short course of postoperative indomethacin for less than 13 days. Patients in this study were investigated for the following treatment variables: relative risk for forming HO, radiotherapy doses administered, time delays between surgery and irradiation, combined radiotherapy and indomethacin treatment versus radiotherapy alone, and surgical approach used for THA. Heterotopic ossification in patients was measured radiographically by use of the Brooker grading sytem, and was assessed clinically by use of the Harris Hip Score (HHS). A significant difference was found between relative risk groups (p = 0.02). Patients with previous HO formation in the ipsilateral hip joint were at greater risk of developing HO than those with previous contralateral HO formation. Moreover both of these groups were at greater risk than those with advanced bilateral hypertrophic osteoarthritis. Other variables studied showed differences that were not significant due to small sample numbers. This study, though limited by sample number, addresses questions regarding effective radiotherapy dosage, time delays acceptable before irradiation postoperatively, usefulness of short course postoperative indomethacin, and preferred operative approaches to minimise HO.

Mechanical properties of the rotator cuff: response to cyclic loading at varying abduction angles

The rotator cuff is loaded under static as well as dynamic conditions. Whilst the static properties of the rotator cuff muscle-tendon junctions have been reported, the dynamic mechanical behaviour has not. This study reports the dynamic mechanical properties with varying abduction angles in a human cadaver rotator cuff. No significant effect was found with varying the angle of testing or in the presence of a tear in the tendon. The supraspinatus was found to be the stiffest of the rotator cuff tendons followed by the subscapularis and infraspinatus.

Role of community diagnostic ultrasound examination in the diagnosis of full-thickness rotator cuff tears

Background:  Diagnostic ultrasound examination has become the most commonly used investigation in Australia for diagnosing rotator cuff tears. The authors felt that the results of such investigations were often inaccurate in their clinical practices.

Anatomic and Biomechanical Study of the Biceps Vinculum, a Structure Within the Biceps Sheath

PURPOSE To evaluate the anatomic, biomechanical, and histologic properties of the biceps vinculum and its potential role as a restraint to distal migration of the biceps after tenotomy. METHODS Eight human shoulders were dissected to define the anatomic parameters of the biceps vinculum. Histologic studies were performed by sectioning through the vinculum-tendon attachment and performing H&E staining. The strength of the vinculum was tested biomechanically after sectioning the biceps origin and applying a uniaxial tension at a rate of 1 mm/s until failure. RESULTS With regard to anatomy, the vinculum was present in all specimens, attached to the biceps tendon and proximal humerus. Excursion testing showed that the vinculum prevented the biceps origin from migrating distal to the groove entrance. The mean dimensions of the structures and excursion were as follows: biceps origin to vinculum, 43.4 mm; vinculum width on biceps side, 46.2 mm; vinculum width on bone side, 69.3 mm; length of tendon with proximal pull, 42.6 mm; and length of tendon with distal pull, 2.25 mm. With regard to histology, the membranous tissue of the biceps vinculum consisted of loose soft tissue with fat, arteries, and veins. The vinculum was seen to loosely attach to the biceps tendon and more intimately attach to the periosteal/bone side. With regard to biomechanical testing, the maximum force to failure of the vinculum was variable, ranging from 17.4 N to 227.6 N, with a mean value of 102.7 +/- 76 N. CONCLUSIONS The biceps vinculum was a consistent membranous structure intimately associated with the biceps tendon and attached to the proximal humerus. After tenotomy at the biceps origin, the vinculum prevented distal migration of the proximal biceps tendon past the groove entrance in all specimens. Biomechanical testing showed that the vinculum provided variable resistance to distal pull. CLINICAL RELEVANCE The properties described may help to explain why biceps tenotomy does not routinely result in a Popeye biceps deformity.

Boundary conditions at the tendon–bone interface

The reconstruction of a tendon–bone interface, as in rotator-cuff repairs, remains a challenging surgical problem. There is however, little data to show what effect joint position or repair loading under physiological conditions have on the repaired tendon–bone interface. A change in the amount of contact area or load at the tendon–bone interface may influence healing. In this study we investigated the effect of limb position and boundary conditions on the tendon–bone interface in an in vitro rabbit tendon–bone repair model using both unlinked and linked suture repairs.