Fixation of greater tuberosity fractures: a biomechanical comparison of three techniques

The fixation of displaced greater tuberosity fractures with 5-0 Fiberwire, Fiberwire tape, and 5-0 Ethibond sutures was compared in 12 pairs of cadaveric humeri. A simulated fracture was created and fixed with suture in a figure-of-eight pattern. The tuberosity was cyclically loaded and its displacement measured. There was no statistical difference in fixation stability between the three suture types.     

Magnetic resonance imaging evaluation of the ulnar collateral ligament in young baseball pitchers less than 18 years of age

INTRODUCTION: It has been shown that the asymptomatic, dominant elbow of professional baseball pitchers can demonstrate magnetic resonance (MR) imaging signal abnormalities of the ulnar collateral ligament (UCL) consistent with a strain. The purpose of this study was to determine if younger, asymptomatic, adolescent baseball pitchers exhibit similar signal abnormalities in the UCL. METHODS: Magnetic resonance images of both elbows of 14 asymptomatic, young male baseball pitchers (ranging in age from 12 to 20 years) were performed on an outpatient basis using a 1.5-T Sigma MRI unit with a dedicated extremity coil to obtain T1 and T2 coronal and axial images which were subsequently evaluated by a musculoskeletal radiologist. Chronic tears of the UCL were suspected if the signal was attenuated or absent. Magnetic resonance images of the UCL were also evaluated for high-intensity signal or thinning. Morphologic changes such as complete tears, avulsions or thickening were identified. The images were classified into 4 grades from 0 to 3 depending on the degree of signal abnormality. RESULTS: No discrete tears were found in any of the subjects. For the dominant pitching arm, 4 of 14 subjects had increased thickness of the ulnar collateral ligament, 3 of 14 demonstrated Grade 1 changes, and 11 of 14 demonstrated no abnormal signal within the ligament. No focal tears were present in any of the subjects. Contralateral elbows in 13 of 14 patients demonstrated Grade 0 signals with 1 patient demonstrating morphological thickening of the ligament without increased signal. DISCUSSION: Signal abnormalities in the throwing elbow of asymptomatic, adolescent pitchers were uncommon. These pitchers may not have experienced sufficient pitching time to develop changes in the UCL.     

A biodegradable button to augment suture attachment in rotator cuff repair

Recent experimental studies suggest that the use of suture anchors for rotator cuff tear (RCT) repair transfers the "weak link" to the suture-tendon interface where failure occurs as the sutures cut through the tendon. The purpose of this study was to evaluate the effect of using a suture augmentation button on the fixation strength of rotator cuff tendon repair. A 1.5 cm by 2 cm defect was created in the supraspinatus tendon of seven cadaveric shoulder pairs and two suture anchors inserted in each humerus for suture attachment. For one of each pair, the defect was repaired with sutures placed in a horizontal mattress configuration. The other side was repaired with the sutures being passed through low profile, bioabsorbable buttons placed on the bursal tendon surface prior to knot tying. The supraspinatus tendon was cyclically loaded at a physiologic rate and load (33 mm/sec and 180 N, respectively). The number of loading cycles was recorded when the specimens developed 0.75 cm and 1.5 cm gaps at the repair site. The specimens were then tested to failure. Specimens in the unaugmented group developed 0.75 cm and 1.5 cm gaps at an average of 135 cycles and 362 cycles, respectively. The button augmented group developed these gaps at average of 420 cycles and 708 cycles, respectively. These differences were statistically significant (p < 0.05). The gaps progressively increased in all specimens, which eventually failed by suture cutting through tendon in all specimens. This study demonstrates that in vitro, suture augmentation with a low profile, bioabsorbable button provides significantly enhanced fixation when using suture anchors to repair torn rotator cuff tendon. This device may be a useful adjunct to current methods of rotator cuff repair.     

The interaction between the whipstitch sutures of multi-strand ACL grafts and interference screw fixation

In a recent experiment examining the effect of interference screw sizing on the fixation stability of multi-strand anterior cruciate ligament grafts, we noticed a large variation in fixation strengths and attributed it to the suturing of the grafts and its interaction with the screw. We performed an experiment using interference screws for fixation of hamstring grafts within a bone tunnel model to compare how the presence of sutures affected graft fixation. We found that having sutures along the region of the graft that contacts the screw within the bone tunnel can increase graft fixation strength 100%.     

An examination of the physical characteristics leading to angioplasty balloon rupture

Six polyvinyl chloride and six polyethylene angioplasty balloons were inflated six times each under laboratory conditions. Outside diameter of the balloons was measured on initial and final inflations; volume was measured by water displacement at each inflation. In addition, three balloons in either group were constricted with a silk suture around the midportion. Balloons were then intentionally ruptured and the rupture site recorded. The diameters of the polyvinyl chloride balloons increased over six inflations, while they remained relatively constant for the polyethylene balloons. Rupture sites were in the area of the balloon that had the greatest outside diameter, and the tears were longitudinal.     

Ultrasound of the whole breast utilizing a dedicated automated breast scanner

Innovations in design of a dedicated breast scanner resulted in automation of the scanning process, the production of high resolution images of the whole breast and an efficient mode of image review. The results of clinical evaluation of the prototype of this breast scanner investigating normal breasts as well as benign and malignant breast lesions are presented.