Effects of surgical management on multidirectional instability of the shoulder: a meta-analysis.

PURPOSE: The purpose of this study was to assess the effectiveness of arthroscopic and open surgical techniques on the treatment of shoulder multidirectional instability. METHODS: Literature searches were conducted using the databases MEDLINE, Embase, ClinicalTrials.gov, the Cochrane Library, and the Cochrane Central Register of Controlled Trials. Original articles on the surgical management of multidirectional instability were retrieved against selection criteria. Data were extracted and divided into three groups by surgical technique. Proportion and mean meta-analyses were performed for comparison. RESULTS: The available evidence was from 35 level IV and 1 level II studies. The recurrent instability rate was 9.9 % (95 % CI 7.3-12.9 %) in open capsular shift (OCS) group and 6.0 % (95 % CI 3.7-8.9 %) in arthroscopic capsular plication (ACP) group, between which no difference was observed. However, thermal capsular shrinkage (TCS) group resulted in a recurrent instability rate of 23.9 % (95 % CI 16.6-32.2 %), significantly higher than the above two groups. OCS and ACP groups revealed low reoperation rates of approximately 5.2 % (95 % CI 2.7-8.5 %) and 4.8 % (95 % CI 2.3-8.0 %), respectively, which are lower than that in TCS group of 16.9 % (95 % CI 12.4-21.8 %). OCS caused more loss of external rotation than ACP, losing 7.0 (95 % CI 3.3-10.6) degrees versus 2 (95 % CI 0.9-2.4) degrees, respectively. CONCLUSIONS: ACP and OCS techniques have similar primary outcomes, but the former causes less post-operative stiffness. It is suggestible to avoid TCS in the treatment of MDI. LEVEL OF EVIDENCE: Level IV.

The effects of low-intensity pulsed ultrasound on tendon-bone healing in a transosseous-equivalent sheep rotator cuff model.

PURPOSE: The purpose of this study was to examine the effects Low-intensity Pulsed Ultrasound has on initial tendon-bone healing in a clinically relevant extra-articular transosseous-equivalent ovine rotator cuff model. METHODS: Eight skeletally mature wethers, randomly allocated to either control group (n = 4) or treatment group (n = 4), underwent rotator cuff surgery following injury to the infraspinatus tendon. All animals were killed 28 days post surgery to allow examination of early effects of Low-intensity Pulsed Ultrasound treatment. RESULTS: General improvement in histological appearance of tendon-bone integration was noted in the treatment group. Newly formed woven bone with increased osteoblast activity along the bone surface was evident. A continuum was observed between the tendon and bone in an interdigitated fashion with Sharpey's fibres noted in the treatment group. Low-intensity Pulsed Ultrasound treatment also increased bone mineral density at the tendon-bone interface (p < 0.01), while immunohistochemistry results revealed an increase in the protein expression patterns of VEGF (p = 0.038), RUNX2 (p = 0.02) and Smad4 (p = 0.05). CONCLUSIONS: The results of this study indicate that Low-intensity Pulsed Ultrasound may aid in the initial phase of tendon-bone healing process in patients who have undergone rotator cuff repair. This treatment may also be beneficial following other types of reconstructive surgeries involving the tendon-bone interface.

Biomechanical evaluation of four different transosseous-equivalent/suture bridge rotator cuff repairs.

PURPOSE: Evaluate the biomechanical behavior of four variants of the transosseous-equivalent/suture bridge (TOE/SB) repair. METHODS: Four suture bridge (SB) constructs were created using 24 sheep infraspinatus tendon-humerus constructs (n = 6 per technique). The groups were (1) Knotted Standard Suture Bridge (Standard SB)--suture bridge with two medial mattress stitches, (2) Knotted Double Suture Bridge (Double SB)--four medial mattress stitches, (3) Untied Suture Bridge with Medial FT Anchors (Untied SB with FT)--two medial mattress stitches without knots, and (4) Untied Suture Bridge with PushLocks (Untied SB with Pushlocks)--two medial mattress stitches without knots. The contact area footprint was measured with an electronic pressure film prior to dynamic mechanical testing for gapping and testing to failure. RESULTS: The Double SB produced the greatest contact area footprint compared to the other techniques, which did not differ. The Double SB repair with a mean failure load of 456.9N was significantly stronger than the Untied SB with Pushlocks repair at 300N (P = 0.023), the standard SB repair at 295N (P = 0.019), and lastly the Untied SB with FT repair at 284N (P = 0.011). No differences were detected between the two mattress stitch standard SB repair with knots and the knotless two mattress stitch repairs (Untied SB with FT and Untied SB with Pushlocks). Gaps developed during cyclic loading in all repairs apart from the Double SB repair. CONCLUSIONS: The transosseous-equivalent/suture bridge repair with 4 stitches tied in the medial row and maximal lateral suture strand utilization (Double SB) outperformed all other repairs in terms of failure load, tendon-bone contact, and gapping characteristics. The presence of knots in the medial row did not change tendon fixation with respect to failure load, contact area or gapping characteristics.

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.

Suture strength and angle of load application in a suture anchor eyelet.

PURPOSE: To assess the effect of suture material, anchor orientation, and anchor eyelet design on the static loading properties of suture anchors. TYPE OF STUDY: Biomechanical bench study. METHODS: Two metallic suture anchors, Mitek GII (Mitek, Westwood, MA) and Corkscrew (Arthrex, Naples, FL) and a bioabsorbable anchor (Biocorkscrew; Arthrex) were tested with single strand of No. 2 Ethibond (Ethicon, Norderstedt, Germany) or No. 2 FiberWire (Arthrex) suture. Suture pull angle was varied through 0 degrees, 45 degrees, and 90 degrees with the anchor rotation angle in either a sagittal or coronal plane. Constructs were tested to failure using an MTS 858 Bionix testing machine (Material Testing Systems, Eden Prairie, MN). Peak loads, stiffness, energy to peak load, and failure modes were determined for all samples. RESULTS: FiberWire showed superior static mechanical properties when compared with single-strand Ethibond over all testing conditions (P < .05). Suture pull angle had a significant effect on load to failure with both metallic anchors but not on the bioabsorbable anchor (P < .05). CONCLUSIONS: Suture pull angle and anchor rotation angle play an important role in the failure load of suture when placed in an eyelet. The polyaxial nature of the Biocorkscrew eyelet allows for increased degrees of freedom but introduces failure of the suture eyelet as a new failure mode. CLINICAL RELEVANCE: The loading direction and placement of the suture anchor plays a role in the performance of the suture anchor-suture complex.

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. METHODS: The diagnostic ultrasound findings in 336 cases were compared to arthrography, and in 225 cases findings at surgery. RESULTS: A very poor accuracy rate of 0.38 was found for diagnostic ultrasound examination. The sensitivity was 0.24 and specificity was 0.61. CONCLUSIONS: Extreme caution is recommended in the use of diagnostic ultrasound, as currently practised in a general community setting, in diagnosing full-thickness rotator cuff tears.

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.

Should acute anterior dislocations of the shoulder be immobilized in external rotation? A cadaveric study.

The high recurrence rate associated with anterior shoulder dislocations may reflect inadequate healing of a Bankart lesion when the arm is immobilized in internal rotation. The effect of external rotation (ER) of the humerus on the glenoid-labrum contact of Bankart lesions was examined in 10 human cadaveric shoulders. The contact force between the glenoid labrum and the glenoid was measured in 60 degrees of internal rotation, neutral rotation, and 45 degrees of ER in 10 human cadaveric shoulders. No detectable contact force was found with the arm in internal rotation. The contact force increased as the arm passed through neutral rotation and reached a maximum at 45 degrees of ER. The contact force returned to 0 g when the arm was returned to neutral rotation. The mean contact force at 45 degrees of ER was 83.5 g. External rotation significantly increases the labrum-glenoid contact force and may influence the healing of a Bankart lesion.