Human evolution and tears of the rotator cuff.

PURPOSE: Humans differ from other great ape species in their propensity to develop tears of the rotator cuff. The aim of this study was to compare the anatomical risk factors for subacromial impingement and rotator cuff tears amongst the great apes and to determine which features may be accentuated in humans and therefore play a more significant role in disease aetiology. METHODS: Orthogonal digital photographs of 22 human, 17 gorilla, 13 chimpanzee and 12 orangutan dry bone scapula specimens oriented in the glenoid plane were taken. Anatomical measurements were preformed using a calibrated digital image technique and the results scaled according to scapula vertebral border length. RESULTS: Of the ten anatomical features associated with subacromial impingement and rotator cuff tears in humans, none were shown to be accentuated and significantly different to the other species studied. However the human supraspinatus fossa was shown to be significantly smaller. CONCLUSIONS: These results indicate that an alternative primary aetiological factor for rotator cuff tears must exist. A reduction in the size of the supraspinatus fossa in human scapulae suggests that structural insufficiency of the supraspinatus or a change in rotator cuff force vectors could play a role.

The management of rotator cuff tears in the elderly.

Rotator cuff tears occur commonly in the elderly causing significant pain and disability. In light of new treatment options developed over recent years, this article reviews the diagnosis and operative options available for this condition.

Thromboprophylaxis in orthopaedic surgery: a clinical review.

Venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), is a common cause of cardiovascular mortality and morbidity. Patients undergoing major orthopaedic surgery, including hip and knee arthroplasty, represent a group that is at particularly high risk for VTE, especially patients with risk factors (age > 60 years, cancer, prior VTE).

The effect of mesenchymal stromal cells on the osseoinduction of impaction grafts.

Revision total hip replacement has a failure rate of up to 25%. Part of the reason for this high failure is the lack of bone stock. In this study, we investigated whether mesenchymal stromal cells (MSCs) or osteoprogenitors (OPs) contribute to bone formation in impacted allograft or an allograft and hydroxyapatite (HA) combination. Eight samples were inserted in the paraspinal muscles of six sheep, which were allograft or an HA/allograft mix, seeded with autologous MSCs, autologous OPs, or no cells (control), and impacted with a clinically relevant force at 3 kN preimplantation. Other groups were HA blocks seeded with or without MSCs. Samples were retrieved at 12 weeks. MSCs incorporated into allograft, HA/allograft, and HA blocks displayed higher mean values of new bone formation compared with the controls, but there was no statistical difference between allograft groups. However, in HA/allograft groups, significantly more new bone was found with MSCs than without cells (p = 0.046) or with OPs (p = 0.028). In the HA blocks, more new bone was found in the MSC group than in the HA block without cells (p = 0.028). In conclusion, MSCs used with combinations of allograft and HA enhance new bone formation in an ovine ectopic site after being subjected to realistic forces that are used during impaction grafting.

Acetabular polyethylene wear and acetabular inclination and femoral offset.

UNLABELLED: Restoration of femoral offset and acetabular inclination may have an effect on polyethylene (PE) wear in THA. We therefore assessed the effect of femoral offset and acetabular inclination (angle) on acetabular conventional (not highly cross-linked) PE wear in uncemented THA. We prospectively followed 43 uncemented THAs for a minimum of 49 months (mean, 64 months; range, 49-88 months). Radiographs were assessed for femoral offset, acetabular inclination, and conventional PE wear. The mean (+/- standard deviation) linear wear rate in all THAs was 0.14 mm/year (+/- 0.01 mm/year) and the mean volumetric wear rate was 53.1 mm(3)/year (+/- 5.5 mm(3)/year). In THAs with an acetabular angle less than 45 degrees , the mean wear was 0.12 mm/year (+/- 0.01 mm/year) compared with 0.18 mm/year (+/- 0.02 mm/year) in those with a reconstructed acetabular angle greater than 45 degrees . Reproduction of a reconstructed femoral offset to within 5 mm of the native femoral offset was associated with a reduction in conventional PE wear (0.12 mm/year versus 0.16 mm/year). Careful placement of the acetabular component to ensure an acetabular angle less than 45 degrees in the reconstructed hip allows for reduced conventional PE wear. LEVEL OF EVIDENCE: Level II, prospective study. See Guidelines for Authors for a complete description of levels of evidence.