Postoperative changes in the tensor fascia lata muscle after using the modified anterolateral approach for total hip arthroplasty.

The modified Watson-Jones approach to the hip has been described as a minimally invasive approach with the potential for fewer postoperative complications than the traditional approach. Because the approach relies on an intermuscular rather than an internervous plane, there is potential for injury to the superior gluteal nerve. The aim of this study was to evaluate incidence of tensor fascia lata (TFL) denervation in patients undergoing this approach. Twenty-six patients underwent total hip arthroplasty (THA) using a modified anterolateral approach. Postoperative MRIs were analyzed for signs of muscle denervation including atrophy, hypertrophy and fat replacement. At a median follow-up of 9.3months, 74% of patients exhibited either atrophy or hypertrophy of the TFL and 42% exhibited fat replacement on MRI.

Stasis predisposes ileal pouch inflammation in a rat model of ileal pouch-anal anastomosis.

BACKGROUND: While restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) has become the definitive surgical treatment for patients suffering from chronic ulcerative colitis (CUC), pouchitis still remains a major late complication. Fecal stasis has been implicated in the etiology of ileal inflammation; however, the mechanism(s) remain unclear, in part due to the lack of an animal model. Our goal was to surgically mimic the IPAA procedure in a rat to investigate the hypothesis that stasis leads to biochemical changes that predispose the ileal pouch to inflammation. MATERIALS AND METHODS: Thirty-two Sprague-Dawley rats underwent total colectomy with either straight ileorectal (IRA) or IPAA, and 11 nonoperated rats served as controls (Controls). Twenty-one d postoperatively, 48 h serial barium radiographs and 12 h charcoal transit follow-through studies were performed. Following sacrifice, ileal tissue was harvested for the measurement of myeloperoxidase activity (MPO) activity, intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) mRNA levels, and histology. RESULTS: Serial barium radiographs showed stasis in the ileal pouch compared with IRA animals, and charcoal transit times that were two times longer (P ≤ 0.05) than that in the straight IRA rats. Ileal pouch MPO levels were significantly elevated in the IPAA rats compared with the straight IRA rats. ICAM-1 and VCAM-1 mRNA levels were not associated with neutrophil infiltration. CONCLUSIONS: These studies showed that ileal pouch stasis predisposes biochemical and histological evidence of ileal pouch mucosal inflammation. Studies such as this may provide the rationale for novel, adjunct therapies for the management of pouchitis in patients having undergone IPAA for CUC.

Genetic variation in the patterns of skeletal progenitor cell differentiation and progression during endochondral bone formation affects the rate of fracture healing.

These studies examined how genetic differences that regulate architectural and bone material properties would be expressed during fracture healing and determine whether any of these features would affect rates of healing as defined by regain of strength. Controlled fractures were generated in three inbred strains of mice: A/J, C57Bl/6J (B6), and C3H/HeJ (C3H). Both the A/J and B6 strains showed faster healing than the C3H strain based on regains in strength and stiffness. Strain-specific architectural features such as moment of inertia, cross-sectional area, and cortical thickness were all recapitulated during the development of the callus tissues. None of these traits were directly relatable to rates of fracture healing. However, rates of healing were related to variations in the temporal patterns of chondrogenic and osteogenic lineage development. The B6 strain expressed the highest percentage of cartilage gene products and had the longest period of chondrocyte maturation and hypertrophy. The slowest healing strain (C3H) had the shortest period of chondrogenic development and earliest initiation of osteogenic development. Although the A/J strain showed an almost identical pattern of chondrogenic development as the C3H strain, A/J initiated osteogenic development several days later than C3H during fracture healing. Long bone growth plates at 28 days after birth showed similar strain-specific variation in cartilage tissue development as seen in fracture healing. Thus, the B6 strain had the largest growth plate heights, cell numbers per column, and the largest cell size, whereas the C3H columns were the shortest, had the smallest number of cells per column, and showed the smallest cell sizes. These results show that (1) different strains of mice express variations of skeletal stem cell lineage differentiation and (2) that these variations affect the rate of fracture healing.