Anatomy and biomechanics of gluteus maximus and the thoracolumbar fascia at the sacroiliac joint.

Biomechanical models predict that recruitment of gluteus maximus (GMax) will exert a compressive force across the sacroiliac joint (SIJ), yet this muscle requires morphologic assessment. The aims of this study were to document GMax's proximal attachments and assess their capacity to generate forces including compressive force at the SIJ. In 11 embalmed cadaver limbs, attachments of GMax crossing the SIJ were dissected and their fascicle orientation, length and attachment volume documented. The physiological cross-sectional area (PCSA) of each attachment was calculated along with its estimated maximum force at the SIJ and lumbar spine. GMax fascicles originated from the gluteus medius fascia, ilium, thoracolumbar fascia, erector spinae aponeurosis, sacrum, coccyx, dorsal sacroiliac and sacrotuberous ligaments in all specimens. Their mean fascicle orientation ranged from 32 to 45° below horizontal and mean length from 11 to 18 cm. The mean total PCSA of GMax was 26 cm(2) (range 16-36), of which 70% crossed the SIJ. The average maximum force predicted to be generated by GMax's total attachments crossing each SIJ was 891 N (range 572-1,215), of which 70% (702 N: range 450-1,009) could act perpendicular to the plane of the SIJ. The capacity of GMax to generate an extensor moment at lower lumbar segments was estimated at 4 Nm (range 2-9.5). GMax may generate compressive forces at the SIJ through its bony and fibrous attachments. These may assist effective load transfer between lower limbs and trunk.

Neck of femur fractures in the over 90s: a select group of patients who require prompt surgical intervention for optimal results.

BACKGROUND: Patients in the extremes of old age with a femoral neck fracture represent a challenging subgroup, and are thought to be associated with poorer outcomes due to increased numbers of comorbidities. Whilst many studies are aimed at determining the optimum time for surgical fixation, there is no agreed consensus for those over 90. The aim of this study is to report the surgical outcome of this population, to understand the role surgical timing may have on operative outcomes using the orthopaedic POSSUM scoring system and to identify whether medical optimization occurs during the period of admission before surgery. MATERIALS AND METHODS: We conducted a prospective observational study; data was collected from two district general hospitals over 32 consecutive months. All patients aged 90 and above who were deemed suitable for surgical fixation were included. Each one had their orthopaedic POSSUM score calculated at admission and at surgery, using their computerised and paper medical records. Assessment of outcome was based on morbidity and mortality at 30 days. RESULTS: A total of 146 consecutive patients above the age of 90 underwent surgery and were followed. The average age of the patients was 93 years, 123 (84 %) were female and 23 (16%) male. Sixty-one patients were operated on within 24 h from admission, 52 patients within 24 and 48 h and 33 had surgery after 48 h from admission. In total, 21 deaths (14.4%) were recorded and 81 patients (55.5%) had a post-operative complication within 30 days. The orthopaedic POSSUM scoring system predicted 30-day mortality in 23 patients and morbidity in 83 patients. This gave observed to predicted ratios of 0.91 and 0.98 respectively. Overall, there was a small improvement in physiological scores taken just prior to surgery compared to those at admission. Mortality and morbidity rates were higher for those operated on or after 24 and 48-h cutoffs compared to those proceeding to surgery within 24 h (P = 0.071 and P = 0.021 respectively and P = 0.048 and P = 0.00011 respectively). When stratified according to their POSSUM scores, patients with scores of 41+ and surgery after 48 h had a significantly higher mortality rate than if they had surgery earlier (P = 0.038). Morbidity rates rose after 24 h of surgical delay (P = 0.026). Patients with a total POSSUM score between 33 and 40 exhibited a higher morbidity after a 24-h delay to surgery (P = 0.0064). CONCLUSION: As life expectancy increases, older patients are becoming commoner in our hospital systems. We believe the orthopaedic POSSUM scoring system can be used as an adjuvant tool in prioritising surgical need, and allow for a more impartial evaluation when changes to practice are made. Our findings show that timing of surgery has an important bearing on mortality and morbidity after hip surgery, and older patients with higher orthopaedic POSSUM scores are sensitive to delays in surgery.