A new minimal-invasive approach for total hip replacement in sheep.

BACKGROUND: Over the last 50 years arthroplasty became the gold-standard treatment for disabling conditions of the coxofemoral joint. Variations of anterior, lateral, and dorsal incision have been applied, but as each approach requires the incision and reflection of various muscles to gain adequate exposure of the joint results are still controversial. OBJECTIVE: The purpose of this study was to develop a minimal-invasive, tissue-sparing approach in sheep with reduced risks in animal testing. METHODS: 12 mature sheep underwent hip surgery as part of a study to evaluate a hip resurfacing system. In line with the preliminary cadaveric tests a modified, minimal-invasive, musclepreserving surgical approach was sought after. RESULTS: We developed a surgical approach to the coxofemoral joint in sheep using only blunt tissue dissection after skin incision without any limitations in joint exposure or increased blood loss/duration of surgery. CONCLUSION: Even though limitations occur and femoral orientation in sheep differs from man, joint forces have similar relative directions to the bone with similar bony and vascular anatomy. Therefore, this minimal-invasive muscle preserving approach might be a safe and comparable alternative in still inevitable animal testing.

Sympathetic dysfunction in long-term complex regional pain syndrome.

OBJECTIVE: Malfunction of the sympathetic nervous system (SNS) is common in early complex regional pain syndrome type I (CRPS I). This study was designed to evaluate the function of the SNS in patients with chronic CRPS I and to correlate the obtained data with hand function measurements. MATERIALS AND METHODS: Thirty-two patients of both the sexes in whom the diagnosis of CRPS I of the upper extremity had been established for at least 3 years before they were included in the study. Besides a hand outcomes questionnaire [Michigan Hand Outcome Questionnaire, (MHQ)] the patients underwent a standardized testing of the peripheral sympathetic nervous system (pSNS) using laser Doppler flowmetry (LDF). RESULTS: Mean time since initial diagnosis was 4.6+/-2.1 years. The mean MHQ score of the affected limb was 57.3+/-17 compared with 69.4+/-13.7 for the unaffected hand (P=0.002). Twenty patients (62.5%) still demonstrated pathologic results regarding the pSNS function (mean sympathetic reflex 0.18+/-0.11, normal range>0.38). We found no statistically significant correlation between pSNS function either with the clinical outcome as measured by MHQ (r=0.246; P=0.175), or with the level of pain (r=0.132; P=0.473). CONCLUSIONS: Even 5 years after the diagnosis of CRPS I of the upper extremity we detected significant impairments of the pSNS in nearly two thirds of our patients. Patients still have pain and present with a significant deterioration of their hand function in comparison with the not affected hand. In our study we could not identify any correlation between pSNS function and clinical outcome as measured by MHQ.