The effect of ankle joint immobilization on lower limb venous flow.

BACKGROUND: Below-knee cast immobilization is associated with an increased risk of developing deep vein thrombosis secondary to venous stasis. We investigated the effect of weight-bearing in a below-knee cast or pneumatic walking boot on lower limb venous blood flow. METHODS: Duplex ultrasonography was used to measure venous blood flow in the popliteal vein of 10 healthy volunteers. Venous blood flow was measured while at rest, ambulating non-weight-bearing, partial weight-bearing, and full weight-bearing. Measurements were performed without ankle joint immobilization, with the ankle immobilized in a neutral cast, and with the ankle immobilized in a pneumatic walking boot in both neutral and equinus. RESULTS: There was no significant reduction in venous blood flow measurements between full weight-bearing without ankle joint immobilization and full weight-bearing in a neutral cast or neutral pneumatic walking boot. However, venous blood flow was reduced when partial weight-bearing (50%) and when full weight-bearing in a pneumatic walking boot in equinus. CONCLUSION: These results demonstrate that venous blood flow returned to normal levels when the subjects were permitted to fully bear weight in below-knee casts or walking boots, provided that the ankle joint was not in equinus. CLINICAL RELEVANCE: Weight-bearing status and ankle joint position should be appreciated during decisions for the provision of chemical thromboprophylaxis.

Minimally invasive arthrodesis of the first metatarsophalangeal joint for hallux rigidus.

BACKGROUND: First metatarsophalangeal joint arthrodesis plays a significant role in the management of symptomatic hallux rigidus. Several open and one percutaneous technique have been described in the literature. The authors present a minimally invasive technique, not previously published in the UK with patient-reported outcomes. METHODS: A total of 26 cases of are presented in this prospective, continuous series. Clinical outcome and patient satisfaction were assessed by the Manchester-Oxford Foot Questionnaire (MOXFQ) preoperatively and at most recent follow up (maximum 20 months). Radiographic and clinical evaluation of fusion was also assessed with a fusion rate of 93%. RESULTS: The MOXFQ score for cases where fusion was achieved improved from a mean of 42 points to 18 points at last follow up (p<0.05). Patient satisfaction was overall very good. CONCLUSIONS: This minimally invasive technique is simple and can achieve results similar or better than open techniques in experienced hands. Postoperative care requirements are minimal and both clinical and patient-reported outcome show significant improvement in this series.

Computer assisted pelvic surgery: registration based on a modified external fixator.

A fundamental step in Computer Assisted Surgery (CAS) is the registration, when the preoperative virtual data and the corresponding operative anatomy of the region of interest are merged. To provide exact landmarks for anatomical registration, a tubular external fixator was modified. Two intact pelvic bones (one artificial foam pelvis and one cadaver specimen) were used for the experimental setup. Registration was carried out using a standardized protocol for anatomy-based registration in the control group; anatomical registration was achieved using a modified external fixator in the study group. This external fixator had titanium fiducials wedged into the fixator carbon tubes serving as landmarks for paired-point registration. The tubes were used for surface registration. The standard anterior pelvis fixator assembly was augmented with additional bilateral tubes oriented towards the posterior, enabling registration of the sacroiliac areas. The accuracy of registration was checked by "reversed verification", where the examiner used only the screen display to control the virtual position of the pointer tip in relation to selected landmarks. By virtual matching, the real distance was measured with a digital caliper. We defined the verification as "accurate" when the residual distance was less than 1 mm; "acceptable" when it was between 1 mm and 2 mm; and "insufficient" when it exceeded 2 mm. The paired T-test with significance levels of p < 0.05 was used for statistical analysis. The anatomical registration based on the external fixator landmarks was statistically as accurate as that obtained using anatomical landmarks on the pelvic bone. This study concludes that the external fixator, a conventional tool in the management of acute traumatic pelvic instability, can also be useful for landmark registration in CAS.