Impingement and stability of total hip arthroplasty versus femoral head resurfacing using a cadaveric robotics model.

We identified and compared the impingent-free range of motion (ROM) and subluxation potential for native hip, femoral head resurfacing (FHR), and total hip arthroplasty (THA). These constructs were also compared both with and without soft tissue to elucidate the role of the soft tissue. Five fresh-frozen bilateral hip specimens were mounted to a six-degree of freedom robotic manipulator. Under load-control parameters, in vivo mechanics were recreated to evaluate impingement free ROM, and the subluxation potential in two "at risk" positions for native hip, FHR, and THA. Impingement-free ROM of the skeletonized THA was greater than FHR for the anterior subluxation position. For skeletonized posterior subluxations, stability for THA and FHR constructs were similar, while a different pattern was observed for specimens with soft tissues intact. FHR constructs were more stable than THA constructs for both anterior and posterior subluxations. When the femoral neck is intact the joint has an earlier impingement profile placing the hip at risk for subluxation. However, FHR design was shown to be more stable than THA only when soft tissues were intact.

A prospective, multi-center, randomised trial to evaluate the efficacy of a cryopneumatic device on total knee arthroplasty recovery.

Pain, swelling and inflammation are expected during the recovery from total knee arthroplasty (TKA) surgery. The severity of these factors and how a patient copes with them may determine the ultimate outcome of a TKA. Cryotherapy and compression are frequently used modalities to mitigate these commonly experienced sequelae. However, their effect on range of motion, functional testing, and narcotic consumption has not been well-studied. A prospective, multi-center, randomised trial was conducted to evaluate the effect of a cryopneumatic device on post-operative TKA recovery. Patients were randomised to treatment with a cryopneumatic device or ice with static compression. A total of 280 patients were enrolled at 11 international sites. Both treatments were initiated within three hours post-operation and used at least four times per day for two weeks. The cryopneumatic device was titrated for cooling and pressure by the patient to their comfort level. Patients were evaluated by physical therapists blinded to the treatment arm. Range of motion (ROM), knee girth, six minute walk test (6MWT) and timed up and go test (TUG) were measured pre-operatively, two- and six-weeks post-operatively. A visual analog pain score and narcotic consumption was also measured post-operatively. At two weeks post-operatively, both the treatment and control groups had diminished ROM and function compared to pre-operatively. Both groups had increased knee girth compared to pre- operatively. There was no significant difference in ROM, 6MWT, TUG, or knee girth between the 2 groups. We did find a significantly lower amount of narcotic consumption (509 mg morphine equivalents) in the treatment group compared with the control group (680 mg morphine equivalents) at up to two weeks postop, when the cryopneumatic device was being used (p < 0.05). Between two and six weeks, there was no difference in the total amount of narcotics consumed between the two groups. At six weeks, there was a trend toward a greater distance walked in the 6MWT in the treatment group (29.4 meters versus 7.9 meters, p = 0.13). There was a significant difference in the satisfaction scores of patients with their cooling regimen, with greater satisfaction in the treatment group (p < 0.0001). There was no difference in ROM, TUG, VAS, or knee girth at six weeks. There was no difference in adverse events or compliance between the two groups. A cryopneumatic device used after TKA appeared to decrease the need for narcotic medication from hospital discharge to 2 weeks post-operatively. There was also a trend toward a greater distance walked in the 6MWT. Patient satisfaction with the cryopneumatic cooling regimen was significantly higher than with the control treatment.

A computer model of the position of the combined component in the prevention of impingement in total hip replacement.

Dislocation remains a major concern after total hip replacement, and is often attributed to malposition of the components. The optimum position for placement of the components remains uncertain. We have attempted to identify a relatively safe zone in which movement of the hip will occur without impingement, even if one component is positioned incorrectly. A three-dimensional computer model was designed to simulate impingement and used to examine 125 combinations of positioning of the components in order to allow maximum movement without impingement. Increase in acetabular and/or femoral anteversion allowed greater internal rotation before impingement occurred, but decreases the amount of external rotation. A decrease in abduction of the acetabular components increased internal rotation while decreasing external rotation. Although some correction for malposition was allowable on the opposite side of the joint, extreme degrees could not be corrected because of bony impingement. We introduce the concept of combined component position, in which anteversion and abduction of the acetabular component, along with femoral anteversion, are all defined as critical elements for stability.

Cranial nerve palsy as a complication of operative traction.

STUDY DESIGN: Case report. OBJECTIVE: This report documents one case of diplopia from abducens (sixth cranial) nerve palsy after spinal surgery using a Jackson table and cranial traction. SUMMARY OF BACKGROUND DATA: Cranial nerve deficits have frequently been described in the orthopedic literature after trauma, halo pelvic traction, and halo skeletal fixation. The theorized mechanism of injury to the abducens nerve involves stretch or traction force, which causes localized ischemia or a change in nerve position. An extensive literature search failed to show this type of injury using Gardner-Wells tongs in conjunction with the Jackson table. METHODS: This is a case report that included a chart review, examination of the patient, and a literature search. RESULTS: The patient had complete spontaneous resolution of abducens nerve dysfunction within 6 months. CONCLUSIONS: It is important for the surgeon to be aware of this potential complication and to inform patients who have diplopia that develops from abducens nerve palsy that most of these cranial nerve deficits spontaneously improve.

Comparing ridge resorption with various surgical techniques in immediate dentures.

The three surgical techniques of simple tooth extraction and labial plate and intraseptal alveoloplasty were compared. The results were confirmed by statistical analysis. The conclusion of this study clearly indicated that simple tooth extraction is the best surgical approach to be followed to preserve as much of the residual alveolar ridge as possible.