Novel classification of knee osteoarthritis severity based on spatiotemporal gait analysis.

OBJECTIVE: To describe a novel classification method for knee osteoarthritis (OA) based on spatiotemporal gait analysis. METHODS: Gait analysis was initially performed on 2911 knee OA patients. Females and males were analyzed separately because of the influence of body height on spatiotemporal parameters. The analysis included the three stages of clustering, classification and clinical validation. Clustering of gait analysis to four groups was applied using the kmeans method. Two-thirds of the patients were used to create a simplified classification tree algorithm, and the model's accuracy was validated by the remaining one-third. Clinical validation of the classification method was done by the short form 36 Health Survey (SF-36) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaires. RESULTS: The clustering algorithm divided the data into four groups according to severity of gait difficulties. The classification tree algorithm used stride length and cadence as predicting variables for classification. The correct classification accuracy was 89.5%, and 90.8% for females and males, respectively. Clinical data and number of total joint replacements correlated well with severity group assignment. For example, the percentages of total knee replacement (TKR) within 1 year after gait analysis for females were 1.4%, 2.8%, 4.1% and 8.2% for knee OA gait grades 1-4, respectively. Radiographic grading by Kellgren and Lawrence was found to be associated with the gait analysis grading system. CONCLUSIONS: Spatiotemporal gait analysis objectively classifies patients with knee OA according to disease severity. That method correlates with radiographic evaluation, the level of pain, function, number of TKR.

Biomechanical evaluation of transverse acetabular fracture fixation.

The purpose of this two-part biomechanical study was to evaluate various fixation methods for transverse acetabular fractures in a synthetic pelvic model. In Part 1, 40 transverse acetabular fractures were repaired with anterior column plating using 10-hole curved reconstructions plates with one of four screw configurations to evaluate the effect of screw placement and number on fracture fixation stiffness. In Part 2, 36 transverse acetabular fractures were repaired with one of six fixation methods using combinations of contoured plates and column screws to stabilize the anterior column, the posterior column, or both. Each repaired acetabulum was loaded via a hemiarthroplasty in a direction consistent with stance phase. Fixation stiffness was measured from the force-displacement curve for each construct. In Part 1, there was no significant difference in fixation stiffness afforded by any of the constructs. However, the stiffest construct resulted from two screws on each side of the fracture site: one placed as close to the fracture site as allowed (one empty screw hole adjacent to the fracture) and the second at the end of the plate. In Part 2, the constructs that concomitantly stabilized anterior and posterior columns were significantly stiffer than were those addressing either the anterior or posterior column alone, regardless of the number of plates applied. The stiffest construct combined a posterior column plate with an anterior column screw. Because no significant change in stiffness occurred with the addition of a third set of screws, two screws on each side of the fracture site appear to provide sufficient stability with acetabular plating. Concurrent fixation of anterior and posterior columns of transverse acetabular fractures provides the greatest resistance to postoperative loss of reduction in this model.

Treatment of humeral fractures by closed reduction and retrograde intramedullary Ender nails.

A retrospective review of 94 humeral shaft fractures stabilized with retrograde Ender nails was performed to determine the safety and efficacy of this technique. Follow-up averaged 71 weeks. Eighty-six (91.5%) healed with no additional intervention (average: 14 weeks). There were eight (8.5%) nonunions. The functional results were good in 74 (81%), fair in 12 (13%), and poor in 5 (6%). There was one radial nerve palsy secondary to the operative procedure. The reoperation rate, including the repair of nonunions, was 19%. We conclude that intramedullary Ender nail fixation is a relatively simple and quick procedure, especially for the multiply injured patient, that adequately stabilizes most humeral fractures, yielding overall good results.

[3-Dimensional computerized imaging in complex pelvic fractures].

3-dimensional computerized imaging is a relatively new radiologic modality. The transformation of bi-plane CT images into 3-dimensions, enables the physician to rotate the desired region to any viewing angle. In complex anatomic regions such as the pelvis, it offers better visualization of lesions, avoids having to rotate the patient, and reduces the need for X-rays and exposure to radiation. Our preliminary results with this modality in 3 cases of complex fractures of the pelvis are presented.

Urodynamic studies after intrathecal administration of baclofen and morphine in dogs.

The effects of intrathecally administered baclofen and morphine on the lower urinary tract dynamics of anesthetized dogs were investigated by means of cystometrogram and urethral pressure profile measurement. The experiments were performed prior to and 30, 60 and 90 minutes following intrathecal injection of either baclofen (0.03 mg./kg.), morphine (0.03 mg./kg.), or a mixture of the two (0.03 mg./kg. of each drug). Vesical pressure was significantly depressed after either baclofen (p less than 0.005) or morphine (p less than 0.005), while urethral pressure was decreased significantly only following baclofen (p less than 0.025). Administration of a baclofen/morphine admixture resulted in an additive reaction on the urethral pressure profile, compared with the changes brought about by each drug alone. Relaxation of the bladder and reduction in urethral resistance occurred 30 minutes post injection, increasing progressively after 60 and 90 minutes. The results demonstrated that baclofen, by its influence on cord neuron interaction, is capable of inhibiting the activity of the smooth muscle of the normal bladder and urethra, which in the case of the latter became more pronounced when both drugs were administered simultaneously by the intrathecal route.