Prospective clinical study on the effect of total hip replacement surgery (THR) on low back pain (LBP) in patients with severe hip osteoarthritis. To assess the affect of THR on LBP. Hip osteoarthritis causes abnormal gait and spinal sagittal alignment and is associated with LBP. All consecutive adults scheduled for THR in our department due to severe hip osteoarthritis were assessed by an independent investigator before surgery and 3 months and 2 years post-THR. The Harris Hip Score and the Oswestry scores were used to evaluate hip- and spine-related symptoms, respectively, as were visual analogue scales (VAS) and sagittal spinal radiographs. Twenty-five patients (10 males; age range, 32-84 years) were evaluated. Both spinal and hip pain and function were significantly better following THR. The mean preoperative LBP VAS score of 5.04 was 3.68 after THR (P = 0.006). The mean preoperative Oswestry score of 36.72 was 24.08 after THR (P = 0.0011). Clinical improvement was maintained and enhanced at the 2-year follow-up. The mean hip pain VAS score was 7.08 before THR and 2.52 after THR (P < 0.01). The mean Harris Hip Score was 45.74 before and 81.8 after surgery (P < 0.01). There were no changes in the radiographic measurements. Both LBP and spinal function were improved following THR. This study demonstrates the clinical benefits of THR on back pain and is the first to clinically validate hip-spine syndrome as hypothesized by Offierski and MacNab in 1983.

To prospectively evaluate use of bone scintigraphy with single photon emission computed tomography (SPECT) for identification of patients with low back pain who would benefit from facet joint injections. The protocol was reviewed and approved by the institutional review board. All patients provided informed consent. Forty-seven patients (23 men and 24 women) with low back pain, who were scheduled for facet joint injections, were prospectively enrolled and randomized into groups A and B (mean ages, 43.3 and 44.2 years, respectively) with a group A-group B ratio of 2:1. Group A patients underwent bone scintigraphy with SPECT prior to injection. Group A patients with bone scans positive for facet joint abnormalities received injections at the levels where abnormalities were identified on the scan (group A1). Group A patients with negative scans (group A2) received injections at the levels that were decided as in group B. Group B patients received injections at the levels indicated by the referring physician and did not undergo bone scintigraphy. All patients completed a pain and function questionnaire before injection and at 1, 3, and 6 months afterward. The change in the American Academy of Orthopaedic Surgeons pain scores after 1, 3, and 6 months compared with baseline scores was analyzed with analysis of variance and post hoc Bonferroni multiple-comparison tests between groups. Cost analysis was performed. The change in the pain score at 1 month was significantly higher (P < .004) in group A1 than it was in the other two groups. In group A1, 13 of 15 patients had improvement in pain score of greater than 1 standard deviation at 1 month, whereas improvement occurred in only two of 16 patients in group A2 and five of 16 patients in group B. In patients with positive scans, the number of facets treated with injection was decreased from 60, which was the number originally indicated by the referring physician, to 27. The Medicare cost was reduced from $2191 per patient to $1865 with the use of SPECT. Bone scintigraphy with SPECT can help identify patients with low back pain who would benefit from facet joint injections.

Acetabular redirection osteotomy can be used to relieve pain, improve function, and extend the life of dysplastic hip joints. To understand better the factors that may determine the acetabular reorientation that minimizes pressures, joint contact pressures were calculated by computer assisted methods in 70 dysplastic and 12 normal hips (82 patients). Calculated pressures were consistent with pressures estimated and measured by other investigators. Contact areas were 26% smaller, and contact pressures were 23% higher, in the dysplastic hips compared with the normal hips. When the acetabula were reoriented to minimize contact pressures for an activity such as the midstance phase of gait, then contact pressures were elevated for dissimilar activities such as stair ascent. Contact pressures in the dysplastic hips were reduced when the acetabula were rotated in the frontal plane to increase lateral coverage or rotated in the sagittal plane to increase anterior coverage. In most of the dysplastic hips, contact pressures were reduced twice as much when the acetabulum was rotated in the frontal and the sagittal planes. Computer assisted methods to quantify joint contact pressures can be used to assess potential candidates for reconstruction, plan acetabular redirection surgery, and possibly may improve the long term success of acetabular redirection osteotomy.

Prospective, observational. Quantify the changes in intervertebral motion adjacent to cervical arthrodesis over time. One of the frequently acknowledged sequelae following anterior cervical fusion is the development of adjacent segment disease. It has been argued that a spine fusion transfers stress to adjacent levels and results in increased compensatory motion. However, there are conflicting reports as to whether this actually occurs, and most of these are in vitro or retrospective clinical studies. Patients undergoing anterior cervical discectomy and fusion underwent a preoperative dynamic fluoroscopic study, followed by imaging at regular intervals after surgery. Imaging data were analyzed by a validated software system. Relative motion between adjacent vertebrae was then calculated, and changes in motion cephalad to the fusion followed over time. Twenty-one patients were analyzed. Mean follow-up was 13 months (10–22 months). Intervertebral motion adjacent to the fusion changed by more than 4° in 4 of the 21 patients. However, on average, there was no difference between preoperative and postoperative motion for shear, flexion–extension, or vertical displacement at the anterior or posterior disc space. Although there was some individual variation, at a mean of 13 months following surgery, there was no significant change in the average junctional intervertebral motion. If fusion is going to affect adjacent motion, it appears that this does not consistently occur in the first 1 to 2 years following surgery. Additionally, there was no observable relationship between motion and development of degenerative changes during this time.

Twenty-seven paired human cadaveric knee specimens were used to determine the effect of surgical technique and various interference screw parameters on the pullout strength of patellar tendon femoral bone blocks. The study compared the fixation strength of endoscop ically inserted and conventional "rear-entry" screws of different diameters and lengths. In all tests the most frequent mode of failure was bone block pullout from the interference screw. There was no significant differ ence in fixation strength between 9-mm diameter screws inserted through a conventional rear-entry tech nique and 7-mm diameter screws inserted through an endoscopic technique. There was no significant effect of screw length on fixation strength. The pullout force for 20-mm long screws increased on average 120% when 7-mm diameter screws were compared with 5.5- mm diameter screws. There was no significant effect of increased screw core diameter on fixation strength. There was a weak positive correlation ( r ² = 0.45) between screw insertion torque and pullout force. Our measured mean pullout force for the 7-mm endoscopi cally inserted screws of 362 ± 198 N represents 20.1 % of the failure load of the normal young adult anterior cruciate ligament. Our data indicate that properly in serted 7-mm diameter endoscopic interference screws can provide fixation strengths of patellar tendon ante rior cruciate ligament grafts equivalent to those of con ventional 9-mm diameter rear-entry, outside-in screws.