Sex-based differences in neck selectivity in total hip arthroplasty using a modular femoral neck system.

BACKGROUND: Dislocation is a major complication of total hip arthroplasty (THA). The modular femoral neck system provides practical advantages by allowing adjustment of neck version and length in the presence of intraoperative instability. Anatomical studies have identified morphological differences in the hip joint between men and women. Despite sex-based differences in hip morphology, it remains unclear whether such differences affect neck selectivity in THA using a modular neck system and whether this approach achieves anatomical reconstruction, thereby reducing complications such as dislocation. This study aimed to investigate gender differences in neck selectivity in THA with the modular neck system and assess the clinical impact of the modular neck system. METHODS: A total of 163 THAs using a modular neck system were included in this study. Data on the type of modular neck and intraoperative range of motion (ROM) were retrieved from patient records. Pre- and post-operative leg length differences (LLD) were examined as part of the radiographic assessment. Dislocation was investigated as a postoperative complication. RESULTS: Neck selectivity did not significantly differ between men and women. The comparison of pre- and post-operative LLD revealed a tendency for varus necks to improve LLD more than version-controlled necks. Furthermore, no significant correlation was found between intraoperative ROM and neck selectivity, or postoperative dislocation and neck selectivity. CONCLUSIONS: This study on THA with a modular neck system provided valuable insights into sex-based differences in neck selectivity and highlighted the potential benefits of the modular neck system in addressing LLD and preventing postoperative dislocation.

Asymmetrical pedicle subtraction osteotomy for rigid degenerative lumbar kyphoscoliosis.

STUDY DESIGN: A prospectively study. OBJECTIVE: Our objective was to clarify the safety and efficacy of asymmetrical pedicle subtraction osteotomy (PSO) in the treatment of severe adult lumbar deformities prospectively. SUMMARY OF BACKGROUND DATA: Vertebral wedge osteotomy provides good correction of kyphosis but has rarely been applied to degenerative lumbar kyphoscoliosis. METHODS: A total of 14 patients who had undergone corrective osteotomy were enrolled. The average age at PSO was 67 years (range, 45-76 yr). The minimum follow-up was 2 years. Patient questionnaires were administered prospectively. Radiographical parameters including sagittal and coronal balance were analyzed. RESULTS: Average operative time was 310 minutes (range, 254-375 min). Average blood loss was 1090 mL (range, 700-2900 mL).Mean preoperative lumbar lordosis improved from -3° to 42° at the final follow-up, and sagittal balance improved from 12 to 3 cm, respectively. Mean lumbar scoliosis improved from 40° to 12°, and coronal offset improved from 3 to 1 cm, respectively. There was also statistically significant improvement from preoperative to final evaluation in all clinical domains. There were 4 complications: 1 dural tear, 2 hook dislodgements at the cephalad side requiring revision instrumentation, and 1 rod breakage not requiring surgical intervention. Overall, all 14 patients were satisfied with their surgical management and would choose to repeat the procedure. CONCLUSION: Our data suggest that the surgical procedure of asymmetrical PSO is to correct the scoliosis, to restore the lumbar lordosis by way of convex-sided posterolateral wedge osteotomy, and may go a long way toward solving the problems of rigid lumbar degenerative kyphoscoliosis.

Incidence of osteonecrosis associated with corticosteroid therapy among different underlying diseases: prospective MRI study.

OBJECTIVES: The purpose of this study was to clarify the incidence of (CS)-associated osteonecrosis among different underlying diseases and to evaluate the risk factors for steroid-associated osteonecrosis in a prospective MRI study. METHODS: We prospectively used MRI to study 337 eligible underlying disease patients requiring CS therapy and succeeded in examining 1199 joints (hips and knees) in 302 patients with MRI for at least 1 year starting immediately after the onset of CS therapy (1-year follow-up rate of 90%). The underlying diseases included SLE in 687 joints (173 patients) and a variety of other rheumatological disorders in 512 joints (129 patients). RESULTS: The incidence of osteonecrosis was significantly higher in SLE patients than in non-SLE patients (37 vs 21%, P = 0.001). Logistic regression analysis revealed that adolescent and adult patients had a significantly higher risk of osteonecrosis compared with paediatric patients [odds ratio (OR) = 13.2], that high daily CS dosage (>40 mg/day) entailed a significantly higher risk of osteonecrosis compared with the dosage of <40 mg/day (OR = 4.2), that SLE patients had a significantly higher risk of osteonecrosis compared with non-SLE patients (OR = 2.6) and that male patients had a significantly higher risk of osteonecrosis compared with female patients (OR = 1.6). CONCLUSION: These findings suggest that the incidence of CS-associated osteonecrosis varies among different underlying diseases.

Subsequent vertebral fractures following spinal fusion surgery for degenerative lumbar disease: a mean ten-year follow-up.

STUDY DESIGN: Case-control study. OBJECTIVE: To assess the long-term prevalence of vertebral fractures after lumbar spinal fusion with instrumentation. SUMMARY OF BACKGROUND DATA: The incidence of the adjacent and the nonadjacent, remote level subsequent vertebral fractures after lumbar spinal fusion is not well described in the literature. METHODS: The study is a retrospective analysis of 100 consecutive patients of 55 years of age or older with spinal fusion for degenerative diseases between L1 and S1, and instrumentation for less than 4 segments. Patients with prevalent vertebral fractures defined at the time of surgery, or patients with secondary causes of osteoporosis were excluded. Mean follow-up period was 10.2 years (range, 7-14 years). Acute vertebral fractures were determined by magnetic resonance imaging and lateral spine radiographs. RESULTS: Acute vertebral fractures were determined in 20 vertebrae in 14 (24%) of the 59 female patients, whereas 1 male patient (2%) had 1 vertebral fracture during the follow-up period. Eighteen of the 21 fractures occurred within 2 years of the spinal instrumentation surgery. Regarding time to fracture occurrence after surgery, adjacent level fractures occurred within 8 months, and remote level fractures occurred between 8 and 22 months after surgery. CONCLUSION: Postmenopausal female patients who underwent lumbar spinal instrumentation surgery were susceptible to develop subsequent vertebral fractures within 2 years after surgery. The greater the number of spinal segments between the fracture and the instrumentation was, the longer the time after surgery.

Facet joint orientation difference between cephalad and caudad portions: a possible cause of degenerative spondylolisthesis.

STUDY DESIGN: A case-control study. OBJECTIVE.: To measure the orientation of the facet joints at both cephalad and caudad portions and to compare them between patients with degenerative spondylolisthesis (DS) and patients with lumbar spinal stenosis (LSS, controls). SUMMARY OF BACKGROUND DATA: Several radiologic studies have indicated a correlation between DS and an increased sagittal orientation of the facet joints. However, the orientation of the facet joints have only been measured on 1 axial cut of computed tomography scans and magnetic resonance imaging. METHODS: Thirty-two patients with DS only at the L4-L5 level were assigned to group-1, and 28 patients with LSS without DS were assigned to group-2. Two computed tomography scans for the cephalad and caudad portions of the facet joint were made for L3-L4 and L4-L5 levels, respectively. Delta facet angle was defined as facet angle (cephalad)-facet angle (caudad). RESULTS: Facet angles of the cephalad portion were more sagittally oriented (P < 0.001) than those of the caudad portion in group-1. The mean facet angle of the cephalad portion was 72 degrees and that of the caudad portion was 57 degrees at L4-L5. The mean facet angle of the cephalad portion at L4-L5 was greater (P = 0.001) in group-1 (72 degrees ) than in group-2 (62 degrees ). Delta facet angles were significantly greater in group-1 than in group-2. Mean delta facet angle was 15 degrees in group-1 and 2 degrees in group-2 at L4-L5 (P < 0.001), and 4 degrees and 0 degrees , respectively, at L3-L4 (P = 0.046). CONCLUSION: In this study, we confirmed that the cephalad portion of the facet joints were more sagittally oriented and that the caudad portion of the facet joints were more coronally oriented in patients with DS. These findings were observed not only at L4-L5 but also at the uninvolved L3-L4 level in patients with DS at the L4-L5 level.

Transpedicular hydroxyapatite grafting with indirect reduction for thoracolumbar burst fractures with neurological deficit: A prospective study.

BACKGROUND: The major problem after posterior correction and instrumentation in the treatment of thoracolumbar burst fractures is failure to support the anterior spinal column leading to loss of correction of kyphosis and hardware breakage. We conducted a prospective consecutive series to evaluate the outcome of the management of acute thoracolumbar burst fractures by transpedicular hydroxyapatite (HA) grafting following indirect reduction and pedicle screw fixation. MATERIALS AND METHODS: Eighteen consecutive patients who had thoracolumbar burst fractures and associated incomplete neurological deficit were operatively treated within four days of admission. Following indirect reduction and pedicle screw fixation, transpedicular intracorporeal HA grafting to the fractured vertebrae was performed. Mean operative time was 125 min and mean blood loss was 150 ml. Their implants were removed within one year and were prospectively followed for at least two years. RESULTS: The neurological function of all 18 patients improved by at least one ASIA grade, with nine (50%) patients demonstrating complete neurological recovery. Sagittal alignment was improved from a mean preoperative kyphosis of 17°to -2°(lordosis) by operation, but was found to have slightly deteriorated to 1° at final followup observation. The CT images demonstrated a mean spinal canal narrowing preoperatively, immediate postoperative and at final followup of 60%, 22% and 11%, respectively. There were no instances of hardware failure. No patient reported severe pain or needed daily dosages of analgesics at the final followup. The two-year postoperative MRI demonstrated an increase of one grade in disc degeneration (n = 17) at the disc above and in 11 patients below the fractured vertebra. At the final followup, flexion-extension radiographs revealed that a median range of motion was 4, 6 and 34 degrees at the cranial segment of the fractured vertebra, caudal segment and L1-S1, respectively. Bone formation by osteoconduction in HA granules was unclear, but final radiographs showed healed fractures. CONCLUSIONS: Posterior indirect reduction, transpedicular HA grafting and pedicle screw fixation could prevent the development of kyphosis and should lead to reliable neurological improvement in patients with incomplete neurological deficit. This technique does not require fusion to a segment, thereby preserves thoracolumbar motion.

Changes in vertebral wedging rate between supine and standing position and its association with back pain: a prospective study in patients with osteoporotic vertebral compression fractures.

STUDY DESIGN: Prospective consecutive series. OBJECTIVE: To analyze supine and standing radiographs and the association of back pain using subjective pain criteria. SUMMARY OF BACKGROUND DATA: It has been considered that there is little correlation between the degree of collapse of the vertebral body and the level of pain. In previous studies, however, measurements have only been based on supine radiographs. Although there were 2 authors who reported the results of supine lateral and standing lateral radiographs in patients with thoracolumbar vertebral fractures, as far as we know, there has not been any detailed report concerning the correlation between radiologic findings using supine and standing lateral radiographs and back pain. METHODS: We examined 100 consecutively treated patients, prospectively. Back pain and the supine and standing radiographs were assessed 1 month after injury. Changes in vertebral wedging rate (WR) from supine to standing position (Delta WR) was reported by the following equation: Delta WR = WR(standing)-WR(supine). RESULTS: The median age of the cohort was 75 years (range, 60-89 years). The median VAS of back pain at supine position, at standing position, and when standing erect was 13, 33, and 41, respectively. The median wedging rate on the supine and standing radiographs were 28% and 37%, respectively (P < 0.001). There was a significant correlation between Delta WR and back pain when standing erect (r = 0.79, P < 0.001). CONCLUSION: Changes in vertebral wedging rate between supine and standing position and its association with back pain may give a clue to the pathogenesis of pain from osteoporotic thoracolumbar vertebral compression fractures.

Automatic measurement of polyethylene modification in metal-backed artificial hip joints using three-dimensional CT.

A new method has been developed for automatic measurement of polyethylene linear modification using three-dimensional CT in total hip arthroplasty (THA) and bipolar hemiarthroplasty (BHP). We obtained a three-dimensional digital image of the metal components by widening the maximum window width, adjusting the proper cutoff threshold level, and removing the metal artifact. The centric coordinates of both the metal-backed cup and the femoral head were calculated from this image. Modification was defined as a change in distance between those two points from their original interval. Phantom studies of the accuracy and reproducibility of the method indicated that the average error ranged from 0.02 to 0.12 mm and the standard deviation ranged from 0.01 to 0.05 mm. Clinical in vivo measurement was performed without error of computer software on 19 hips in which modification of highly cross-linked polyethylene components was significantly large.