Lee H. Riley

Ectopic Ossification Following Total Hip Replacement: Incidence And A Method Of Classification

A method to classify the degree of ectopic-bone formation about the hip following total hip arthroplasty revealed that 21 per cent of 100 consecutive patients treated by total hip arthroplasty had ectopic-bone formation about the hip of various degrees when reviewed six months following the operation. Ectopic-bone formation, however, did not seem to affect the functional result as judged by the Harris hip evaluation unless apparent bone ankylosis resulted.

Inhibition of TGF-β signaling in mesenchymal stem cells of subchondral bone attenuates osteoarthritis

Osteoarthritis is a highly prevalent and debilitating joint disorder. There is no effective medical therapy for the condition because of limited understanding of its pathogenesis. We show that transforming growth factor β1 (TGF-β1) is activated in subchondral bone in response to altered mechanical loading in an anterior cruciate ligament transection (ACLT) mouse model of osteoarthritis. TGF-β1 concentrations are also high in subchondral bone from humans with osteoarthritis. High concentrations of TGF-β1 induced formation of nestin-positive mesenchymal stem cell (MSC) clusters, leading to formation of marrow osteoid islets accompanied by high levels of angiogenesis. We found that transgenic expression of active TGF-β1 in osteoblastic cells induced osteoarthritis, whereas inhibition of TGF-β activity in subchondral bone attenuated the degeneration of articular cartilage. In particular, knockout of the TGF-β type II receptor (TβRII) in nestin-positive MSCs led to less development of osteoarthritis relative to wild-type mice after ACLT. Thus, high concentrations of active TGF-β1 in subchondral bone seem to initiate the pathological changes of osteoarthritis, and inhibition of this process could be a potential therapeutic approach to treating this disease.Osteoarthritis is a highly prevalent and debilitating joint disorder. There is no effective medical therapy for osteoarthritis due to limited understanding of osteoarthritis pathogenesis. We show that TGF–β1 is activated in the subchondral bone in response to altered mechanical loading in an anterior cruciate ligament transection (ACLT) osteoarthritis mouse model. TGF–β1 concentrations also increased in human osteoarthritis subchondral bone. High concentrations of TGF–β1 induced formation of nestin+ mesenchymal stem cell (MSC) clusters leading to aberrant bone formation accompanied by increased angiogenesis. Transgenic expression of active TGF–β1 in osteoblastic cells induced osteoarthritis. Inhibition of TGF–β activity in subchondral bone attenuated degeneration of osteoarthritis articular cartilage. Notably, knockout of the TGF–β type II receptor (TβRII) in nestin+ MSCs reduced development of osteoarthritis in ACLT mice. Thus, high concentrations of active TGF–β1 in the subchondral bone initiated the pathological changes of osteoarthritis, inhibition of which could be a potential therapeutic approach.

Joint-position Sense after Total Hip Replacement

Sixteen patients were studied prior to and after total hip replacement with an apparatus designed to eliminate all sensory cues to the perception of the position of the joint, except stimuli from the joint capsule and periarticular soft tissues. The detection of passive movement and its extent and t

Dysphagia after anterior cervical decompression and fusion: prevalence and risk factors from a longitudinal cohort study.

Study Design. Retrospective analysis of the incidence and prevalence of dysphagia after anterior cervical decompression and fusion (ACDF). Objectives. To examine the incidence and prevalence of dysphagia after ACDF, determine possible associated patient and procedural characteristics, and examine dysphagia’s impact on long-term health status and function. Summary of Background Data. Dysphagia is a common early complaint after ACDF, but the risk factors associated with its development are not understood. Methods. Telephone surveys (Cervical Spine Outcomes Questionnaire) and clinical assessments (Oswestry Neck Disability Scale and SF-36) were used to evaluate 454 patients who had undergone ACDF at one of 23 nationwide sites for individual and procedure characteristics that might contribute to dysphagia. Results. Of the 454 patients, 30% reported dysphagia at the 3-month assessment (incident cases). The incidence of new complaints of dysphagia at each follow-up point was 29.8%, 6.9%, and 6.6% at 3, 6, and 24 months, respectively. Dysphagia persisted at 6 and 24 months in 21.5% and 21.3% of patients, respectively. The risk of dysphagia increased with number of surgical vertebral levels at 3 months: 1 level, 42 of 212 (19.8%); 2 levels, 50 of 150 (33.3%); 3+ levels, 36 of 92 (39.1%). Patients reporting dysphagia at 3 months had a significantly higher self-reported disability and lower physical health status at subsequent assessments. Conclusion. Duration of preexisting pain and the number of vertebral levels involved in the surgical procedure appear to influence the likelihood of dysphagia after ACDF.

The thoracolumbar spine in Marfan syndrome.

We analyzed the prevalence, inheritance, progression, and functional implications of spinal deformity in Marfan syndrome using four different groups of patients. We studied 113 patients who had Marfan syndrome, eighty-two of whom were skeletally immature, in order to characterize the alignment and function of the spine. The patients were selected from a clinic that provides total care with no bias toward the presence of orthopaedic conditions. Scoliosis was identified in fifty-two of the eighty-two patients, and the prevalences for the sexes were equal. The thoracic portion of the curve was convex to the right in all but two patients. The mean kyphosis was greater than that in the general population. Five distinct sagittal profiles were identified on the basis of whether the thoracic kyphosis was within, greater than, or less than normal limits and whether the transition between the kyphosis and lordosis occurred at or caudad to the normal level or whether the curves were reversed. Spondylolisthesis was present in five patients (6 per cent), with a mean slip of 30 per cent. Fourteen pedigrees were studied in depth. There was no familial pattern of the scoliosis. A separate group of fifty-six patients with scoliosis, for whom serial follow-up radiographs were available, was studied for progression. Patients who had a curve of more than 30 degrees had mild progression, and those who had a curve of more than 50 degrees had marked progression (mean, 3 +/- 4 degrees per year). Pain and function of the back were studied in thirty patients who were thirty-five to forty-five years old; these patients were found to be more impaired than matched controls. The presence of scoliosis was associated with pain in the region of the curve in these patients.

Pelvic Fixation In Spine Surgery: Historical Overview, Indications, Biomechanical Relevance, And Current Techniques

F usions of the lumbosacral spine continue to be a challenging area in spine surgery. The complex local anatomy, unique biomechanical forces, and poor bone quality of the sacrum are just a few of the many reasons why fusions of the lumbosacral spine have been notoriously difficult to perform. The goals of this review were (1) to familiarize the reader with the complicated anatomy of the lumbosacral region, the specific pathological entities that involve this region, and the biomechanical forces that lead to high pseudarthrosis rates; (2) to discuss the various types of lumbosacral and spinopelvic implants and their respective advantages and disadvantages; (3) to review the most common clinical indications for lumbosacral and spinopelvic fusions; and (4) to emphasize that iliac screw placement is a safe and reproducible technique for achieving stable caudad pelvic fixation that minimizes the risk of pseudarthrosis at the lumbosacral junction. T he sacrum, which functions as the keystone that unites the two hemipelves, consists of five fused vertebrae with transverse processes that merge into a thick, continuous lateral mass. Its anteroposterior diameter tapers rapidly from 47 mm at S1 to 28 mm at S2 in women and from 50 to 31 mm in men1. For the most part, the sacrum has a cancellous osseous architecture, but areas of increased bone density are present in the sacral alae and particularly in the sacral promontory2. Therefore, it is best that pedicle screws be directed toward the midline. The sacrum is connected to each hemipelvis by the sacroiliac joint, which is the largest joint in the axial skeleton. The sacroiliac joint contains a synovial membrane but has minimal motion because of the matching interdigitating contours of the sacral and iliac bones and the strong interosseous, dorsal, ventral, and accessory ligaments3. It …

Higher electrical stimulus intensities are required to activate chronically compressed nerve roots: Implications for intraoperative electromyographic pedicle screw testing

Study Design. A comparison of the electrical thresholds required to evoke myogenic responses from direct stimulation of normal and chronically compressed nerve roots. Objective. To determine whether intraoperative electromyographic testing to confirm the integrity of instrumented pedicles should be performed at higher stimulus intensities in cases where there is preoperative lumbosacral radiculopathy. Summary of Background Data. Postoperative neurologic deficits may occur as a result of pedicle screw misplacement during spinal instrumentation. The failure to evoke myogenic responses from stimulation of pedicle holes and screws at intensities of 6‐8 mA is commonly used to exclude bony pedicular wall perforation. Methods. Direct nerve root stimulation was used to compare the stimulus thresholds of normal and compressed nerve roots in six patients with limb weakness from chronic lumbosacral radiculopathy. Results. The stimulus thresholds of chronically compressed nerve roots significantly exceeded those of normal nerve roots, indicating partial axonal loss (axonotmesis). In most cases, the direct stimulus thresholds of compressed nerve roots exceeded 10 mA. Conclusions. When instrumentation is placed at spinal levels where there is preexisting chronic lumbosacral radiculopathy, holes and screws may need to be stimulated at higher intensities to exclude pedicular perforation and prevent further iatrogenic nerve root injury.

Insurance status, geography, race, and ethnicity as predictors of anterior cervical spine surgery rates and in-hospital mortality: an examination of United States trends from 1992 to 2005.

Study Design. Retrospective cross-sectional study. Objective. To determine the role of race, insurance status, and geographic location on US anterior cervical spine surgery rates and in-hospital mortality between 1992 and 2005. Summary of Background Data. Previous investigation indicates that anterior cervical spine surgery has been increasingly used in the management of degenerative cervical spine disease throughout the 1990s. Significant predictors of health outcomes, including race, ethnicity, geography, and insurance coverage have yet to be investigated in detail for these procedures. Methods. Cases of anterior cervical spine surgery were identified from the Nationwide Inpatient Sample. The US population counts were taken from the Current Population Survey. Multivariate regression models were employed to describe national rates of anterior cervical spine surgery and model the odds of death among admissions for anterior cervical spine surgery. All models incorporated adjustment for hospital sample clustering, age, and comorbidity status. Results. Based on an analysis of a total 100,286,482 hospital discharge records, an estimated 965,600 anterior cervical spine procedures were performed between 1992 and 2005 in the United States. During this period, rates of surgery increased by 289%. Though adjusted rates of surgery were lowest among minority populations, disparities decreased with time. The mean age of patients, as well as the average preoperative comorbidity status, increased with time. The odds of mortality did not significantly increase between 1992 and 2005. Odds of in-hospital death were greatest in among black patients (P < 0.001) and lowest in Southern states (P < 0.001) and patients with private insurance (P < 0.001). Conclusion. With the recent rise of anterior cervical spine procedures in the United States, substantial variation in the delivery of surgical care exists along a number of demographic factors. A detailed investigation of variation in surgical decision-making algorithms among spine specialists, as well as a determination of differences among patient populations in attitudes toward surgery, may help elucidate the trends observed in this study.

Postoperative dysphagia in anterior cervical spine surgery

Study Design. Systematic review. Objective. To determine the incidence and prevalence and identify effective recommendations to minimize the incidence and prevalence of postoperative dysphagia after anterior cervical surgery. Summary of Background Data. The reported incidence and prevalence of postoperative dysphagia and risk factors associated with its development varies widely in the literature. Methods. A systematic review of the English-language literature was undertaken for articles published between January 1990 and December 2008. Electronic databases and reference lists of key articles were searched to identify published studies examining the incidence and prevalence of dysphagia after anterior cervical spine surgery. Two independent reviewers assessed the strength of literature using the Grading of Recommendations Assessment, Development, and Evaluation criteria, assessing quality, quantity, and consistency of results. Disagreements were resolved by consensus. Results. A total of 126 articles were initially screened, and 17 ultimately met the predetermined inclusion criteria. The rates of dysphagia found in the literature varied widely. Rates declined after surgery, but plateau at 1 year at a range of 13% to 21%. Risk factors identified were multilevel surgery and female sex. Specific preventive measures were not identified. Conclusion. A better understanding of dysphagia will require the development of better outcome measures.

Patient activation and adherence to physical therapy in persons undergoing spine surgery.

Study Design. Prospective longitudinal study. Objective. To determine the association between baseline patient activation and participation in postoperative physical therapy in a cohort of individuals after lumbar spine surgery. Summary of Background Data. The Patient Activation Measure is a recently developed tool to assess patient activation. Patient activation is defined as an individual’s propensity to engage in adaptive health behavior that may, in turn, lead to improved patient outcomes. It has not previously been used in spine research. Methods. We assessed baseline patient activation levels in individuals presenting for surgery of the lumbar spine via the Patient Activation Measure. Differences in patient characteristics across patient-activation quartiles were assessed using analysis of variance. After surgery, we assessed attendance (self-reported weekly) and engagement in physical therapy (at the last visit, using the Hopkins Rehabilitation Engagement Rating Scale) and determined the ratio of sessions attended to sessions prescribed. The influence of baseline patient activation, in the setting of other patient characteristics, to predict attendance and engagement with physical therapy was examined using linear regression methods. Results. Scores on the Patient Activation Measure were positively correlated with participation (r = 0.53) and engagement (r = 0.75) in physical therapy. Individuals with low activation were more likely to report low self-efficacy for physical therapy, low hope, and external locus of control compared with those with high activation. Conclusion. Increased patient activation is associated with improved adherence with physical therapy as reflected in attendance and engagement.