A model is developed of the human lower extremity to study how changes in musculoskeletal geometry and musculotendon parameters affect muscle force and its moment about the joints. The lines of action of 43 musculotendon actuators were defined based on their anatomical relationships to three-dimensional bone surface representations. A model for each actuator was formulated to compute its isometric force-length relation. The kinematics of the lower extremity were defined by modeling the hip, knee, ankle, subtalar, and metatarsophalangeal joints. Thus, the force and joint moment that each musculotendon actuator develops can be computed for any body position. The joint moments calculated with the model compare well with experimentally measured isometric joint moments. A graphical interface to the model has also been developed. It allows the user to visualize the musculoskeletal geometry and to manipulate the model parameters to study the biomechanical consequences of orthopaedic surgical procedures. For example, tendon transfer and lengthening procedures can be simulated by adjusting the model parameters according to various surgical techniques. Results of the simulated surgeries can be analyzed quickly in terms of postsurgery muscle forces and other biomechanical variables. >

An interactive graphics-based model of the lower extremity to study orthopaedic surgical procedures

Study design This study is a retrospective review of the initial enrollment data from a prospective multicentered study of adult spinal deformity. Objectives The purpose of this study is to correlate radiographic measures of deformity with patient-based outcome measures in adult scoliosis. Summary of background data Prior studies of adult scoliosis have attempted to correlate radiographic appearance and clinical symptoms, but it has proven difficult to predict health status based on radiographic measures of deformity alone. The ability to correlate radiographic measures of deformity with symptoms would be useful for decision-making and surgical planning. Methods The study correlates radiographic measures of deformity with scores on the Short Form-12, Scoliosis Research Society-29, and Oswestry profiles. Radiographic evaluation was performed according to an established positioning protocol for anteroposterior and lateral 36-inch standing radiographs. Radiographic parameters studied were curve type, curve location, curve magnitude, coronal balance, sagittal balance, apical rotation, and rotatory subluxation. Results The 298 patients studied include 172 with no prior surgery and 126 who had undergone prior spine fusion. Positive sagittal balance was the most reliable predictor of clinical symptoms in both patient groups. Thoracolumbar and lumbar curves generated less favorable scores than thoracic curves in both patient groups. Significant coronal imbalance of greater than 4 cm was associated with deterioration in pain and function scores for unoperated patients but not in patients with previous surgery. Conclusions This study suggests that restoration of a more normal sagittal balance is the critical goal for any reconstructive spine surgery. The study suggests that magnitude of coronal deformity and extent of coronal correction are less critical parameters.

Correlation of radiographic parameters and clinical symptoms in adult scoliosis

https://www.ipd.gu.se/digitalAssets/1252/1252566_Artikel_sept_Aina_Lancet_2_.pdf

Adolescent idiopathic scoliosis.

A spine distraction implant alleviates pain associated with spinal stenosis and facet arthropathy by expanding the volume in the spine canal and/or neural foramen. The implant provides a spinal extension stop while allowing freedom of spinal flexion.

Spine distraction implant and method

U Because skeletal dysplasias are primary disorders of bone, they have not been commonly understood as neurosurgical diseases. Nevertheless, neurosurgical complications are commonly encountered in many cases of dysplasia syndromes. The authors present two cases of skeletal dysplasia that caused overt instability of the cervical spine. One patient with a diagnosis of Gorham disease of the cervical spine was treated with prolonged fixation in a halo brace after an initial attempt at instrumentation with a posterior occiput‐C4 fusion. The other patient, who at birth was identified to have camptomelic dysplasia, has been treated conservatively from the outset. Although these two patients presented with different disorders—in one patient adequate mature bone never formed and in the other patient progressive bone loss became apparent after a seemingly normal initial development—these cases demonstrate unequivocally that surgical options for fusion are ultimately limited by the quality of the underlying bone. In patients in whom the bone itself is inadequate for use as a substrate for fusion, there are currently limited treatment options. Future improvements in our understanding of chondrogenesis and ossification may lead to the design of superior methods of encouraging fusion in these patients; however, at the present time, long-term maintenance in a halo brace may, in fact, be the only treatment.

/pdf/report-of-two-cases-and-review-of-the-literature-12jmr5r1y4.pdf

Report of two cases and review of the literature

A total of 295 patients treated with the Boston bracing system with follow-up of at least 1 year after completion of bracing are reviewed. Pre-brace curves ranged from 20-59 degrees Cobb. Mean age at brace initiation was 13.2 years with a mean treatment time of 2.9 years and mean follow-up of 1.4 years. Mean best in-brace correction averaged 50% with correction averaging 23% at the initiation of weaning from the brace. By the time of brace discontinuance, average curve correction was 15%. At follow-up, average correction was 11%. A comparison of follow-up with pre-brace values of major curves showed that 49% were unchanged +/- 5 degree, 39% achieved final correction of 5-15 degrees, 4% achieved final correction of 15 degrees or more, 4% of patients lost 5-15 degrees, and 3% lost more than 15 degrees by the time of follow-up. Eleven percent of patients underwent surgery during the period of bracing; 1% had surgery during follow-up period. Correction and control of major curves with apexes below T8 and above L2 were best. A strong correlation between best, or initial in-brace correction, and follow-up correction was noted. Young age at the initiation of bracing and higher degrees of pre-brace curvature increased the incidence of surgery. Those curves that had corrected most at the end of bracing were most at risk for loss of correction after bracing. Partial compliance with brace wear appeared as effective as full-time wear. Boston braces without superstructure appeared to be as effective as braces with superstructure for curves with apexes below T7.

The Boston bracing system for idiopathic scoliosis. Follow-up results in 295 patients.

We retrospectively reviewed the results of operative treatment of chronic Monteggia lesions (Bado type I or the equivalent) with anterior radiocapitellar dislocation in seven patients. The mean age at the time of the reconstruction was six years and nine months (range, eleven months to twelve years), and the mean time from the injury to the operation was twelve months (range, five weeks to thirty-nine months). The mean duration of follow-up was four years and six months (range, two years to eleven years and three months). There were fourteen complications, including malunion of the ulnar shaft in one patient; residual radiocapitellar subluxation in two patients (one anterior and one posterolateral); radiocapitellar dislocation (dynamic anterior subluxation of the radial head in supination) in one patient; transient ulnar-nerve palsy in three patients (with residual weakness in two); partial laceration of the radial nerve in one patient; loss of the fixation in two patients; and non-union of the ulnar osteotomy site, compartment syndrome, conversion reaction, and possible fibrous synostosis of the forearm in one patient each. The patients lost a mean of 36 degrees of pronation and a mean of 27 degrees of supination of the forearm compared with the contralateral, uninjured extremity. Two patients demonstrated a loss of flexion of the elbow of 8 and 13 degrees and three had a loss of extension (mean, 15 degrees) compared with the contralateral side. There were three good, two fair, and two poor results.

Chronic Monteggia Lesions in Children.: Complications and Results of Reconstruction*

We retrospectively reviewed the magnetic resonance imaging studies that had been made for ninety-five patients who had idiopathic scoliosis. We wished to determine if we could identify any criteria that should be met before these studies are performed. The study group included thirty-one male patients and sixty-four female patients. The average age at the time of the imaging study was thirteen years (range, one to twenty-eight years). The average curve was 41 degrees (range, 11 to 95 degrees). Fourteen patients were seen to have an intraspinal abnormality on the imaging study: twelve had a syrinx, one had a syrinx and an astrocytoma of the spinal cord, and one had dural ectasia. Five of the eight patients who were less than eleven years old and who had a left thoracic curve had an intraspinal abnormality on the imaging study, but this combination of factors did not indicate the need for operative intervention. Four of the intraspinal abnormalities in the fourteen patients necessitated neurosurgical intervention; if the criteria for obtaining the imaging study had been restricted to neck pain and headache--particularly with exertion--and neurological findings such as ataxia, weakness, and a cavus foot, these abnormalities would have been diagnosed.

Childhood scoliosis: clinical indications for magnetic resonance imaging.

Thirty-two adolescent girls braced for late onset idiopathic scoliosis at Children's Hospital, Boston were compared with thirty-two untreated girls from Our Lady's Hospital for Sick Children, Dublin, Ireland paired on the basis of curve size and site and age at diagnosis. All were Risser 0 at diagnosis. Study period for the braced group was from brace initiation to part-time brace wearing and, for the controls, from diagnosis to last review. There was no statistically significant difference between the groups on any parameter of curve progression. This study raises questions about the efficacy of spinal orthoses in modifying the natural history of late-onset idiopathic scoliosis and removes the ethical problems inherent in a prospective trial in which the only treatment permitted to the control group is surgery.

John E. Hall

Papers

The Boston bracing system for idiopathic scoliosis. Follow-up results in 295 patients.

Chronic Monteggia Lesions in Children.: Complications and Results of Reconstruction*

Childhood scoliosis: clinical indications for magnetic resonance imaging.

A Statistical Comparison Between Natural History of Idiopathic Scoliosis and Brace Treatment in Skeletally Immature Adolescent Girls

Scoliosis surgery in adults.