Klane K. White

Intramuscular and blood pressures in legs positioned in the hemilithotomy position : clarification of risk factors for well-leg acute compartment syndrome.

Background: Acute compartment syndrome has been widely reported in legs positioned in the lithotomy position for prolonged general surgical, urologic, and gynecologic procedures. The orthopaedic literature also contains reports of this complication in legs positioned on a fracture table in the hemilithotomy position. The purpose of this study was to identify the risk factors for development of acute compartment syndrome resulting from this type of leg positioning. Methods: Eight healthy volunteers were positioned on a fracture table. Intramuscular pressures were continuously measured with a slit catheter in all four compartments of the left leg with the subject supine, in the hemilithotomy position with the calf supported, and in the hemilithotomy position with the heel supported but the calf free. Blood pressure was measured intermittently with use of automated pressure cuffs. Results: Changing from the supine to the calf-supported position significantly increased the intramuscular pressure in the anterior compartment (from 11.6 to 19.4 mm Hg) and in the lateral compartment (from 13.0 to 25.8 mm Hg). Changing from the calf-supported to the heel-supported position significantly decreased intramuscular pressure in the anterior, lateral, and posterior compartments (to 2.8, 3.4, and 1.9 mm Hg, respectively). The mean diastolic blood pressure in the ankle averaged 63.9 mm Hg in the supine position, which significantly decreased to 34.6 mm Hg in the calf-supported position. Changing to the heel-supported position had no significant effect on the diastolic blood pressure in the ankle (mean, 32.8 mm Hg). The mean difference between intramuscular pressure and diastolic blood pressure in the supine position was approximately 50 mm Hg in each of the four compartments. This mean difference significantly decreased to <20 mm Hg in the calf-supported position and then, when the leg was moved into the heel-supported position, significantly increased to approximately 30 mm Hg in all compartments. Conclusions: The combination of increased intramuscular pressure due to external compression from the calf support and decreased perfusion pressure due to the elevated position causes a significant decrease in the difference between the diastolic blood pressure and the intramuscular pressure when the leg is placed in the hemilithotomy position in a well-leg holder on a fracture table. Combined with a prolonged surgical time, this position may cause an acute compartment syndrome of the well leg. Leaving the calf free, instead of using a standard well-leg holder, increases the difference between the diastolic blood pressure and the intramuscular pressure and may decrease the risk of acute compartment syndrome.

Orthopaedic aspects of mucopolysaccharidoses

Skeletal abnormalities are an early and prominent feature of most mucopolysaccharide (MPS) disorders, with the degree of skeletal involvement varying between and within MPS subtypes. Most patients exhibit a constellation of radiographic abnormalities known as dysostosis multiplex, consisting of abnormally shaped vertebrae and ribs, enlarged skull, spatulate ribs, hypoplastic epiphyses, thickened diaphyses and bullet-shaped metacarpals. Thoracolumbar kyphosis or the gibbus deformity is often a key diagnostic clue. Also common are hip dysplasia, genu valgum and, later in the course of the disease, spinal cord compression, which can be life-threatening. Short stature is ubiquitous. Treatment of skeletal manifestations usually involves surgical intervention. All patients with MPS should be considered at high risk for surgical intervention requiring anaesthesia because of airway and cardiac disease manifestations. Regular imaging of the cervical, thoracic and lumbar spine, the hips and the lower extremities is recommended for patients with MPS.

EMG power spectra of intercollegiate athletes and anterior cruciate ligament injury risk in females

PURPOSE Females have a disproportionately high incidence of anterior cruciate ligament (ACL) injuries compared with males in analogous sports. Although the pathogenesis of this higher frequency has not been elucidated, gender differences in neuromuscular control of the knee may play an important role. This study evaluates EMG power spectra of the quadriceps and hamstring muscles during dynamic, fatiguing exercise to examine differences between male and female intercollegiate athletes. METHODS Fifty-one collegiate basketball and soccer players (25 female, 26 male) were studied. Maximum voluntary contraction (MVC) was determined for knee flexion and extension. Three consecutive 2-min bouts of isokinetic knee flexion and extension exercise were performed at 40% MVC. EMG activity in the biceps femoris and vastus medialis obliquus was recorded using bipolar surface electrodes. RESULTS MVC normalized to body weight was significantly greater in males than in females for the quadriceps (P< 0.01). Quadriceps coactivation ratios were significantly higher in females than in males during knee flexion exercises (P< 0.01). CONCLUSIONS This study demonstrates differences in the EMG power spectra for females when compared with a matched group of males. Increased quadriceps coactivation in females may increase anterior tibial loads under dynamic conditions, thus placing the ACL at higher risk for injury in the female athlete.

Spinal involvement in mucopolysaccharidosis IVA (Morquio-Brailsford or Morquio A syndrome): presentation, diagnosis and management

Mucopolysaccharidosis IVA (MPS IVA), also known as Morquio-Brailsford or Morquio A syndrome, is a lysosomal storage disorder caused by a deficiency of the enzyme N-acetyl-galactosamine-6-sulphate sulphatase (GALNS). MPS IVA is multisystemic but manifests primarily as a progressive skeletal dysplasia. Spinal involvement is a major cause of morbidity and mortality in MPS IVA. Early diagnosis and timely treatment of problems involving the spine are critical in preventing or arresting neurological deterioration and loss of function. This review details the spinal manifestations of MPS IVA and describes the tools used to diagnose and monitor spinal involvement. The relative utility of radiography, computed tomography (CT) and magnetic resonance imaging (MRI) for the evaluation of cervical spine instability, stenosis, and cord compression is discussed. Surgical interventions, anaesthetic considerations, and the use of neurophysiological monitoring during procedures performed under general anaesthesia are reviewed. Recommendations for regular radiological imaging and neurologic assessments are presented, and the need for a more standardized approach for evaluating and managing spinal involvement in MPS IVA is addressed.

Pullout strength of thoracic pedicle screw instrumentation: comparison of the transpedicular and extrapedicular techniques.

Study Design. In vitro biomechanical comparison of two methods of pedicle screw placement in cadaveric thoracic spine vertebrae. Objective. Compare the biomechanical integrity of extrapedicular and transpedicular screw fixation under axial and sagittal pullout loads. Summary of Background Data. Extrapedicular screw placement has been advocated as a safe and effective alternative to the transpedicular screw in thoracic vertebrae. Rigorous biomechanical comparison of these two techniques is presently lacking in the literature. Methods. Thirty-seven vertebral bodies were dissected from six cadaveric thoracic spines. Each body had two polyaxial 5.0-mm screws placed: one transpedicular and one extrapedicular. The 62 screws were randomly designated for one of two loading methods: axial or sagittal. Failure load (N), taken as maximum force on the load-deformation curve, and stiffness (N/mm), calculated between 50 N and 400 N, were measured. Results. Transpedicular screws were statistically stronger in both testing methods (P = 0.008). Load direction, whether axial or sagittal, had no bearing on pullout strength (P = 0.6). Conclusions. These data indicate that transpedicular screws are biomechanically superior to extrapedicular screws. This difference is small, however, and we think that extrapedicular screws offer an excellent alternative when anatomy dictates their use with other screws in segmental spinal constructs.

The Success of Thoracoscopic Anterior Fusion in a Consecutive Series of 112 Pediatric Spinal Deformity Cases

Study Design. A retrospective review of a single surgeon consecutive series of video-assisted thoracoscopic anterior release and fusion. Objectives. To examine radiographic fusion rates and standard radiographic parameters of spinal deformity correction, as well as to identify possible complications of thoracoscopic anterior release and fusion in patients with a minimum of 2-year follow-up treated for spinal deformity. Summary of Background Data. Anterior release and fusion of the thoracic spine is indicated in the treatment of rigid scoliosis and kyphosis, the treatment or prevention of crankshaft growth, and in patients at increased risk for pseudarthrosis. Although early postoperative outcomes of video-assisted thoracoscopic anterior release/fusion exist in the literature, few data are available with follow-up greater than 2 years. Methods. A retrospective chart and radiograph review of 112 consecutive cases of thoracoscopic anterior release/fusion with open posterior instrumentation/fusion was performed. The diagnosis, indications, perioperative data, as well as early and delayed complications, were evaluated. Deformity correction and intervertebral fusion rates were assessed at latest follow-up (≥2 years). Results. The diagnoses included 50 patients with neuromuscular deformity, 42 with idiopathic deformity, 10 congenital, and 10 miscellaneous etiologies. The average operative time was 160 ± 41 minutes to excise and bone graft an average of 7 ± 2 discs, with an average blood loss of 285 ± 303 cc. The average hospital stay was 9 ± 5 days. Fourteen percent of the patients had perioperative respiratory complications that varied from atelectasis to chylothorax. There were no long-term complications associated with the anterior surgery. Scoliosis improved from 80 ± 12° to 36 ± 17°, and kyphosis from 88 ± 15° to 60 ± 20° at latest evaluation (P ≤ 0.001). Evidence of a “solid” anterior arthrodesis (with >50% filling of the disc space) was present radiographically in 75% of the disc spaces with moderate interobserver reliability of the grading system (&kgr; = 0.49). Conclusion. Thoracoscopic anterior release and fusion of the thoracic spine is a safe and effective procedure when combined with posterior instrumentation and fusion. The primary goal of increasing the flexibility of arigid spine and achieving a solid arthrodesis occurred in the vast majority of cases.

Lower body positive-pressure exercise after knee surgery

Lower body positive pressure allows unloading of the lower extremities during exercise in a pressurized treadmill chamber. This study assessed the preliminary feasibility of lower body positive pressure exercise as a rehabilitation technique by examining its effects on gait mechanics and pain, postoperatively. Fifteen patients who had arthroscopic meniscectomy or anterior cruciate ligament reconstruction participated in this study. Patients exercised for 5 minutes at 2.0 mph under three body weight conditions (normal body weight, 60% body weight, and 20% body weight) in random order. Bilateral ground reaction force, electromyographs, and dynamic knee range of motion were collected, and pain was assessed using a visual analog scale. Ground reaction forces for surgically treated and contralateral extremities were reduced 42% and 79% from normal body weight conditions when ambulating at 60% and 20% body weight, respectively. After meniscectomy, ambulatory knee range of motion decreased only at 20% body weight (37°), compared with normal body weight conditions (49°). Peak electromyographic activity of the biceps was maintained at all body weight conditions, whereas that of the vastus medialis was reduced at 20% body weight. Pain relief was significant with lower body positive pressure ambulation after anterior cruciate ligament reconstruction. This study showed that lower body positive pressure exercise is effective at reducing ground reaction forces, while safely facilitating gait postoperatively. Level of Evidence: Therapeutic study, Level II-1 (study of untreated controls from a previous randomized controlled trial)

Definition of two types of anterior superior iliac spine avulsion fractures

Fractures of the anterior superior iliac spine (ASIS) in adolescents are usually due to avulsion of the sartorius origin from the ASIS; however, the authors here report a second type due to avulsion of the tensor fascia lata origin. Eight patients were identified with ASIS avulsion fractures. Type II sartorius avulsion fracture was due to sprinting in various sports (n = 6). The fragment was smaller and displaced anteriorly. Type II tensor fascia lata avulsion fractures were due to swinging a baseball bat. The two muscular males were both injured during the initial phase of batting. The bony fragment was much larger and displaced laterally as confirmed by three-dimensional computed tomography scans.

Treatment of hip dysplasia in patients with mucopolysaccharidosis type I after hematopoietic stem cell transplantation: results of an international consensus procedure

BackgroundMucopolysaccharidosis type I (MPS-I) is a lysosomal storage disorder characterized by progressive multi-organ disease. The standard of care for patients with the severe phenotype (Hurler syndrome, MPS I-H) is early hematopoietic stem cell transplantation (HSCT). However, skeletal disease, including hip dysplasia, is almost invariably present in MPS I-H, and appears to be particularly unresponsive to HSCT. Hip dysplasia may lead to pain and loss of ambulation, at least in a subset of patients, if left untreated. However, there is a lack of evidence to guide the development of clinical guidelines for the follow-up and treatment of hip dysplasia in patients with MPS I-H. Therefore, an international Delphi consensus procedure was initiated to construct consensus-based clinical practice guidelines in the absence of available evidence.MethodsA literature review was conducted, and publications were graded according to their level of evidence. For the development of consensus guidelines, eight metabolic pediatricians and nine orthopedic surgeons with experience in the care of MPS I patients were invited to participate. Eleven case histories were assessed in two written rounds. For each case, the experts were asked if they would perform surgery, and they were asked to provide information on the aspects deemed essential or complicating in the decision-making process. In a subsequent face-to-face meeting, the results were presented and discussed. Draft consensus statements were discussed and adjusted until consensus was reached.ResultsConsensus was reached on seven statements. The panel concluded that early corrective surgery for MPS I-H patients with hip dysplasia should be considered. However, there was no full consensus as to whether such a procedure should be offered to all patients with hip dysplasia to prevent complications or whether a more conservative approach with surgical intervention only in those patients who develop clinically relevant symptoms due to the hip dysplasia is warranted.ConclusionsThis international consensus procedure led to the construction of clinical practice guidelines for hip dysplasia in transplanted MPS I-H patients. Early corrective surgery should be considered, but further research is needed to establish its efficacy and role in the treatment of hip dysplasia as seen in MPS I.

Musculoskeletal manifestations of Sanfilippo Syndrome (mucopolysaccharidosis type III).

Background The most pronounced symptom in mucopolysaccharidosis type III (MPS III, Sanfilippo Syndrome) is the severe neurocognitive deterioration of the central nervous system. The effects of MPS III on the musculoskeletal system are less severe than those caused by other forms of MPS, however, it is our experience that many families seek orthopaedic attention for perceived musculoskeletal discomfort, particularly about the hip and spine. The purpose of this study is to report musculoskeletal findings in a case series of patients with MPS III. Methods This study represents a retrospective case series of all records available from 2 institutions on patients with MPS III. Chart and radiographic review was performed and outcomes tabulated. Our hypotheses are: (1) Musculoskeletal abnormalities are prevalent in children with MPS III and (2) Musculoskeletal deformities in children with MPS III may require surgical intervention. Results Eighteen patients were identified (10 female and 8 male) with an average age of 10.3 years. Three had significant scoliosis (21 to 99 degrees) and 2 others had L1 hypoplasia. Four patients had osteonecrosis of the femoral heads. One patient required a carpal tunnel release, and another a trigger thumb release. There were no cases of cervical instability. Conclusions In our study with these patients, we have observed several unreported musculoskeletal manifestations of MPS III. Osteonecrosis of the hips can be a source of severe discomfort for these children. Although uncommon, operative intervention for orthopaedic conditions is sometimes warranted. Operative indications in this cohort include progressive scoliosis of large magnitude, carpal tunnel syndrome, and trigger digits. Level of Evidence Level IV; case series.