Evaluation of ankle instability using the Biodex Stability System.

Ten patients with chronic unilateral functional lateral instability of the ankle were evaluated using the Biodex Stability System. This system uses a multiaxial testing platform which can be set at variable degrees of instability. Patients are then tested for their ability to "balance" the platform during single-limb stance, and a stability index is electronically generated. This stability index is believed to be an objective measurement that correlates with proprioceptive status of the ankle. Instability of the ankle was confirmed in all 10 patients, using stress radiographs. Two levels of platform stability were tested. With the platform in its most stable configuration, there was minimal difference between the previously injured and the uninjured ankle. With the platform set to permit up to 20 degrees of tilt in any plane, 6 of 10 patients had more difficulty balancing the platform with their injured ankle (higher stability index). This preliminary study suggests that the Biodex Stability System may be a useful tool in trying to objectively measure proprioceptive function.

Tendon interposition in a juxta-epiphyseal fracture of the proximal phalanx.

Juxta-epiphyseal fractures of the proximal phalanx are relatively common. A case report and literature review calls attention to the possibility of entrapment of either a flexor or extensor tendon in this type of fracture.

Osteosarcoma and its variants.

Osteosarcoma is the most common primary malignant tumor of bone. The variability of this tumor and its histologic variants in presentation, location, and biologic behavior has an influence on the prognosis and determines treatment options. Despite improvements in both survival and function due to limb salvage techniques and adjuvant chemotherapy, osteosarcoma continues to be a major challenge for the medical and surgical oncologist.

Resection arthrodesis of the knee with an intercalary allograft.

Thirty-nine patients who had a malignant or an aggressive benign bone tumor about the knee were managed with a resection arthrodesis with use of an intercalary allograft fixed with an intramedullary nail. In thirty-one patients, this was the method chosen for the initial reconstruction after resection of the tumor. In eight patients, another type of reconstruction had already failed. Both the proximal and the distal allograft-host junction healed and the functional outcome was satisfactory in thirty-two patients. Non-union developed in seven patients: at one junction in six patients and at both junctions in one. In five patients, the non-union healed after bone-grafting, repeat internal fixation, or replacement of the allograft. An above-the-knee amputation was done for two patients, both of whom had had a chronic non-union. One patient had a local recurrence, and it was treated with an above-the-knee amputation.

Effects of running on the torsional strength, morphometry, and bone mass of the rat skeleton.

Intensity and duration effects of weight-bearing exercise on the rat skeleton were investigated. Eighty-four 3-month-old female Sprague-Dawley rats were assigned to control and nine exercise groups. Exercised rats were run on a treadmill for either 30, 60, or 90 min.d-1 at low (Vo2max approximately 55%), medium (VO2max approximately 65%), or high (VO2max approximately 75%) intensity 4 d.wk-1 for 10 wk. Rat femurs, tibias, and vertebrae were harvested for torsional mechanical tests, bone density assessment, and morphometry. Our results indicate exercise has a significant effect (P < 0.05) on the femoral mechanical response (energy absorbed and twist angle), tibial morphometry (cortical bone area and thickness), and tibial and vertebral bone density measurements but had no effect (P > 0.05) on bone strength when compared with control values. Higher intensity exercise decreased tibial and femoral torque (P < 0.05). Long duration exercise increased tibial and femoral stiffness and decreased twist angle and energy absorbed (P < 0.05). These results indicate bone adapts to its loading environment by increasing bone mineral density, increasing cortical bone area, increasing stiffness, decreasing energy absorbed, and decreasing twist angle. High-intensity exercise decreased the maximum force the bone could withstand, whereas long duration exercise made the bone more brittle.

The short- and long-term effects of methotrexate on the rat skeleton.

Both clinical and laboratory studies have shown that the chemotherapy drug, Methotrexate (MTX), has adverse short-term effects on bone. There are no studies that demonstrate the long-term response of bone to MTX. The purpose of this study was to determine the short- and long-term effects of MTX on bone volume, turnover, mineralization and strength. Three-month-old Sprague-Dawley rats were randomly assigned to a control (CTL) or MTX group and were given either daily MTX or saline injections for two separate 5-day courses (5 on/9 off/5 on). Fluorochrome compounds were injected prior to killing to label actively mineralizing bone surfaces. One CTL and MTX group were killed at 30, 80 and 170 days after treatment. Both femurs and tibiae were harvested for cancellous and cortical bone histomorphometry and biomechanical testing (torsion). Standard cancellous and cortical histomorphometric parameters were measured from undecalcified, methyl-methacrylate-embedded sections from the right proximal tibia and tibial and femoral diaphyses. The contralateral femur and tibia were torsionally loaded to failure and standard mechanical parameters were measured. All bone responses were statistically analyzed using a two-way ANOVA followed by Duncan's multiple comparison procedure (significance: p = 0.05). Cancellous bone volume was significantly lower in the MTX-treated group at 80 and 170 days. Cancellous mineralizing surface and longitudinal bone growth were significantly depressed at all time points yet mineral apposition rate was only depressed at the 170-day point. Cancellous osteoclast surface was increased at all time points for the MTX-treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)

A biomechanical comparison of four fixation methods of first metatarsophalangeal joint arthrodesis.

A simulated metatarsophalangeal joint arthrodesis was performed on 18 pairs of cadaveric great toes. One toe of each pair was fixed with a 4.0-mm oblique AO cancellous screw. The contralateral toe was fixed with one of three techniques: (1) a miniplate placed dorsally; (2) a 4.5-mm Herbert cannulated screw placed from the metatarsal neck into the medullary canal of the proximal phalanx; or (3) a 3/32-inch Steinmann pin placed longitudinally. An oblique 0.045 Kirschner wire was added with each method. The specimens were tested to failure in dorsiflexion. The miniplate was significantly stronger than the AO screw in force to failure and initial stiffness. The Herbert cannulated screw was also significantly stronger in force to failure than the AO screw. There was no significant strength difference between the Steinmann pin and the AO screw.

The effect of internal fixation on the healing of large allografts.

One hundred and twenty patients had an allograft reconstruction of the femur, tibia, or humerus. Of a total of 183 allograft-host junctions, eight-three were fixed with a plate; ninety-eight, with an intramedullary rod; and two, with screws alone. There was no significant difference between the rate of union after fixation with a plate and that after intramedullary fixation (p = 1.00). However, fixation with a plate was associated with a higher rate of fracture of the allograft (p < 0.0001). Some problem related to the internal fixation of the allograft was identified at eighteen of the twenty junctions that did not heal. There was a significant association (p < 0.001) between a problem in the achievement of stable fixation and the development of a non-union at the allograft-host junction.

Reconstruction of the humerus with an intramedullary fibular graft. A clinical and biomechanical study.

Nine patients with nonunited humeral shaft fractures were treated by open reduction and internal fixation with an intramedullary fibular bone graft and a compression plate. Fixation of the screws was enhanced by passing them through the fibula as well as the two humeral cortices (quadricortical fixation). Eight of the nine fractures united at an average of 3.5 months. Tests on cadaver bones showed that quadricortical fixation was as strong as methylmethacrylate augmentation and significantly better than bicortical fixation.

The treatment of giant-cell tumors of the distal part of the radius.

We reviewed the results of the treatment of giant-cell tumors of the distal part of the radius in twenty-three patients, to identify criteria that could assist in the selection of the most effective option for treatment or reconstruction. The treatment was chosen on the basis of the preoperative roentgenographic assessment of the extent of the tumor. Seven patients, who had received previous treatment elsewhere, were referred to us because of a local recurrence. An extended curettage followed by packing of the cavity with cement was effective in preserving the normal function of the extremity and in eradicating the lesion in five patients who had a lesion that was intraosseous or that involved minimum cortical perforation. Of the eighteen remaining patients, who had extraosseous extension of the tumor, seventeen had a resection of the distal part of the radius and one had a below-the-elbow amputation. After resection of the involved segment of bone, the best functional result was seen in the patients who had been managed with a radiocarpal arthrodesis and use of an intercalary bone graft that was stabilized with a long plate. At the most recent follow-up examination (range, two to nineteen years after the curettage or resection), there had been no local recurrences.

Osteosarcoma of the pelvis. A clinical and histopathological study of twenty-five patients.

Twenty-five patients who had an osteosarcoma of the pelvis were treated at the University of Florida between 1967 and 1990. Two of these patients had underlying Paget disease, and five had received previous radiation therapy to the pelvis. Common problems in this series of patients included delays and errors in establishment of the diagnosis, underestimation of the extent of the tumor on the radiographic staging studies, histopathological findings of local extension next to and into pelvic structures, widespread invasion into major pelvic veins, and microscopic foci of tumor in otherwise normal tissue. These problems led to difficulty in gaining local control of the tumor with any type of operative procedure. Of the eighteen patients who had a resection, only four had a contamination-free wide margin, and a local recurrence developed in thirteen. Only one patient, who had no evidence of disease eleven years after treatment, was alive at the time of writing. Because of the tendency for venous invasion, the radiographic staging studies should include a thorough evaluation of the blood vessels adjacent to the tumor.

Orthopedic fixation devices.

Orthopedic fixation devices are used in the treatment of fractures, soft-tissue injuries, and reconstructive surgery. After fracture reduction, internal, external, or intramedullary fixation devices may be used to provide stability and maintain the alignment of bone fragments during the healing process. They must be strong and secure enough to allow early mobilization of the injured part, as well as the entire patient. Compression is used whenever possible to increase the contact area and the stability between fragments and to decrease the stress on the implant. Screws are used primarily to provide interfragmental compression or to attach plates, which can then provide compression, prevent displacement, and support the fragments during healing. Pins and wires can be used for fixation of small fragments or fractures in small bones and for attachment of external fixation devices and traction. A basic understanding of the devices and principles of use is needed to interpret radiographs obtained after the treatment of musculoskeletal injuries.

Treatment of ipsilateral fractures of the distal femur and femoral shaft.

Thirteen patients with segmental fractures involving the distal femur and femoral shaft were treated with internal fixation. Nine of the distal femur fractures were intraarticular. Priority was given to restoration of the articular surface and the alignment of the distal femur. No single method of fixation could be used for all patients. Nine patients were treated using plate fixation with one or more plates. Three patients were treated with a combination of an interlocked intramedullary nail and lag screw fixation. One patient was treated with Ender nails. All the fractures eventually healed, but the recovery time was long. Although no patient was asymptomatic, 10 have resumed their preinjury level of function.

The effect of local extent of the tumor on prognosis in osteosarcoma.

The effect of local extent of the tumor on disease-free survival was studied in fifty-one patients who had an osteosarcoma, all of whom were treated according to the same protocol. Disease-free survival was defined as the interval between entry into the protocol and local recurrence, metastasis, or death (whichever occurred first). All patients had a Stage-IIB intramedullary osteosarcoma--that is, a high-grade malignant tumor (Stage II) with cortical penetration (B). The tumors were subdivided on the basis of the amount of local extension: E1--the tumor touches but does not elevate or penetrate the periosteum; E2--the tumor elevates but does not penetrate the periosteum; E3--the tumor penetrates into, but not through, the periosteum; E4--there is minimum extraperiosteal extension without invasion of another structure, such as a muscle, tendon, or ligament; E5--the tumor invades one additional structure (a muscle, ligament, or tendon); and E6--the tumor invades two or more structures adjacent to the bone. When the tumor had invaded two or more adjacent structures (E6), the instantaneous risk of failure was estimated to be 5.9 times greater than when the tumor had a lesser extent (E1 through E5). The relative prognostic importance of the amount of local extension, the size of the tumor, and the sex and age of the patient was compared with forward step-wise Cox multivariate analysis. Only the amount of local extension had a significant effect on disease-free survival. The estimated cumulative probabilities of disease-free survival at five years, according to the Kaplan-Meier method, were 49.1 +/- 8.5 per cent for patients who had a Stage-IIB tumor, 79.8 +/- 9.3 per cent for those who had a Stage-IIB but not E6 tumor, and 17.6 +/- 11.3 per cent for those who had a Stage-IIB E6 tumor. These data suggest that, with respect to prognosis, there are two distinct subgroups of Stage-IIB osteosarcomas that can be objectively defined by the amount of local extension.

Response of osteogenic sarcoma to the combination of etoposide and cyclophosphamide as neoadjuvant chemotherapy.

A Phase II study of the combination of etoposide (VP-16) and cyclophosphamide (CPM) was conducted in an attempt to identify active and potentially less toxic agents for treating patients with osteogenic sarcoma (OS). VP-16 was given as a 72-hour infusion for a total dose of 600 mg/m2. CPM was given as six pulses of 300 mg/m2 every 12 hours for a total dose of 1800 mg/m2. Seventeen newly diagnosed patients, including five (29%) with metastatic disease, were evaluated before and after two courses of VP-16 and CPM for clinical, radiologic, and biochemical (serum alkaline phosphatase [SAP]) responses of the primary tumor and metastases. Fifteen (88%) patients achieved complete or partial clinical responses. Fourteen (82%) patients achieved radiologic responses. Thirteen (87%) of 15 patients with higher than normal SAP levels for their age showed partial or complete responses. Three (60%) of the five patients with metastatic disease achieved complete or partial responses. The only major toxicity was myelosuppression, which led to 21 (62%) brief admissions after 34 courses of chemotherapy for intravenous antibiotic therapy for fever and neutropenia, without associated mortality. It was concluded that the combination of VP-16 and CPM is effective chemotherapy for both primary and metastatic OS. Although myelosuppression is inevitable, it is rapidly reversible in the drug dosages used. Further studies are needed to evaluate the effect of these drugs in combination with established agents in improving the disease-free survival of patients with OS.

Open reduction and internal fixation of three-part fractures of the proximal humerus.

Eleven patients with 12 three-part fractures of the proximal humerus were treated by open reduction and internal fixation using AO/ASIF buttress plating. All of the fractures healed. There were no failures of fixation. Nine of these patients returned for a follow up of more than 2 years and had a satisfactory rating using Neer's shoulder rating system. Five patients who had an acromioplasty at the time of their initial surgery had slightly better function and range of motion than the remaining patients. Successful operative treatment requires accurate definition of the fracture pattern, careful attention to the details of internal fixation, and supervised postoperative rehabilitation.

Performance evaluation of a cement-augmented intramedullary fixation system for pathologic lesions of the femoral shaft.

To improve intramedullary fixation with polymethylmethacrylate for use in pathologic bone, a new fixation system was developed. A fluted intramedullary rod was modified to allow injection of low-viscosity polymethylmethacrylate (PMMA) through the rod with retrograde filling of the void spaces between the rod and the medullary canal. This provided uniform distribution of the cement along the length of the rod and significantly improved fixation stability. Biomechanical testing using this system on simulated pathologic lesions of the femur showed a twofold increase in torsional strength over intramedullary methods previously used, with strength approaching that of the intact femur. In 16 patients, the device made mobilization possible immediately after the operation.

Tibial plateau fractures. A review of operative treatment using AO technique.

In a retrospective review of 80 tibial plateau fractures, 28 fractures were treated nonoperatively with a variety of closed methods and 52 were treated with open reduction and internal fixation using AO technique. At an average follow up of 24 months, a satisfactory result was obtained in 87% of the operatively treated patients and in 66% of those treated nonoperatively. It appears that stable, minimally displaced fractures do equally well with closed or open treatment. Patients with depressed, displaced, or unstable fractures did better with operative treatment. When operative treatment is planned the principles and techniques of internal fixation should be carefully followed.