Chun-Hsiung Shih

Two-Stage Revision Hip Arthroplasty for Infection: Comparison Between the Interim Use of Antibiotic-Loaded Cement Beads and a Spacer Prosthesis

BACKGROUND A two-stage revision is a well-accepted method for the treatment of a deep infection of a hip with a joint implant. In the present study, the results associated with the interim use of antibiotic-loaded cement beads were compared with those associated with the interim use of an antibiotic-loaded cement prosthesis. METHODS One hundred and twenty-eight consecutive patients who were managed with a two-stage revision hip arthroplasty for the treatment of an infection were followed clinically and radiographically for an average of 4.9 years. Cement beads were implanted following resection arthroplasty in the first seventy hips, and a custom cement prosthesis was implanted in the subsequent fifty-eight hips. RESULTS There was no evidence of recurrent infection in 122 patients (95.3%); the infection-free rates in both groups were similar. The use of a spacer prosthesis was associated with a higher hip score, a shorter hospital stay, and better walking capacity in the interim period; a decreased operative time, less blood loss, and a lower transfusion requirement at the time of reimplantation; and fewer postoperative dislocations. CONCLUSIONS The present study supports the safety and efficacy of the routine use of an antibiotic-loaded cement prosthesis in the interim between the stages of a two-stage revision procedure for the treatment of an infection at the site of a hip arthroplasty.

Closed management and percutaneous fixation of unstable proximal humerus fractures.

BACKGROUND In dealing with displaced proximal humerus fractures, there is still much controversy in treatment modalities. The latest investigations emphasize the concept of minimal exposure and rigid fixation. METHODS The technique of closed reduction and percutaneous fixation with cannulated screws and k-pins was performed on 19 patients with two- and three-part proximal humerus fractures. The outcomes were evaluated with a mean follow-up of 21 months. RESULTS All except one case had a solid union of the fracture. Sixteen of 19 patients (84%) acquired good or excellent results according to Neers classification. No further collapse or avascular necrosis was found. CONCLUSION The method of closed reduction and percutaneous fixation, although technically demanding, yields satisfactory results in displaced proximal humerus fracture. Cannulated screws provided rigid fixation that was the underlying tenet for early functional retrieval.

Management of femoral diaphyseal infected nonunion with antibiotic beads local therapy, external skeletal fixation, and staged bone grafting

BACKGROUND Fifteen patients with femoral shaft fractures complicated by infected nonunions were treated with a two-stage protocol. METHODS In the first stage, radical debridement was performed along with antibiotic bead chains local therapy and external skeletal fixation. In the second stage, the debrided nonunion site was repaired with bone grafting and the external skeletal fixator was used until bony union was achieved. The time between the first and second stages of treatment was 2 to 6 weeks. The debrided bone defects ranged from 0.5 to 15 cm. Autogenous iliac cancellous bone grafting was performed in 11 patients, and microvascularized osteoseptocutaneous fibular transfer was performed in 4 patients. RESULTS Wound healing and bone union were achieved in all 15 cases. The duration of external fixation of these patients ranged from 7 to 15 months, with an average of 9 months. Minor pin-track infection was seen in seven patients. Postoperative infection after the second-stage bone grafting occurred in three patients. These three infections were arrested by limited debridement along with 2 to 4 weeks of parenteral antibiotic therapy. In one case, stress fracture occurred at 11 months after microvascularized fibular transfer; this was managed with another 5 months of external skeletal fixation. With an aggressive physical therapy program, 10 patients achieved nearly full range of knee motion and 5 patients had relevant knee flexion deficits. The follow-up averaged 58 months (range, 40-76 months); no recurrence of osteomyelitis was observed even at 76 months. CONCLUSION We have found that our two-stage treatment with antibiotic beads local therapy, definitive external skeletal fixation, and staged bone grafting is an acceptable treatment protocol for the management of femoral diaphyseal infected nonunion. It results in rapid recovery from osteomyelitis and a predictable recovery from nonunion.

Bone healing of tibial lengthening is enhanced by hyperbaric oxygen therapy: a study of bone mineral density and torsional strength on rabbits.

We investigated the effect of intermittent hyperbaric oxygen (HBO) therapy on the bone healing of tibial lengthening in rabbits. Twelve male rabbits were divided into two groups of six animals each. The first group went through 2.5 atmospheres absolute of hyperbaric oxygenation for 2 hours daily, and the second group did not go through hyperbaric oxygenation. Each animals right tibia was lengthened 5 mm using an uniplanar lengthening device. Bone mineral density (BMD) study was performed for all of the animals at 1 day before operation and at 3, 4, 5, and 6 weeks after operation. All of the animals were killed at 6 weeks postoperatively for biomechanical testing. Using the preoperative BMD as an internal control, we found that the BMD of the HBO group was increased significantly compared with the non HBO group. The mean %BMD at 3, 4, 5, and 6 weeks were 69.5%, 80.1%, 87.8%, and 96.9%, respectively, in HBO group, whereas the mean %BMD were 51.6%, 67.7%, 70.5%, and 79.2%, respectively, in non-HBO group (two tailed t test, p < 0.01, p < 0.01, p < 0.01, and p < 0.01 at 3, 4, 5, and 6 weeks, respectively). Using the contralateral nonoperated tibia as an internal control, we found that torsional strength of lengthened tibia of the HBO group was increased significantly compared with the non-HBO group. The mean percent of maximal torque was 88.6% in HBO group at 6 weeks, whereas the mean percent of maximal torque was 76.0% in non-HBO group (two-tailed t test, p < 0.01). The results of this study suggest that the bone healing of tibial lengthening is enhanced by intermittent hyperbaric oxygen therapy.

Treatment of femoral neck nonunions with a sliding compression screw: comparison with and without subtrochanteric valgus osteotomy.

BACKGROUND The aim of this prospective study was to investigate and compare the results of treatment of femoral neck nonunions using a sliding compression screw (SCS) with and without subtrochanteric valgus osteotomy (SVO). METHODS Thirty-two consecutive patients with femoral neck nonunions, which sustained no osteonecrosis of the femoral head based on bone scan study, were prospectively treated with SCS with (21 patients) or without (11 patients) SVO. The indication for SCS with SVO was a femoral neck nonunion with leg shortening of more than 1.5 cm. SCS without SVO was for leg shortening of less than 1.5 cm. RESULTS Seventeen patients with osteotomy and nine patients without osteotomy were followed for at least 2 years (range, 2-8 years). All femoral neck fractures healed, with a union period of 4.6+/-1.0 months (95% confidence interval, 4.1-5.1 months) for osteotomy cases and 4.6+/-1.1 months (95% confidence interval, 3.8-5.4 months) for nonosteotomy cases (p = 0.83). However, in the osteotomy group, two patients sustained osteonecrosis of the femoral head, and nonunion remained in 1 patient at the osteotomy site (complication rate, 18%; 3 of 17 patients). There were no complications in the nonosteotomy group (p = 0.26). The average lengthening achieved from osteotomy was 1.0 to 1.5 cm (p < 0.001). CONCLUSION Using SCS without SVO to treat femoral neck nonunions can result in a very satisfactory outcome. It is thus preferred for indicated patients. SCS without SVO, however, cannot concomitantly correct a femoral neck shortening; furthermore, shortening may deteriorate because of a telescoping effect. For patients with evident shortening, therefore, combined SVO with SCS is more suitable.

Early polyethylene wear and osteolysis in cementless total hip arthroplasty: the influence of femoral head size and polyethylene thickness.

We examined initial polyethylene thickness, early polyethylene liner wear, and osteolysis in 350 primary, cementless total hip arthroplasties (THAs). All of the prostheses were of identical design and used Omnifit components. In the 32-mm head group, the mean liner wear correlated significantly with polyethylene thickness (P<.001) and increased rapidly with initial thinner polyethylene following a logarithmic model, although this increase was not statistically significant (r = -.633). Inadequate polyethylene thickness in the 32-mm head group was implicated as the major cause of higher liner wear. A minimal polyethylene thickness of 7 mm is recommended in cementless metal-backed THAs. The use of a large head combined with poor prosthetic design appeared to be responsible for the unacceptably high incidence of femoral osteolysis.

Bone healing of tibial lengthening is delayed by cigarette smoking : Study of bone mineral density and torsional strength on rabbits

OBJECTIVE We investigated the effect of intermittent cigarette smoke inhalation on the bone healing of tibial lengthening in rabbits. METHODS Twelve male rabbits were divided into two groups of six animals each. The first group underwent intermittent cigarette smoke inhalation, and the second group did not undergo intermittent cigarette smoke inhalation. Each animals right tibia was lengthened 5 mm by using an uniplanar lengthening device. Bone mineral density (BMD) study was performed for all of the animals 1 day before operation and 3, 4, 5, and 6 weeks after operation. All of the animals were killed 6 weeks postoperatively for biomechanical testing. RESULTS By using the preoperative BMD as an internal control, we found that the BMD of the smoke-inhalation group was decreased significantly compared with the non-smoke-inhalation group. The mean %BMD at 3, 4, 5, and 6 weeks were 49.9%, 61.2%, 65.9%, and 71.0%, respectively, in the smoke-inhalation group, whereas the mean %BMD were 54.9%, 71.8%, 76.4%, and 82.0%, respectively, in the non-smoke-inhalation group (two-tailed t test, p > 0.05, p < 0.01, p < 0.01 and p < 0.01 at 3, 4, 5, and 6 weeks, respectively). By using the contralateral nonoperated tibia as internal control, we found that torsional strength of the smoke-inhalation group was decreased significantly compared with the non-smoke-inhalation group. The mean percentage of maximal torque was 63.8% in the smoke-inhalation group, whereas the mean percentage of maximal torque was 77.1% in the non-smoke-inhalation group (two tailed t test, p < 0.01). CONCLUSION This study suggests that cigarette smoking delays the mineralization during the bone healing process of distraction osteogenesis and, thus, decreases the mechanical strength of the regenerating bone.

Biomechanical analysis of location of lag screw of a dynamic hip screw in treatment of unstable intertrochanteric fracture.

OBJECTIVE The aim of this study was to assess the most adequate location of a lag screw of a dynamic hip screw in the treatment of an unstable intertrochanteric fracture. METHODS Six pairs of proximal femora obtained from fresh adult cadavers were inflicted with iatrogenic unstable intertrochanteric fractures. Fractures of both sides were stabilized with two different favored locations of a lag screw and tested by a Material Testing System machine with increased loads to evaluate the relative migration of the femoral head. RESULTS There was significant difference (p < 0.05) with less migration of the femoral head by inferior insertion of a lag screw in the frontal plane and central insertion in the coronal plane. CONCLUSIONS Based on theoretical and experimental considerations, the most adequate location of a lag screw of a dynamic hip screw should be inferior in the frontal plane and central in the coronal plane.

Development of a biodegradable antibiotic delivery system.

Antibiotic beads have been used as a drug delivery system for the treatment of various surgical infections. In this study, the copolymer 50:50 poly(DL-lactide):co-glycolide was mixed with vancomycin powder and hot compressing molded at 55 degrees C to form five types of biodegradable antibiotic beads. The beads were placed in 1 mL of phosphate buffered saline and incubated at 37 degrees C. The phosphate buffered saline was changed daily, and the removed buffer solutions were stored at -70 degrees C until the antibiotic concentration in each sample was determined by high performance liquid chromatography system assay. The concentration of vancomycin in each sample was well above the breakpoint sensitivity concentration (the antibiotic concentration at the transition point between bacterial killing and resistance to the antibiotic) for more than 32 days. The release was most marked during the first 48 hours. All copolymer 50:50 poly(DI lactide):co-glycolide biodegradable beads released high concentrations of the antibiotics in vitro for the time needed to treat bone infections (4 to 6 weeks). The diameter of the sample inhibition zone ranged from 6.5 mm to 10 mm, and the relative activity of vancomycin ranged from 12.5% to 100%. Copolymers with low heat of formation temperatures are required for making a controlled release system to prevent antibiotic decomposition, which occurs when using the hot compressing molded method. The rate and duration of release from the antibiotic beads can be adjusted by varying the diameter of the beads. This offers a convenient method to adjust the release rate to meet the specific antibiotic requirements for different patients.

Management of Large Infected Tibial Defects with Antibiotic Beads Local Therapy and Staged Fibular Osteoseptocutaneous Free Transfer

Fifteen patients with tibial fractures complicated by large infected tibial defects were treated with a two-stage protocol. In the first stage, antibiotic-impregnated polymethylmethacrylate bead chains were used to obliterate the debrided osseous defect, and a meshed porcine skin was used for temporary wound coverage. In the second stage, the bead chains were removed, and the defects were reconstructed with a microvascularized fibular osteoseptocutaneous free transfer. The time between the first and second stages of treatment was 2 to 6 weeks. The bone defects ranged from 6 to 16 cm, and the skin defect areas ranged from 10 to 82 cm2. Wound healing and bony union were achieved in all 15 cases. An additional muscle flap or skin graft was required for only three patients with a large skin defect. Minor pin tract infections were seen in two patients. Stress fractures in three cases were successfully managed with bracing, external skeletal fixation or plating, and cancellous bone grafting. All of the most recent roentgenograms showed good consolidation and hypertrophy of grafted fibular bones. No recurrence of osteomyelitis was observed during an average follow-up period of 50 months (range, 36-86 months). We therefore conclude that this treatment protocol provides rapid recovery from osteomyelitis. The fibular osteoseptocutaneous graft is a useful method for the reconstruction of a large tibial defect, and it also offers the unique advantage of simultaneously reconstructing a moderate skin defect.