Extensor mechanism repair failure with use of bidirectional barbed suture in total knee arthroplasty.

Total knee arthroplasty (TKA) continues to advance as innovative devices become available. #2 PDO Quill SRS (Angiotech, Reading, Pa) bidirectional barbed suture was used for 161 primary TKAs at our facility. We report on 3 separate cases of extensor mechanism repair failure after primary TKA in which a barbed suture was used for extensor mechanism closure. Before the implementation of this device, there were no reported failures in 385 primary TKAs. We recommend that surgeons who use this device for extensor mechanism repair of a medial parapatellar arthrotomy in TKA exercise caution when operating on patients with morbid obesity, diabetes, and rheumatoid arthritis. We have discontinued use of the bidirectional barbed suture until more definitive large orthopedic studies establish its efficacy and safety.

Periacetabular reconstruction with a new endoprosthesis.

UNLABELLED: Reconstruction of the Type II pelvic resection is challenging. Currently available reconstructive options have inherent problems including graft and implant failure, pain, poor function, and high major complication rates. The periacetabular reconstruction (PAR) endoprosthesis was designed to be secured with internal fixation and bone cement to the remaining ilium and support a reconstructed acetabulum. This construct potentially avoids the complications of graft or hardware failure, while maintaining early mobilization, comfort, limb lengths, and function. We retrospectively reviewed 25 patients who underwent Type II pelvic resection and reconstruction with the PAR endoprosthesis, analyzing function, complications, and survivorship. The minimum followup was 13 months (mean, 29.4 months; range, 13 to 108 months). We compared the PAR data with the literature for the Mark II saddle endoprosthesis. The PAR's average MSTS score was 20.8 (67%), major complications occurred in 14 (56%), and implant survivorship was 84% at 2 years and 60% at 5 years. The rate of failure at the ilium-saddle interface was lower and implant survivorship higher than those in the published literature for the Mark II saddle. We recommend use of the PAR endoprosthesis for reconstruction of large defects following Type II pelvic resection. The modified saddle design provides greater inherent stability, allowing for faster rehabilitation and improved longevity without increased complications and is an improvement over the currently available saddle prostheses. LEVEL OF EVIDENCE: Level III, retrospective case series. See Guidelines for Authors for a complete description of levels of evidence.

Comparison of in situ and in vitro CT scan-based finite element model predictions of proximal femoral fracture load.

Hip fracture is a serious and common injury that can lead to permanent disability, pneumonia, pulmonary embolism, and death. Research to help prevent these fractures is essential. Computed tomographic (CT) scan-based finite element (FE) modeling is a tool that can predict proximal femoral fracture loads in vitro. Because this tool might be used in vivo, this study examined whether FE models generated from CT scans in situ and in vitro yield comparable predictions of proximal femoral fracture load. CT scans of the left proximal femur of two human cadavers were obtained in situ and in vitro, and three-dimensional FE models employing nonlinear mechanical properties were generated from each CT scan. The models were evaluated under single-limb stance-type loading by applying displacements incrementally to the femoral head. The FE-predicted fracture load (F(FE)) was the maximum femoral head reaction force. F(FE) for the in situ-derived models for the two subjects were 5.2 and 13.3% greater than for the in vitro-derived models. These results demonstrate that using CT scan data obtained in situ instead of in vitro to generate FE models can lead to substantially different predicted fracture loads. This effect must be considered when using this technology in vivo.

Scoliosis and Chiari malformation Type I in children.

OBJECT: The identification of Chiari malformations Type I (CM-Is) has increased in recent years, commonly during MR imaging for evaluation of a possible cause of scoliosis. The treatment of this abnormality remains controversial, and the expected success of treatment is unclear. The goal of the present study is to evaluate the effects of a craniotomy for CM-I decompression on scoliosis in children and adolescents. METHODS: The authors conducted a 10-year retrospective review of pediatric patients who were found to have a CM-I during evaluation for scoliosis. Seventy-nine patients were identified, ranging in age from 6 months to 18 years (median 12 years). There were 42 girls (54%) and 37 boys (46%). All were noted on MR imaging to have hydrosyringomyelia of the spinal cord. Forty-nine patients had curvatures less than 20° prior to treatment. The other 30 patients had curves ranging from 25° to 80° and underwent orthopedic follow-up and treatment. None of these patients were referred for specific neurological complaints, but 12 (16%) had neurological signs on physical examination. All were treated with a craniocervical decompression in a standard fashion. Follow-up ranged from 6 to 93 months with a median of 35 months. Magnetic resonance images obtained at 6 months postoperatively and serial standing anteroposterior spine radiographs were used to evaluate outcomes. RESULTS: On the MR images obtained 6 months postoperatively, 70 patients (89%) had a significant reduction in the syrinx with an associated ascent of the cerebellar tonsils. Persistent large syringes were treated with reoperation in 6 patients, and shunts were inserted for hydrocephalus in 2 patients. None of the 49 patients with curves less than 20° had progression of their curvature postoperatively. Of the 30 patients with curves greater than 25°, 9 had no change in the scoliosis or had a reduction in curve magnitude after Chiari decompression. This group required no further therapy and was effectively treated by Chiari decompression alone. Twenty-one patients required further scoliosis treatment after Chiari decompression; 12 required orthotic treatment, 11 received spinal instrumentation and fusion surgery, and 2 received orthoses followed by fusion and instrumentation. The severity of the curvature beyond 20° did not predict the need for spinal surgery. CONCLUSIONS: This large series reports on the efficacy of treatment for scoliosis associated with a CM-I and syrinx in children. A CM-I decompression alone was adequate treatment for mild scoliosis of less than 20°. Patients with scoliosis greater than 20° required bracing and/or spinal fusion surgery 70% of the time in addition to the CM-I decompression.

Nontraumatic, spontaneous dislocation of polyethylene tibial insert 1 year after TKA.

The authors report a case of nontraumatic, spontaneous dislocation of a polyethylene insert detected 1 year after total knee arthroplasty. The patient demonstrated initial improvement and returned to work 4 months postoperatively. At 6 months postoperatively, the patient developed pain and a clunking sensation with motion; however, he denied any traumatic precipitating events. An arthroscopic procedure revealed arthrofibrotic formations but no signs of locking mechanism failure. At 12 months postoperatively, the patient developed sudden instability, and radiographs demonstrated an anteriorly dislodged insert. Revision surgery was performed, and the insert was removed. The insert showed some signs of fatigue due to the locking mechanism. We postulated that repetitive flexion produced an anterior superior force leading to failure of the locking mechanism.

The extended-short nail system, a novel concept in the management of proximal femur fractures.

In light of recent health care reform and the aging US Medicare population, it is becoming increasingly important for orthopedic surgeons to use effective and efficient strategies for hip fracture surgery. The Extended-Short Nail System (ES nail) is a US Food and Drug Administration-approved titanium nail which is locked at the same location as the locking hole of a short intramedullary (IM) nail. The ES nail takes advantage of an "extended-short" hybrid design combining the mechanical characteristics of a long IM nail with the surgical ease of use offered with a short IM nail.

Cryoablation and resection influences patient survival for soft tissue sarcomas: impact on survivorship and local recurrence.

Cryosurgical ablation has been used successfully for treating various carcinomas and bone tumors; however, few studies report the use of cryosurgery followed by tumor resection for the treatment of soft tissue sarcomas. We evaluated local recurrence, progression of disease, histologic necrosis from the cryoablation, complications, patient survival, and functional outcomes using this approach. We retrospectively reviewed 38 patients with no prior treatment for their neoplasm who underwent cryosurgery followed by wide excision of soft tissue sarcomas. Three patients developed local recurrence. Sixteen patients had evidence of more than 95% tumor necrosis, and 11 of these had 100% histologic necrosis. We observed a difference in overall survival and disease-free survival based on the adequacy of freezing process. Patients with more than 95% necrosis had a survival rate of 94% at 2 years and 86% at 5 years, while those with less than 95% necrosis survived 53% at 2 years and 34% at 5 years. Complications included transient neuropraxia (13%), superficial wound infections (8%), and seroma (21%). Cryosurgical ablation appears a safe and effective method of devitalizing tumor cells of soft tissue sarcomas.