United States Experience With a Femoral Neck Retaining Total Hip Arthroplasty Stem: A Retrospective Study With Control Comparison From the Literature.

BACKGROUND: Femoral neck retaining prostheses have gained popularity in Europe, but the United States has not seen the same trends occurring. Previous reports demonstrate high survivorship for these implants, but to our knowledge, there are no reports examining US data. METHODS: After institutional review board approval, 824 primary total hip arthroplasties utilizing a femoral neck-retaining prosthesis were examined for femoral component survivorship rates. European studies were systematically reviewed to determine survivorship rates. The data were used to formulate a Kaplan-Meier survivorship curve and compare US data to that of the European studies. RESULTS: European studies demonstrated survivorship rates for all causes of 97.7 and 99.0% for aseptic loosening at an average of 6 years (range, 4.5 to 10). The current study demonstrated an all-cause 94% Kaplan-Meier survivorship estimate at 5 years and when aseptic loosening only was considered, survivorship increased to 99.4% at 5 years and 98.4% at 11 years. CONCLUSION: This femoral neck-retaining prosthesis demonstrated excellent survivorship that is comparable to the rates seen in European studies as well as the rates of standard and mid-stem prostheses in the United States.

Compression of the Rectum, Bladder, and External Iliac Vein Due to Hip Arthroplasty-Related Pseudotumor.

A 58-year-old male who underwent left total hip arthroplasty in 1988 for post-traumatic arthritis after an operatively-treated acetabular fracture presented with progressive left hip pain, lower extremity swelling, urinary urgency, constipation, and tenesmus (the feeling of needing to pass stool despite having an empty colon). Imaging demonstrated massive pseudotumor causing iliac vein compression and significant displacement of the rectum and bladder requiring decompression in combination with general surgery followed by revision hip arthroplasty four months later. This case highlights a unique constellation of symptoms due to pseudotumor after total hip arthroplasty, as well as the severity to which pseudotumor can progress, requiring staged decompression with general surgery before revision.

Titanium mesh as a low-profile alternative for tension-band augmentation in patella fracture fixation: A biomechanical study.

OBJECTIVES: We performed a simple biomechanical study to compare the fixation strength of titanium mesh with traditional tension-band augmentation, which is a standard treatment for transverse patella fractures. We hypothesised that titanium mesh augmentation is not inferior in fixation strength to the standard treatment. METHODS: Twenty-four synthetic patellae were tested. Twelve were fixed with stainless steel wire and parallel cannulated screws. Twelve were fixed with parallel cannulated screws, augmented with anterior titanium mesh and four screws. A custom test fixture was developed to simulate a knee flexed to 90°. A uniaxial force was applied to the simulated extensor mechanism at this angle. A non-inferiority study design was used to evaluate ultimate force required for failure of each construct as a measure of fixation strength. Stiffness of the bone/implant construct, fracture gap immediately prior to failure, and modes of failure are also reported. RESULTS: The mean difference in force at failure was -23.0 N (95% CI: -123.6 to 77.6N) between mesh and wire constructs, well within the pre-defined non-inferiority margin of -260 N. Mean stiffness of the mesh and wire constructs were 19.42 N/mm (95% CI: 18.57-20.27 N/mm) and 19.49 N/mm (95% CI: 18.64-20.35 N/mm), respectively. Mean gap distance for the mesh constructs immediately prior to failure was 2.11 mm (95% CI: 1.35-2.88 mm) and 3.87 mm (95% CI: 2.60-5.13 mm) for wire constructs. CONCLUSIONS: Titanium mesh augmentation is not inferior to tension-band wire augmentation when comparing ultimate force required for failure in this simplified biomechanical model. Results also indicate that stiffness of the two constructs is similar but that the mesh maintains a smaller fracture gap prior to failure. The results of this study indicate that the use of titanium mesh plating augmentation as a low-profile alternative to tension-band wiring for fixation of transverse patella fractures warrants further investigation.

Pelvic crescent fractures: variations in injury mechanism and radiographic pattern.

Pelvic crescent fracture, also known as sacroiliac fracture-dislocation, is traditionally considered as a lateral compression injury and a vertically stable injury. Thirty consecutive cases were analyzed and it was found that 63% of cases were caused by lateral compression (LC), 27% by anteroposterior compression (APC), and 10% by vertical shear (VS). APC and VS injuries cause significant displacement of the anterior iliac fragment, but 21% of LC injury cases showed minimal displacement and were treated successfully with nonoperative treatment. Different injury mechanisms also produce different types of pelvic instability. More important, different injury mechanisms produce distinct radiographic fracture patterns regarding the obliquity of the fracture line and fracture surface. These differences in the fracture pattern will influence the decision of internal fixation options. Therefore, treatment of pelvic crescent fractures should be based on individual analysis of injury mechanism and radiographic fracture pattern.

Management of posttraumatic segmental bone defects.

Because of difficulty in managing posttraumatic segmental bone defects and the resultant poor outcomes, amputation historically was the preferred treatment. Massive cancellous bone autograft has been the principal alternative to amputation. Primary shortening or use of the adjacent fibula as a graft also has been used to attempt limb salvage. Of more recent methods of management, bone transport with distraction osteogenesis has been suggested as the leading option for defects of 2 to 10 cm, but problems include delayed union at the docking site and prolonged treatment time. Free vascularized bone transfer has been suggested as the leading option for defects of 5 to 12 cm, but hypertrophy of the graft is unreliable and late fracture, common. Bone graft substitutes continue to be developed, but they have not yet reached clinical efficacy for posttraumatic segmental bone defects. Although each of the new techniques has shown some limited success, complications remain common.