Quantitative volumetry of cement leakage in viscosity-controlled vertebroplasty.

STUDY DESIGN: This study was designed as a cohort study comparing a prospective sample to a historic control group. OBJECTIVE: The aim of the actual trial was to compare the rate of cement leakage by quantitative volumetry comparing viscosity-controlled and non-viscosity-controlled vertebroplasty. SUMMARY OF BACKGROUND DATA: Percutaneous vertebroplasty (PVP) is a widespread safe and effective technique in the treatment of osteoporotic compression fractures and vertebral metastatic lesions. However, cement leakage has been identified as a problem of this technique. The leakage rates are reported to range from 7% to 90%. The main influence factor for leakage has been demonstrated to be cement viscosity. Assessment of appropriate injection viscosity is highly subjective and observer dependent. Viscosity-controlled vertebroplasty (Vertecem system) has been developed to objectively measure cement viscosity before injection. It introduces a viscosimeter to measure the actual cement viscosity before injection into the vertebra, and therefore may prevent leakages resulting from low-viscosity cement injections. Despite more than 800 Pubmed citations on PVP, there is only 1 report on distinct measurement of cement leakage by semiquantitative volumetry. METHODS: A total of 111 vertebrae in 68 patients, in which PVP was performed for osteoporotic fractures, were included. Thirty-seven patients (76 operated vertebrae) were assessed prospectively using the viscosity-controlled vertebroplasty. The results were compared with a retrospective group of 31 patients (35 operated vertebrae) undergoing PVP without using a viscosimeter. RESULTS: : There were no significant differences between the 2 groups in the applied volume of cement per fractured vertebra (P=0.73). The frequency of cement leakage in viscosimete-assisted vertebroplasty was 42.1% and 58.3% in the historic group. Cement leakage into the basivertebral vein (type B), was detected in 6.6% with and in 11.1% without viscosimetry. CONCLUSIONS: The use of viscosity-controlled vertebroplasty led to a decrease in the leakage rate from 58.3% to 42.1%. Leakage into the basivertebral vein with the risk of compression of nerval structures was reduced to almost 50% when viscosimetry was performed. It revealed to be a helpful tool for more unexperienced surgeons to assess the appropriate viscosity for vertebroplasty.

CT angiography for anterior lumbar spine access: high radiation exposure and low clinical relevance.

BACKGROUND: Some spine surgeons perform CT angiography for detailed planning of anterior access to the lumbar spine. However, the value of this imaging method and its influence on surgeons' decisions are unclear. QUESTIONS/PURPOSES: We determined (1) the dose of radiation used in preoperative CT angiography and (2) whether CT angiography affects planning of anterior lumbar spine surgeries. PATIENTS AND METHODS: We assessed preoperative CT angiograms of 28 patients undergoing anterior spine surgery. The level of aortic bifurcation, iliac vein confluence, course of the ascending lumbar vein, central sacral vessels, and any vascular variation were mapped. We determined the effective dose of radiation and recorded whether the preoperative CT angiography influenced surgical planning. RESULTS: We observed variations in the location of the aortic bifurcation and the iliac vein confluence. In 32% of patients, there were accessory renal arteries originating from the aorta; 7% had a rudimentary persistent left-sided caval vein. The findings did not change the plan for surgery in any patient. We detected high organ radiation dosages (mSv) for the stomach (63 mSv), liver (58 mSv), urinary bladder (47 mSv), and colon (46 mSv); other high exposure dosages involved the lungs, bone marrow, ovaries, and uterus. CONCLUSIONS: About one in 1919 men and one in 2971 women undergoing CT angiography therefore are expected to have colon cancer develop, and one in 2781 men and one in 2856 women are expected to have cancer of the urinary bladder develop. CT angiography is of low value for preoperative planning for anterior access to the lumbar spine and should be avoided to prevent radiation-induced damage. LEVEL OF EVIDENCE: Level II, diagnostic study.

Footprint mismatch in lumbar total disc arthroplasty.

Lumbar disc arthroplasty has become a popular modality for the treatment of degenerative disc disease. The dimensions of the implants are based on early published geometrical measurements of vertebrae; the majority of these were cadaver studies. The fit of the prosthesis in the intervertebral space is of utmost importance. An undersized implant may lead to subsidence, loosening and biomechanical failure due to an incorrect center of rotation. The aim of the present study was to measure the dimensions of lumbar vertebrae based on CT scans and assess the accuracy of match in currently available lumbar disc prostheses. A total of 240 endplates of 120 vertebrae were included in the study. The sagittal and mediolateral diameter of the upper and lower endplates were measured using a digital measuring system. For the levels L4/L5 and L5/S1, an inappropriate size match was noted in 98.8% (Prodisc L) and 97.6% (Charite) with regard to the anteroposterior diameter. Mismatch in the anterior mediolateral diameter was noted in 79.3% (Prodisc L) and 51.2% (Charite) while mismatch in the posterior mediolateral diameter was observed in 91.5% (Prodisc L) and 78% (Charite) of the endplates. Surgeons and manufacturers should be aware of the size mismatch of currently available lumbar disc prostheses, which may endanger the safety and efficacy of the procedure. Larger footprints of currently available total disc arthroplasties are required.

Inferior stability of a biodegradable cement plug. 122 total hip replacements randomized to degradable or non-degradable cement restrictor.

INTRODUCTION: Modern cementing technique demands high intramedullar cement pressure to create an optimum fixed cement support of the femoral stem. Pressure resistant, stable closure of the canal therefore is absolutely necessary. Biodegradable cement restrictors, if corresponding to above mentioned attributes, could be of immense advantage in case of potential revision surgery. MATERIAL AND METHODS: A prospective, randomized trial was performed on a consecutive series of 130 patients who underwent primary cemented total hip arthroplasty due to hip arthrosis to compare a degradable cement restrictor and a non-degradable cement restrictor in their ability to resist distal migration during stem insertion. RESULTS: The median cement plug length measured 27 mm (range -12 to 126 mm, 95% confidence interval (CI) 20-33 mm) in the biodegradable restrictor group and 15 mm (range 0-61 mm, 95% CI 12-18 mm) in the non-degradable restrictor group (P=0.003). A significant effect of the relationship between the difference of restrictor size and the diameter of the femoral canal on length of cement distal of the tip of the stem in between the two groups was evident (P=0.031). CONCLUSION: The results indicate insufficient intramedullary plug fixation of the degradable restrictor probably due to the elastic material properties which also may lead to inferior precision in restrictor size choice.

Reproducible assessment of radiolucent lines in total knee arthroplasty.

The Knee Society Total Knee Arthroplasty Radiographic Evaluation and Scoring System was introduced to encourage uniform reporting of radiographic outcome. However, the method for evaluation of radiolucent lines has been shown to be unreliable. Because it has been shown that reducing the complexity of classification systems increases reliability and reproducibility, we questioned whether a simplification of the Radiographic Evaluation and Scoring System would improve reliability and reproducibility. A new system for assessment of radiolucent lines was introduced, and the interobserver reliability and intraobserver reproducibility were studied in 100 patients with 120 total knee replacements. For the new system the mean kappa intraobserver reproducibility coefficient was 0.71 (range, 0.62-0.85) for the femoral component, 0.86 (range, 0.80-0.96) for the tibial component, and 0.58 (range, 0.46-0.75) for the patella prosthesis. The mean interobserver reliability coefficient among three observers was 0.61 (range, 0.45-0.72) for the femoral component, 0.82 (range, 0.73-0.88) for the tibial component, and 0.58 (range, 0.43-0.72) for the patella prosthesis. The new system for assessment of radiolucent lines increased reliability and reproducibility and should supplement the Knee Society's Radiographic Evaluation and Scoring System.

Categorization diminishes the reliability of hip scores.

Scoring systems frequently are used to assess the outcome of total hip arthroplasty. The result may be presented as a numeric value, or in descriptive terms such as excellent, good, fair, and poor (category system). The current study was done to investigate the influence of descriptive and numeric outcomes for interobserver reliability and interscore correlation of five different hip scores. Sixty-four patients (83 hips) were included in the study. The average age of the patients at followup was 70 years (range, 48-88 years). The average followup was 6.2 years (range, 2-17 years). For the numeric outcome a higher interobserver reliability (correlation coefficient, 0.71-0.81) and interscore correlation (correlation coefficient, 0.81-0.92) were found compared with the category system (interobserver reliability[correlation coefficient, 0.57-0.72]; interscore correlation [correlation coefficient, 0.46-0.62]). Findings from the study suggest that categorization of the results of total hip arthroplasty reduces interobserver reliability and interscore correlation.

Total knee arthroplasty infection: significance of delayed aspiration.

The records of 35 patients with total knee arthroplasty infection were reviewed to investigate the significance of delayed aspiration and the success of treatment. In 13 patients, aspiration was performed within 3 months after the onset of symptoms of infection. The median duration of treatment was 243 days, and infection was arrested in all patients. In 22 patients, aspiration was performed >3 months after the onset of symptoms. The duration of treatment was significantly longer in these patients (P<.001). Persistent infection was recorded in 8 patients, and amputation of the involved leg was done in 3 patients. Aspiration within 3 months after the onset of symptoms of infection significantly reduced the duration of treatment and increased the chances of successfully arresting infection.

Scoring systems in total knee arthroplasty.

For assessment of total knee arthroplasty outcome, various scoring systems have been introduced. The current study assessed the interobserver correlation of four commonly used total knee arthroplasty outcome scores. One hundred eighteen total knee arthroplasties were investigated by two independent observers, using the Hungerford score, the Hospital for Special Surgery score, the Knee Society score, and the Bristol score. Each score consisted of three subscores: pain, knee, and function. For the highest interobserver correlation was computed for the Bristol score (interobserver correlation coefficient, 0.88). For knee range of motion, flexion contracture, and extension lag there was high interobserver correlation (interobserver correlation coefficient > 0.8 each). For walking distance and walking aids, there also was a high interobserver correlation (interobserver correlation coefficient > 0.7 each). For clinical assessment of total knee arthroplasty, pain should be measured on a four-step system, the knee should be assessed by measurement of range of motion, extension lag, and flexion contracture, and function should be measured on a separate score assessing walking distance and walking aids.

Significance of talar distortion for ankle mobility in idiopathic clubfoot.

The abnormal bony feature found most consistently in clubfeet is talar distortion. The significance of the talar distortion for mobility of the tibiotalar joint was investigated. Twenty-seven congenital clubfeet in 19 patients were examined at a minimal followup of 20 years. In all patients Turco's posteromedial release was done because of idiopathic clubfoot. Radiographic assessment of the feet included measurement of the talocalcaneal angle and index, and the tibiocalcaneal angle. The degree of talar flattening was estimated by the ratio of the curvature of the talar dome to the length of the talar bone (radius to length ratio). Three-dimensional gait analysis was done to assess the dynamic range of ankle motion. The static range of motion was measured with a goniometer. The degree of talar flattening correlated significantly with the dynamic range of ankle motion but not with the static mobility. For assessment of idiopathic clubfoot, evaluation of talar flattening should be done because of its significance for dynamic ankle mobility.

Intrapelvic complications after total hip arthroplasty failure.

BACKGROUND: Severe total hip arthroplasty failure with central migration of prosthetic components is uncommon. If perforation of the medial acetabular wall occurs, injuries of intrapelvic structures may result. DATA SOURCES: A meta-analysis of the English literature was performed. A human pelvic cadaver was used to demonstrate the proximity of intrapelvic structures to a centrally dislocated cup. RESULTS: Fifty cases of intrapelvic injury were identified. Structures involved most frequently were the external iliac artery and the bladder. The most common types of complication included fistula formation, development of a false aneurysm, and hemorrhage. The human cadaver pelvis demonstrated the proximity of intrapelvic vessels, the bladder, the ureter, the vagina, the deferent duct, the sigmoid colon, the rectum, and the sciatic nerve to an intrapelvically intruded prosthesis. CONCLUSIONS: Failed total hip replacements should be considered to cause damage to pelvic viscera.