Revision of the stiff total knee arthroplasty

This study evaluated the improvement in range of motion after revision total knee arthroplasty (TKA) in a consecutive series of patients with TKAs presenting with pain and limited range of motion. Eleven stiff (range of motion <70 degrees ) and painful TKAs were revised with a posterior stabilized condylar prosthesis and reviewed after an average of 37.6 months (range, 24-53 months). The average range of motion increased from 39.7 degrees preoperatively to 83.2 degrees postoperatively. The mean flexion contracture decreased from 13.2 degrees to 0.9 degrees. Pain scores improved from 4.5 to 44.1, and all 11 patients were satisfied. This study shows that knee range of motion can improve significantly after revision TKA.     

Risk of periprosthetic femur fracture after anterior cortical bone windowing: a mechanical analysis of short versus long cemented stems in pigs

Background and purpose

Removal of distal cement at femoral implant revision is technically challenging and is associated with complications such as cortical perforations. A technique that can reduce the risks and operating time is to make a small cortical window in the distal femur for enhanced access. We wanted to determine whether the use of long, bridging, cemented femoral stems is necessary to reduce the risk of postoperative periprosthetic fractures after using an anterior cortical bone window.

Methods

66 fresh pig femurs underwent mechanical testing. Steel rods were implanted at 3 locations: (1) at the distal window edge, (2) 15 mm proximally to the cortical window edge, and (3) 15 mm distally. 54 femurs were tested using a 3-point bending setup and 12 femurs were tested using a torsional load setup.

Results

Load to fracture ratio and bending stiffness ratio were similar in the 3 groups, for either the 3-point bending test or the torsional load test.

Interpretation

Our findings suggest that bypass of cortical windows with a revision femoral component may not reduce the risk of periprosthetic fracture.The removal of well-fixed cement is difficult and time consuming. Various surgical techniques and instruments have been developed to facilitate cement removal: extended trochanteric osteotomy (Paprosky et al. 2001), cortical windows (Nelson and Weber 1981), cement removal osteotomes/gauges/reamers (Gray 1992), and ultrasound probes (Goldberg et al. 2007). Iatrogenic femoral host bone loss, inadvertent perforation, and femoral fracture are the main risks associated with the removal of cement (Klein and Rubash 1993).The use of cortical windows, as initially described by Nelson and Weber (1981), reduces the risk of perforation at the revision surgery, while allowing for full weight bearing. The window is typically made near the tip of the implant to facilitate distal cement removal (Moreland et al. 1986, Zweymuller et al. 2005). After removing the cement, the femur is prepared to receive the revision implant. The cortical lid, which has been removed in creating the window, is replaced and secured using a cerclage wire. The femoral prosthesis can then be inserted using standard techniques. Although the risk of perforation is less with the use of a cortical window, the risk of periprosthetic fracture remains. The risk of fracture is related to the size of the window (Panjabi et al. 1985, Larson et al. 1991). Concerns about periprosthetic fractures have led to the recommendation that the cortical window should be bypassed by 2 cortical diameters, by the femoral prosthesis (Dennis et al. 1987, Larson et al. 1991, Klein and Rubash 1993). The rule of two cortical diameters is based on a finite element model by Dennis et al. (1987). There is very little biomechanical data to support this practice. Larson and associates (Larson et al. 1991) published a mechanical study on bypassing cortical defects on canine cadavers. The size of the cortical defect used in their experiment was 50% of the diaphyseal diameter, substantially larger than the window size typically used in clinical practice. The main concern with bypassing the cortical window by 2 cortical diameters is the violation of virgin bone that would otherwise be available for possible future re-revision surgery. Zweymuller et al. (2005) reported on the use of anterior cortical windows during revision hip arthroplasty in 41 cases, where the window was not bypassed by two cortical diameters in 40 of the patients. No periprosthetic fractures were reported at an average follow-up of 7 years. These results, in addition to the present senior author''s clinical experience, raised the question of the need to bypass cortical windows to prevent periprosthetic fractures. We designed a mechanical pig cadaveric study to determine and compare the risk of periprosthetic fracture for bypassed and non-bypassed anterior cortical windows.     

Prostate-specific antigen 1.5-4.0 ng/mL: a diagnostic challenge and danger zone

Study Type – Prognosis (inception cohort) Level of Evidence 1b What’s known on the subject? and What does the study add? Large population screening trials like the ERSPC, PCPT and PLCO have noted that men with seemingly low PSA (even as low as 0.5 ng/dL) still can have prostate cancer. Despite these findings, PSA is still predominantly used as a current indicator for possible presence of prostate cancer rather than also serving as a prognostic marker. This study examines a larger number of men in a diverse US population to determine the prognostic value of a man’s baseline or first PSA.

OBJECTIVES

? To assess the value of a PSA threshold of 1.5 ng/mL as a predictor of increased prostate cancer risk over a four‐year period based on a man’s first PSA test, including racial differences. ? To review the risk of progression of benign prostatic hyperplasia (BPH) based on a similar PSA threshold.

PATIENTS AND METHODS

? A retrospective review involving 21 502 men from a large Midwestern health system was performed. ? Men at least 40 years old with baseline PSA values between 0 and 4.0 ng/mL and at least four years of follow‐up after initial PSA test were included. ? Optimal PSA threshold and predictive value of PSA for development of prostate cancer were calculated.

RESULTS

? Prostate cancer rates were 15‐fold higher in patients with PSA ≥1.5 ng/mL vs patients with PSA <1.5 ng/mL (7.85% vs 0.51%). ? African American patients with baseline PSA <1.5 ng/mL faced prostate cancer rates similar to the whole study population (0.54% vs 0.51%, respectively), while African American patients with PSA 1.5–4.0 ng/mL faced a 19‐fold increase in prostate cancer.

CONCLUSION

? Both Caucasian and African American men with baseline PSA values between 1.5 and 4.0 ng/mL are at increased risk for future prostate cancer compared with those who have an initial PSA value below the 1.5 ng/mL threshold. ? Based on a growing body of literature and this analysis, it is recommended that a first PSA test threshold of 1.5 ng/mL and above, or somewhere between 1.5 and 4.0 ng/mL, represent the Early‐Warning PSA Zone (EWP Zone). ? This should serve to inform patients and clinicians alike to future clinical activities with respect to prostate cancer and BPH.     

Biomechanical comparison of occipitoatlantal screw fixation techniques

OBJECT: The stability provided by 3 occipitoatlantal fixation techniques (occiput [Oc]-C1 transarticular screws, occipital keel screws rigidly interconnected with C-1 lateral mass screws, and suboccipital/sublaminar wired contoured rod) were compared. METHODS: Seven human cadaveric specimens received transarticular screws and 7 received occipital keel-C1 lateral mass screws. All specimens later underwent contoured rod fixation. All conditions were studied with and without placement of a structural graft wired between the skull base and C-1 lamina. Specimens were loaded quasistatically using pure moments to induce flexion, extension, lateral bending, and axial rotation while recording segmental motion optoelectronically. Flexibility was measured immediately postoperatively and after 10,000 cycles of fatigue. RESULTS: Application of Oc-C1 transarticular screws, with a wired graft, reduced the mean range of motion (ROM) to 3% of normal. Occipital keel-C1 lateral mass screws (also with graft) offered less stability than transarticular screws during extension and lateral bending (p < 0.02), reducing ROM to 17% of normal. The wired contoured rod reduced motion to 31% of normal, providing significantly less stability than either screw fixation technique. Fatigue increased motion in constructs fitted with transarticular screws, keel screws/lateral mass screw constructs, and contoured wired rods, by means of 19, 5, and 26%, respectively. In all constructs, adding a structural graft significantly improved stability, but the extent depended on the loading direction. CONCLUSIONS: Assuming the presence of mild C1-2 instability, Oc-C1 transarticular screws and occipital keel-C1 lateral mass screws are approximately equivalent in performance for occipitoatlantal stabilization in promoting fusion. A posteriorly wired contoured rod is less likely to provide a good fusion environment because of less stabilizing potential and a greater likelihood of loosening with fatigue.     

高位腰椎间盘突出症

目的：通过147例高位腰椎间盘突出症的回顾性研究,旨在提高对本症的认识,减少漏诊,误诊,方法：回顾性分析报告147例高位腰椎间盘突出,结果：治疗腰1,210例,腰2。3 32例,腰3,4 105例,其中双间隙突出34例,跳跃性突出27例,伴椎管狭窄31例。瘫痪3例,非手术治疗34例,手术113例,优47例,良8例,差92例,重点讨论了高位腰椎及椎间盘和神经根的解剖特点和临床三大特征及诊断治疗,提出对不同程度的病人用不同治疗方式以及手术中需要注意的六个问题。     

Biomechanical comparison of anterior cervical plating and combined anterior/lateral mass plating.

BACKGROUND CONTEXT: Previous studies showed anterior plates of older design to be inadequate for stabilizing the cervical spine in all loading directions. No studies have investigated enhancement in stability obtained by combining anterior and posterior plates. PURPOSE: To determine which modes of loading are stabilized by anterior plating after a cervical burst fracture and to determine whether adding posterior plating further significantly stabilizes the construct. STUDY DESIGN/SETTING: A repeated-measures in vitro biomechanical flexibility experiment was performed to investigate how surgical destabilization and subsequent addition of hardware components alter spinal stability. PATIENT SAMPLE: Six human cadaveric specimens were studied. OUTCOME MEASURES: Angular range of motion (ROM) and neutral zone (NZ) were quantified during flexion, extension, lateral bending, and axial rotation. METHODS: Nonconstraining, nondestructive torques were applied while recording three-dimensional motion optoelectronically. Specimens were tested intact, destabilized by simulated burst fracture with posterior distraction, plated anteriorly with a unicortical locking system, and plated with a combined anterior/posterior construct. RESULTS: The anterior plate significantly (p<.05) reduced the ROM relative to normal in all modes of loading and significantly reduced the NZ in flexion and extension. Addition of the posterior plates further significantly reduced the ROM in all modes of loading and reduced the NZ in lateral bending. CONCLUSIONS: Anterior plating systems are capable of substantially stabilizing the cervical spine in all modes of loading after a burst fracture. The combined approach adds significant stability over anterior plating alone in treating this injury but may be unnecessary clinically. Further study is needed to assess the added clinical benefits of the combined approach and associated risks.     

Endoscopic pelvic osteotomy for the treatment of hip dysplasia.

Adolescent and adult hip dysplasia can be surgically treated by rotating the acetabulum into a better weight-supporting position; however, open pelvic osteotomies are among the most invasive of all pediatric orthopaedic procedures. Endoscopic pelvic osteotomy offers the theoretical advantages of magnified visualization of the bone cuts, minimized surgical dissection, and rapid postoperative recovery. The technique of endoscopically assisted triple innominate osteotomy requires the combination of endoscopic skills and facility with more standard surgical approaches.     

Combination cisplatin, 5-fluorouracil and radiation therapy for locally advanced unresectable or medically unfit bladder cancer cases: a Southwest Oncology Group Study

PURPOSE: Patients with locally advanced bladder cancer or who are not medically fit for surgery are a therapeutic dilemma. Radiotherapy with or without single agent cisplatin has been the major therapeutic modality. A phase II Southwest Oncology Group trial investigated the efficacy and feasibility of 5-fluorouracil, cisplatin and radiation in this patient subset. MATERIALS AND METHODS: Eligible patients had muscle invasive bladder cancer (clinical stages T2-T4) with nodal involvement at or below the level of bifurcation of the iliac vessels, were medically or surgically inoperable, or refused cystectomy. Patients underwent pretreatment cystoscopy and detailed tumor mapping, and were treated with 75 mg. /m.2 cisplatin on day 1 and 1 gm./m.2 daily, 5-fluorouracil on days 1 to 4 and definitive radiotherapy. Chemotherapy was repeated every 28 days, twice during and twice after radiation. RESULTS: From October 1993 to April 1998, 60 patients were enrolled in study. Of the 56 eligible patients 34% had unresectable tumors, 21% were not medically fit for surgery and 45% refused cystectomy. Overall, 68% of the patients had clinical T3 tumors or greater and 22% had nodal metastasis. Treatment was completed as planned in 32 of 56 (57%) patients. The most frequent grade 3 or 4 toxicities were neutropenia, stomatitis or mucositis, diarrhea, neuropathy and nausea. There were 53 patients who were evaluable for response, although response was not determined for 18. The overall response rate was 51% (95% confidence interval [CI] 37 to 65) based on intent to treat with a complete response rate of 49% (95% CI 35 to 63). Estimated median survival of the 56 patients was 27 months (95% CI 21 to 40 months) with an overall 5-year survival of 32%. The 5-year survival of the 25 patients who refused surgery was 45%. CONCLUSIONS: Concurrent 5-fluorouracil, cisplatin and radiation therapy is feasible. Despite a promising complete response rate, the overall 5-year survival suggests the need for more effective systemic therapy. The 5-year survival of patients who refused cystectomy suggests that this combined modality may provide another alternative to cystectomy for these patients.     

Accelerating the washout of inhalational anesthetics from the Dräger Primus anesthetic workstation: effect of exchangeable internal components

BACKGROUND: To establish guidelines for the preparation of the Primus anesthetic workstation (Dr?ger, Lübeck, Germany) for malignant hyperthermia-susceptible patients, the authors evaluated the effect of replacing the workstation's exchangeable internal components on the washout of isoflurane. METHODS: Primus workstations were exposed to isoflurane, and contaminated internal components were replaced as follows: group 1, no replacement; group 2, new ventilator diaphragm; group 3, autoclaved ventilator diaphragm; group 4, autoclaved integrated breathing system; group 5, flushed integrated breathing system; group 6, autoclaved ventilator diaphragm and integrated breathing system. The fresh gas flow was set at 10 l/min, and subsequently reduced to 3 l/min when a concentration of 5 ppm was achieved. Isoflurane concentration was measured in the inspiratory limb of the circle circuit every minute. RESULTS: Washout times for isoflurane decreased in the following order: group 1 (67 +/- 6.5 min) > groups 2 and 3 (50 +/- 4.1 and 50 +/- 5.7 min, respectively) > group 5 (43 +/- 9.5 min) > group 4 (12 +/- 1.5 min) > group 6 (3.2 +/- 0.4 min). Isoflurane concentration increased approximately threefold when the fresh gas flow was reduced to 3 l/min. CONCLUSION: Washout of isoflurane increased 20-fold with the use of an autoclaved ventilator diaphragm and integrated breathing system. To prepare the Primus for malignant hyperthermia-susceptible patients, the authors recommend replacing the ventilator diaphragm and integrated breathing system with autoclaved components, flushing the workstation for 5 min at a fresh gas flow of 10 l/min, and maintaining this flow for the duration of anesthesia.