Kinematics of medial osteoarthritic knees before and after posterior cruciate ligament retaining total knee arthroplasty

Total knee arthroplasty (TKA) is a widely accepted surgical procedure for the treatment of patients with end‐stage osteoarthritis (OA). However, the function of the knee is not always fully recovered after TKA. We used a dual fluoroscopic imaging system to evaluate the in vivo kinematics of the knee with medial compartment OA before and after a posterior cruciate ligament‐retaining TKA (PCR‐TKA) during weight‐bearing knee flexion, and compared the results to those of normal knees. The OA knees displayed similar internal/external tibial rotation to normal knees. However, the OA knees had less overall posterior femoral translation relative to the tibia between 0° and 105° flexion and more varus knee rotation between 0° and 45° flexion, than in the normal knees. Additionally, in the OA knees the femur was located more medially than in the normal knees, particularly between 30° and 60° flexion. After PCR‐TKA, the knee kinematics were not restored to normal. The overall internal tibial rotation and posterior femoral translation between 0° and 105° knee flexion were dramatically reduced. Additionally, PCR‐TKA introduced an abnormal anterior femoral translation during early knee flexion, and the femur was located lateral to the tibia throughout weight‐bearing flexion. The data help understand the biomechanical functions of the knee with medial compartment OA before and after contemporary PCR‐TKA. They may also be useful for improvement of future prostheses designs and surgical techniques in treatment of knees with end‐stage OA. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:40–46, 2011     

重症患者两种撤机方式的比较

目的 比较SmartCare/PS(SC)和压力支持通气(PSV)模式在重症患者中的撤机效果.方法 将41例行机械通气的重症患者,在满足临床撤机条件后,随机分为SC组(n=21)和PSV组(n=20),分别采用SC和PSV模式撤机.记录撤机时间、总通气时间(TVT)、人工操作次数,以及再插管率、气管切开率、气胸发生率和呼吸机相关肺炎(VAP)发生率.结果 SC组撤机时间、TVT较PSV组明显缩短(P<0.05);SC组人工操作次数较PSV组明显减少(P<0.05);两组再插管率、气管切开率、气胸发生率和VAP发生率差异无统计学意义.结论 SC模式可缩短重症患者的撤机时间、TVT和减轻医务人员工作量.     

Modified total en bloc spondylectomy in thoracic vertebra tumour

Total en bloc spondylectomy (TES) for vertebral tumour was previously reported by Tomita through a single posterior approach using a T-saw. A modified total en bloc spondylectomy (MTES) technique is reported in the present study. The disc puncture needle with a sleeve was used to obliquely puncture from the posterior to the anterior direction. A T-saw was inserted through the sleeve and led out to the operator’s side by the leading clamp. The disc was partially cut with the saw from its medial to lateral aspect. After a spinal fixation rod was applied on the operator’s side, the residual discs on the opposite side were cut as described above. Six patients with thoracic vertebral tumours were operated on using the MTES technique. Five patients showed improvement in their neurological deficits postoperatively. There was no evidence of tumour recurrence at the final follow-up. The MTES is technically feasible with improved practicality and safety.     

Management of Periprosthetic Joint Infection: The More We Learn,the Less We Know

BackgroundDespite the tremendous and long-standing success of total hip arthroplasty and total knee arthroplasty as treatments for end-stage arthritis, periprosthetic joint infection (PJI) remains a rare but feared complication of these procedures.MethodsThis review highlights some of the difficulties inherent to studying PJI. These include the difficulty in powering studies to capture this relatively uncommon complication, as well as the heterogeneity in clinical presentation and manifestations associated with the diagnosis and treatment of PJI.ConclusionWe suggest an algorithm for moving forward with new research in an attempt to answer the challenging questions facing the arthroplasty community regarding PJI.     

Total Hip Arthroplasty With an Uncemented Tapered Femoral Component in Patients Younger than 50 Years

The purpose of the present study was to evaluate the outcome of primary uncemented total hip arthroplasty in patients younger than 50 years using the Taperloc (Biomet, Warsaw, Ind) femoral component. We evaluated 94 hips in 79 patients at a mean follow-up of 16 years (range, 11-18.5 years). The average age of the patients at the time of surgery was 36 years (range, 20-49 years). Three femoral components had been revised, none for aseptic loosening. Complete clinical and radiographic follow-up was obtained on the 91 hips that had not undergone femoral component revision. The mean Harris hip score increased from 54 points (range, 20-72) before surgery to 93 points (range, 68-100) at the time of this review. Radiographically, 89 stems (98%) were determined to have fixation by bone ingrowth, 2 (2%) demonstrated stable fibrous ingrowth, and no femoral component was loose. Distal femoral osteolysis was identified in 1 hip (1%). These findings indicate that excellent clinical and radiographic results can be achieved in young patients with the Taperloc femoral component at a mean follow-up of 16 years.     

Retrieval Analysis of Femoral Zirconium Components in Total Knee Arthroplasty : Preliminary Results

Safety of oxidized zirconium (OxZr) in total knee arthroplasty (TKA) has been supported by biomechanical, clinical, and radiologic data. Retrieved OxZr femoral components and corresponding polyethylene (PE) inserts were examined to rule out patterns leading to early failure. Sixteen retrieved TKA with an OxZr femoral component were included. The PE inlays were analyzed applying an established scoring system for wear and surface damage. Femoral components were screened for scratching, pitting, delamination, and striations. The prostheses were in situ for 16.4 ± 11.9 months. The average wear and damage score for the tibial PE inserts was 36.0 ± 12.7. The average score in the visual analysis of the OxZr femoral components was 1.3 ± 1.3. The data presented in this study did not show major wear of the PE in TKA using OxZr components. In this cohort, there were no failures directly related to this implant.     

Incision Infection With Mycobacterium tuberculosis After Total Hip Arthroplasty Without Any Primary Tuberculosis Focus

We describe a case of a tuberculous abscess unassociated with other clinical features of tuberculosis in a 46-year-old woman with a history of 4 hip surgeries plus total hip arthroplasty (THA) due to developmental hip dislocation. Four months after THA, she developed a collection at the incision site for which specimens produced positive culture findings for Mycobacterium tuberculosis. We could not detect any primary focus of tuberculosis anywhere in the patient's body. We performed soft-tissue debridement and drainage completely above the fascia lata to remove pus. The infection recurred twice despite chemotherapy and the earlier treatment. At a 6-year follow-up examination, there was no sign of either tuberculosis or prosthetic loosening. To our knowledge, this is the first report of localized tuberculous abscess within a THA incision.     

Uncemented Total Knee Arthroplasty: 2-Year Follow-Up of 100 Knees With a Rotating Platform, Cruciate-Retaining Design

Review of the literature shows mixed results regarding uncemented total knee arthroplasty (TKA). To our knowledge, there are no reports of results for uncemented TKA that incorporates a cruciate-retaining and rotating platform design. It is theorized that these design features could decrease the stress at the bone-implant interface. This study reports results on 100 uncemented TKAs at a minimum of 2-year follow-up. Average Knee Society clinical score improved from 52.9 to 95.1; average Knee Society functional score improved from 60.5 to 82.0. Ninety-eight percent of patients had excellent and 2% had good results based on Knee Society scores. There was 99% implant survival; 1 patient required revision of a loose tibial component after a motor vehicle accident. The promising short-term results support the continued use of this implant and suggest a prospective randomized study comparing cemented vs uncemented TKA of this design is warranted.     

The Effect of Total Knee Arthroplasty on Knee Joint Kinematics and Kinetics During Gait

This study determined how total knee arthroplasty (TKA) altered knee motion and loading during gait. Three-dimensional kinematic and kinetic gait patterns of 42 patients with severe knee osteoarthritis were collected 1 week prior and 1-year post-TKA. Principal component analysis extracted major patterns of variability in the gait waveforms. Overall and midstance knee adduction moment magnitude decreased. Overall knee flexion angle magnitude increased due to an increase during swing. Increases in the early stance knee flexion moment and late stance knee extension moment were found, indicating improved impact attenuation and function. A decrease in the early stance knee external rotation moment indicated alteration in the typical rotation mechanism. Most changes moved toward an asymptomatic pattern and would be considered improvements in motion, function, and loading.     

Soft Tissue Tension in Cruciate-Retaining and Posterior-Stabilized Total Knee Arthroplasty

Using a tensor for total knee arthroplasty (TKA) designed to facilitate soft tissue balance measurements with a reduced patellofemoral joint, we intraoperatively compared the soft tissue tension of cruciate-retaining (CR) and posterior-stabilized (PS) TKAs performed at 0°, 10°, 45°, 90°, and 135° of flexion, with the patella both everted and reduced in 40 osteoarthritic patients. Although balance of soft tissue tension with a reduced patella of PS TKA slightly increased in varus from extension to flexion, these values slightly decreased for CR TKA from extension to flexion. Accordingly, we conclude that soft tissue tension patterns differ between everted and reduced patellae, as well as between PS and CR TKA.