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PubMed1978

Ideas on the suspension of the below-knee prosthesis.

Comparative studies with the PTB-suction prosthesis and the ordinary PTB prosthesis have provided opportunities to analyze and understand some functional differences in the suspension of below-knee prostheses. In a roentgenological study of the stump-socket contact signficantly less vertical displacement in the PTB-suction prosthesis has been shown. A study of the pressure variations in the suction socket verified the theory of the necessary pressure gradient in the PTB-suction socket. Added negative pressure by muscle action was also observed. An electromyographic study suggested a muscular activity pattern in the suction prosthesis similar to that of a normal leg, as a contrast to the ordinary PTB prosthesis where simultaneous contractions of antagonistic muscles seemed to be the usual pattern. The latter is interpreted as a defence reaction. An optimal prosthesis has been deduced. It shall have a soft prosthetic socket with a perfect fit, a suction, adhesion and friction fixation and a pressure gradient between the skin and the socket wall with minimum compression distally. The plaster casting shall be done in a downward modelling manner making available space for soft tissue without compression.

Amputation, Surgical↗
PubMed2005

Role of long stem revision knee prosthesis in periprosthetic and complex distal femoral fractures: a review of eight patients.

Eight patients, six with periprosthetic and two with complex distal femoral fractures (one pathological, and one with failed internal fixation) were treated with a cemented long stem revision arthroplasty prosthesis to address the issues of articular comminution, stability, alignment and early mobilisation. The average age of the patients was 78 years (range 39-81). There were no intra-operative complications. The mean hospital stay was 12 days (range 8-21). Post-operative complications included one case of posterior dislocation and one superficial infection. All patients had remarkable symptomatic relief at 3 months as indicated by the visual analogue scores. All periprosthetic fractures achieved bony union at a mean time of 3.8 months. The mean follow up was 24 months (range 14-42). The American Knee Society score revealed one 'excellent', five 'good', one 'satisfactory' and one 'poor' result. The mean loss of extension was 7.7 degrees (range 5 degrees -15 degrees ) and the mean flexion achieved was 66 degrees (range: 15 degrees to 85 degrees ). The mean alignment was 6 degrees (range 0 degrees -10 degrees ) valgus. This study highlights the role of long stem prosthesis in periprosthetic and some complex distal femoral fractures in offering stability and early mobilisation.

Adult↗
PubMed1995

Arthroplasty with a composite of an allograft and a prosthesis for knees with severe deficiency of bone.

We reviewed the clinical and radiographic results of fourteen patients who had a severe deficiency of bone and were managed with a massive allograft in conjunction with a standard total knee prosthesis between 1987 and 1990. The etiology of the bone loss included the failure of a previous total knee prosthesis, a supracondylar fracture of the femur or a fracture of the proximal part of the tibia, and débridement during the first stage of a reconstruction for the treatment of an infection. Thirteen patients had satisfactory clinical and radiographic results after the index procedure. The knee score of The Hospital for Special Surgery improved from an average of 24 points (range, 0 to 54 points) preoperatively to 82 points (range, 37 to 98 points) at the time of the most recent follow-up examination. The average duration of follow-up was forty-three months (range, twenty-nine to sixty-three months). The radiographic and functional results compare favorably with those that have been reported in most studies of otherwise comparable patients who had less deficiency of bone. While considerable risks are associated with the use of allograft bone and the true longevity of reconstructions with such bone is not yet known, the initial and short-term follow-up results support the use of allograft for the restoration of a functional knee joint in a patient who has a severe deficiency of bone.

Adult↗
PubMed2003

[CT-based and CT-free navigation in knee prosthesis implantation. Results of a prospective study].

INTRODUCTION: Accurate leg alignment is one important factor for long-term survival in total knee arthroplasty (TKA). The classical surgeon-controlled technique is associated with a deviation of the leg axis of more than 3 degrees in up to 30% of cases, regardless of the surgeon's experience. The aim of this study was to test the efficiency of a CT-based and CT-free navigation system in restoration of the leg axis. METHOD: 100 TKA (PFC-Sigma, DePuy) were implanted either using the CT-based or CT-free module of the Vector-Vision navigation System (BrainLAB). There were no significant differences between the groups in preoperative leg deformity. Accuracy of implantation was determined on postoperative long-leg coronal and lateral X-rays. RESULTS: A postoperative leg axis between 3 degrees varus and 3 degrees valgus was obtained in 46 patients (92%) in the CT-based group (A) and in 48 patients (96%) in the CT-free group (B). No significant differences were found for varus / valgus orientation (+/-3 degrees ) of the femoral (A=96%; B=94%) and tibial (A and B each 98%) components. CONCLUSION: The use of the CT-based and CT-free Vector-Vision system allows a significant improvement in the accuracy of implantation in TKA. The CT-based module has the advantage of precise preoperative planning. On the other hand there are additional costs and time-consuming logistics. The advantages of the CT-free module are the intraoperative visualisation of the leg axis, the ligament balancing and joint kinematics. Cutting errors can be detected and corrected with both modules.

Adult↗
PubMedDate not supplied

[Assessment of function recovery in patients with total knee prosthesis].

The aim of this study was to analyse the evolution of motor performance in a group of patients who underwent surgical knee replacement. We also assessed patient satisfaction at 3 and 9 months after the operation. Sixty-two patients (40 women, 22 men, mean age 72.4 years) underwent isokinetic evaluation associated with surface EMG. All the patients had undergone a total prosthetic knee joint replacement for arthrosis, and had followed a standardised 30-day rehabilitation program at our centre for recovery of knee joint function, strengthening of the flexor-extensor muscles and restoration of ambulation as best as possible. Each of these patients underwent isokinetic evaluations 3 months and 9-10 months after their operation. The isokinetic test consisted of carrying out 5 flexion-extensions of the knee at an angular velocity of 60 degrees/second, followed by an endurance test of 30 repetitions of flexion-extension of the knee at 120 degrees/second. This isokinetic test provided data on extensor strength and flexor strength; furthermore, specifically designed software allowed simultaneous visualisation of the surface EMG tracing, torque and joint excursion. The first analysis showed a macroscopic decrease in the strength of the flexor-extensor muscles of the knee. This muscle weakness was clearly evident 3 months after the operation and was particularly pronounced for the extensor muscles of the operated limb compared with the muscles of contralateral, unoperated limb. Muscle weakness was still present 9 months after the operation although there had been a considerable improvement compared with 6 months previously; the imbalance in the flexor/extensor ratio, which differed from that in the contralateral, unoperated limb, was noted to be still present. The surface EMG demonstrated persistent myoelectrical activity in the flexors even when the extensor activity was predominant: this is an expression of imbalance between agonists-antagonists. A questionnaire administered to the patients about their satisfaction with the operation revealed that 9 months after the surgery 23 patients still complained of continuous joint pain with increased loads, 27 complained of frequent pain with load-bearing and only 12 no longer complained of any disturbance, manifesting full satisfaction with the operation. Total knee replacement is thus a valid treatment in those cases in which degenerative joint disease necessitates a radical solution. Nevertheless, dissatisfaction with the operation is common, and may be due to persistence of joint pain and incomplete joint recovery of joint function or muscle strength. In our series of patients, we found that although there was progressive recovery of strength of both the flexor and extensor muscles, a considerable imbalance remained between the operated and unoperated limbs; this finding was also confirmed by the surface EMG investigation.

Aged↗
PubMed1999

[Total knee prosthesis and simultaneous corrective tibial osteotomy, for osteoarthritis and severe congenital tibia varum deformity].

INTRODUCTION: Restoration of the normal mechanical axis of the knee and balancing of the surrounding soft tissues have been shown to have an important bearing on the final outcome of total knee arthroplasty. In knees with severe congenital varum deformity these goals may be difficult to achieve. MATERIAL AND METHODS: In four patients with osteoarthritis and severe congenital knee varum deformity of more than 15 degrees, we performed a high tibial valgus osteotomy with opening wedge, combined during the same procedure with total knee arthroplasty. RESULTS: As correction of the extra-articular deformity was obtained by the osteotomy, in none of the cases it was necessary to perform extensive soft tissue release or advancement to restore alignment. Postoperative X-rays demonstrated restoration of the normal mechanical axis in three cases, but in one case the angular correction of the osteotomy was insufficient and we observed a 9 degrees residual varus deformity. DISCUSSION: The osteoarthritic knee must be mechanically realigned for any total knee arthroplasty to be successful in the long term. Most commonly angular deformities are manifestations of the arthritis process, but sometimes, like in congenital varus deformity of the tibia, part of the deformation can be extra-articular in origin. In these cases, restoring alignment and stability may be difficult to achieve. The association of high tibial valgus osteotomy with total knee arthroplasty permits the correction of the extra-articular deformity, by the osteotomy, without performing extensive soft tissue release, as would be needed in total knee arthroplasty alone. CONCLUSION: Total knee arthroplasty associated with high tibial valgus osteotomy seems to be a technically satisfying alternative in patients with osteoarthritis and severe congenital varus deformity of the tibia.

Aged↗
PubMed2003

The study of metal ion release and cytotoxicity in Co-Cr-Mo and Ti-Al-V alloy in total knee prosthesis - scanning electron microscopic observation.

We surgically retrieved two cobalt(Co)-chromium(Cr)-molybdenum(Mo) and five titanium(Ti)-aluminum(Al)-vanadium(V) alloy knee prostheses from patients because of mechanical failure and pain. We examined the distribution of the small particles which were released from the Co-Cr-Mo and Ti-Al-V alloys using a backscattered scanning electron microscopy (SEM). In addition we analyzed the metals in the artificial knee joints and the tissues adjacent to them using energy dispersive X-ray spectroscopy (EDS). We demonstrated that a myriad of fine particles, produced by the abrasion of both Co-Cr-Mo and Ti-Al-V alloys, accumulated in the synovial cells. As Co-Cr-Mo alloys disintegrate easily in the cells, Co dissolves from the peripheral areas of them, although Cr remains within the cells. In contrast Ti-Al-V alloys are very stable in the synovial cells. From these findings we conclude that the Co-Cr-Mo alloys are hazardous to the body as the alloys release Co which enters the body. In contrast the Ti-Al-V alloys are very stable and are patently safer. Artificial joints, however, are still in considerable need of improvement.

Journal Article↗
PubMed1998

[Deep venous thrombosis (DVT) after hip or knee prosthesis. Evaluation of practices for prevention and prevalence of DVT on doppler ultrasonography].

PURPOSE: Duplex ultrasound scanning was performed to detect deep venous thrombosis (DVT) after hip or knee arthroplasty and evaluate application of the postoperative thromboprophylaxis consensus. PATIENTS AND METHODS: A prospective multicenter study was conducted between April 1995 and April 1996 in 16 centers. Thirty angiologists included 505 patients (370 in private clinics and 135 in university hospitals). Mean patient age was 71 years. There were 288 women. Hip arthroplasty was performed in 396 patients (78%) and knee arthroplasty in 109 (22%), under general anesthesia in 323. The postoperative thromboprophylaxis consensus was recalled prior to study onset and DVT was detected 8 and 10 days after surgery by duplex ultrasonography. RESULTS: Thromboprophylaxis was prescribed by the anesthesiologist (57%), the surgeon (23%) or an angiologist (20%). Anticoagulation dosage was lower than the recommended dosage in 181 patients (36%). The prevalence of detected deep venous thrombosis was 14% (range 11-17%), including 21 cases of proximal DVT (4.2%), 33 of distal DVT (6.5%) and 17 of distal muscular DVT (3.4%). The risk of having a DVT was 1.6-fold higher in patients over 70 years of age (p = 0.04), 2.2-fold higher in case of general anesthesia (p = 0.03) and 2.1-fold higher in case of reduced mobility (p = 0.01). When heparin dosage was lower than the recommended consensus dosage, prevalence of DVT was 19% compared with 11% for patients who received the right dosage (RR = 1.7, p = 0.01). CONCLUSION: Much progress is needed in the application of the postoperative consensus on thromboprophylaxis. The high prevalence of DVT despite preventive treatment indicates that systematic detection of DVT is useful, particularly in high-risk patients or when the recommended thromboprophylaxis cannot be applied.

Adult↗
PubMed2000

Low-conforming all-polyethylene tibial component not inferior to metal-backed component in cemented total knee arthroplasty: prospective, randomized radiostereometric analysis study of the AGC total knee prosthesis.

In a prospective, randomized study of 40 patients, the quality of fixation of cemented metal-backed versus all-polyethylene tibial components of the unconstrained anatomic graduated component total knee arthroplasty design was studied during 2 years using radiostereometric analysis (RSA). The shape, as well as the articulating geometry, of the implants was identical, as was the operative technique and the postoperative regimen. In this study, no negative consequences regarding the quality of fixation using an all-polyethylene tibial component with unconstrained articulating surfaces could be identified. In all aspects, the all-polyethylene tibial components displayed migration on par with, or sometimes lower than, their metal-backed counterparts. The rotations of the all-polyethylene components were equally low as for the metal-backed components, and maximum lift-off was significantly lower than for the metal-backed implants. We could not identify any collapse of the bone at the medial condyle or increased subsidence at the medial part of the tibia or increased rates of radiolucent lines in the knees with all-polyethylene components. All all-polyethylene implants seemed to be stable within the resolution of RSA between 1 and 2 years, a finding known to be of positive prognostic significance regarding future aseptic loosening.

Aged↗
PubMed1998

Confirmation of identity by a metallic knee prosthesis in a severely burnt body.

Confirmation of identification of the deceased may be obtained in several ways. In this case, identification was confirmed by matching the serial numbers on a prosthetic knee joint and co-existing anatomical abnormalities with the joint serial number and X-ray reports in the hospital notes of the suspected victim.

Journal Article↗
PubMedDate not supplied

[Objective assessment of results of special hydrotherapy in inpatient rehabilitation following knee prosthesis implantation].

AIM: Based on our own previous surface EMG investigations (EMG mapping), it has been shown that disturbances in coordination, proprioception and strength measured before and after implantation of a total knee arthroplasty (TKA) can be treated successfully with standard physical therapy during in-patient rehabilitation. The objective of the present study was to evaluate the therapeutic effect of a special type of hydrotherapy. METHOD: 25 patients with TKA were treated for 3 weeks with a standardized hydrotherapy training during in-patient rehabilitation. Several diagnostic methods (EMG mapping, Isokinetics, Ultrasound) were applied to objectify and quantify changes in muscular coordination and strength at 4, 7, and 26 weeks postoperative. These results were compared with the results of 38 TKA patients treated with a "standard rehabilitation program" and with the results of 20 healthy persons. RESULTS: EMG mapping as well as isokinetics and ultrasound permitted an objective characterization of the results. Patients treated with the special hydrotherapy showed greater improvements in the investigated items of coordination and strength than patients treated with the "standard rehabilitation program". For example, in the hydrotherapy group a significantly better contraction capacity of the M. vastus intermedius was measured. The intensive hydrotherapy was tolerated by all patients and reached good acceptance. CONCLUSION: The investigated hydrotherapy technique leads to better muscular coordination and strength, which can provoke a better stabilization of the knee joint. Therefore, the early and intensive application of hydrotherapy for improving coordination and strength in the rehabilitation of patients with total knee arthroplasty is advisable.

Aged↗
PubMed1993

Report on the evaluation of the VA/Seattle below-knee prosthesis.

The Department of Veterans Affairs (VA), Rehabilitation Research and Development (Rehab R&D) Service, Technology Transfer Section (TTS) with collaboration from the Prosthetic and Sensory Aids Service (PSAS) managed clinical trials to evaluate the VA/Seattle Below-Knee (BK) Prosthetic System. The clinical trials were held at the Prosthetic Treatment Center (PTC), VA Medical Center, Hines, Illinois. Five other VA medical centers participated in the outreach program of the trials as satellite stations, with PTC Hines as the central fabrication facility. The VA/Seattle BK system is the first complete prosthetic system designed and developed by the Department of Veterans Affairs. It consists of a socket designed and fabricated using computer-aided, automated technology, and off-the-shelf modular components: a lightweight pylon and an ankle unit, and a lightweight, energy-storing foot. The computer-based socket design software, the modular components, and the prosthetic foot were developed with funds from the VA Rehab R&D Service. The evaluation trials were conducted to determine the efficacy of the VA/Seattle prosthesis, its reliability, and acceptance by veterans. The clinical trials began in April 1991 and were completed in August 1992. Forty-six BK amputee veterans were fitted with the VA/Seattle prosthesis. Their progress with the prosthesis was followed for a period of 6 months and data were gathered at intervals of 2 weeks, 3 months, and 6 months. Forty sets of subject data instruments were collected. In order to maintain the accuracy of the results, TTS used the 22 sets that were complete for data analysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗