To determine the tensile forces across the knee extensor mechanism during walking, in simulated conditions of treatment. Gait analysis of six normal subjects was performed, with full weight bearing unilateral immobilisation of the knee during walking. Measurements were taken without then with a brace, unlocked then locked at 0°, 0-10°, 0-20° and 0-30° of flexion. Mean and maximum knee flexion angles were measured, followed by calculation of the mean and maximum forces across the extensor mechanism during loading, supporting and propulsion phases of gait.Aim
Methods
This study was undertaken to evaluate the early results of a new implant system - the metaphyseal sleeve - in revision total knee replacement. The femoral and tibial metaphyseal sleeves are a modular option designed to deal with metaphyseal bone loss and achieve cementless fixation over a relatively wide area in the metaphysis. Over three years, femoral and/or tibial metaphyseal sleeves were implanted in 104 knees in 103 patients (54 male and 49 female). The clinical notes and radiographs of these patients were reviewed retrospectively. Thirty one patients had revision for infection, 42 for aseptic loosening, and 31 for instability, pain or stiffness. Eighty nine knees were revised as a single stage and 15 were done as two stage procedure. Minimum follow up is 12 months (average 18.5 months).Purpose of the study
Methods
This review summarises the opinions and conclusions
reached from a symposium on infected total knee replacement (TKR)
held at the British Association of Surgery of the Knee (BASK) annual
meeting in 2011. The National Joint Registry for England and Wales
reported 5082 revision TKRs in 2010, of which 1157 (23%) were caused
by infection. The diagnosis of infection beyond the acute post-operative
stage relies on the identification of the causative organism by
aspiration and analysis of material obtained at arthroscopy. Ideal
treatment then involves a two-stage surgical procedure with extensive
debridement and washout, followed by antibiotics. An articulating
or non-articulating drug-eluting cement spacer is used prior to
implantation of the revision prosthesis, guided by the serum level
of inflammatory markers. The use of a single-stage revision is gaining popularity
and we would advocate its use in certain patients where the causative
organism is known, no sinuses are present, the patient is not immunocompromised,
and there is no radiological evidence of component loosening or
osteitis. It is our opinion that single-stage revision produces high-quality
reproducible results and will soon achieve the same widespread acceptance
as it does in infected hip arthroplasty.
Avascular meniscal tears can be repaired with good clinical outcomes. The mechanical disadvantage and detrimental effect to articular cartilage following meniscectomy has been well documented in the literature. Meniscal repair in the avascular (white on white zone) is controversial and would be deemed inappropriate by many.Hypothesis
Background
This is a study of the quality of outcome of the first 100 patients who received the Twin Peg Oxford Partial knee replacement; which has been designed with a 15 degree extra surface for contact in deep flexion, and two pins for more secure fixation. We measured the outcome in patients with anteromedial osteoarthritis at 2 years after implantation using patient perception outcome measures: the OKS (Oxford Knee Score) and a patient satisfaction questionnaire. We also measured range of motion, the AKS (American Knee Society Score-Objective), the AFS (American Knee Society Score-Functional), and carried out a radiological assessment. The results showed a mean OKS of 41, a mean AKS of 93, a mean AFS of 84, a mean range of motion of 130 degrees and a 97% satisfaction rate. Results were significantly better in male patients. There were no deaths, infections, dislocations, fractures or revisions. There were no radiolucent lines of 2 mms or more at the femoral bone-cement interfaces. The introduction of this new version of the Oxford knee shows excellent clinical and radiological results which are at least as good as those seen with the Phase 3 Oxford Partial knee replacement. Small adjustments were made to the minimally invasive approach: a reduced invasive incision for ease of implantation. For those surgeons who are concerned over the risks of femoral loosening with the Phase 3 implant, or desire an improved surface area of contact at high angles of flexion, this Twin Peg Oxford Partial knee replacement offers an excellent alternative.
Simultaneous bilateral Total Knee Arthroplasty (TKA) has been reported to bring greater patient satisfaction, reduce in-patient stay and recovery, with similar outcomes to single sided or staged TKA, but higher complication rates. No validated selection criteria exist. We report the results of a single surgeon's experience of simultaneous bilateral TKA, using set guidelines for patient selection. A prospectively maintained database of all simultaneous bilateral TKA performed between 2002 and 2008 was retrospectively analysed, supplemented by case-note review. Outcome measures included length of stay, blood loss and transfusion rates, complications and functionality and validated outcome scores. 40 patients were included, 23 male and 17 female, all with osteoarthritis. Mean age was male 64.9 and female 61.3 years. Mean ASA grade was 1.8. All fitted selection criteria. Mean tourniquet time was right 79.1 minutes and left 83.6 minutes. Preoperative mean haemoglobin level was 141.8 g/dl and mean post operative level of 87.3 g/dl. 13 patients received purely autologous blood transfusion, 16 patients purely allogenic and 6 patients received both. There was 1 intraoperative complication (Medial collateral injury), 3 minor post operative complications which recovered prior to discharge. There were no thromboembolic events or deaths. Mean follow-up was 32.7 months (range 3-79 months). Mean in-patient stay was 7.5 days. Mean range of movement at most recent follow up was right 1.0 to 119.1 degrees flexion and left 1.0 to 120.8 degrees flexion. Mean Knee Society Scores pre- versus post-operatively were: 67 knee/62 function versus 90 knee/82 function. Oxford Knee Scores, Pre- versus post-operatively were: 43 versus 35 (Scoring 0-60, lowest best outcome). We demonstrate that with appropriate selection criteria, simultaneous bilateral TKA is safe and successful, giving excellent functional outcomes.
The administration of intra-articular local anaesthetic is common following arthroscopy of the knee. However, recent evidence has suggested that bupivacaine may be harmful to articular cartilage. This study aimed to establish whether infiltration of bupivacaine around the portals is as effective as intra-articular injection. We randomised 137 patients to receive either 20 ml 0.5% bupivacaine introduced into the joint (group 1) or 20 ml 0.5% bupivacaine infiltrated only around the portals (group 2) following arthroscopy. A visual analogue scale was administered one hour post-operatively to assess pain relief. Both patients and observers were blinded to the treatment group. A power calculation was performed. The mean visual analogue score was 3.24 ( Infiltration of bupivacaine around the portals had an equivalent effect on pain scores at one hour, and we would therefore recommend this technique to avoid the possible chondrotoxic effect of intra-articular bupivacaine.
We describe the influence of the angle of immobilisation during partial weight-bearing on the forces across the extensor mechanism of the knee. Gait analysis was performed on eight healthy male subjects with the right knee in an orthotic brace locked at 0°, 10°, 20° and 30°, with the brace unlocked and also without a brace. The ground reaction force, the angle of the knee and the net external flexion movement about the knee were measured and the extensor mechanism force was calculated. The results showed a direct non-linear relationship between the angle of knee flexion and the extensor mechanism force. When a brace was applied, the lowest forces occurred when the brace was locked at 0°. At 30° the forces approached the failure strength of some fixation devices. We recommend that for potentially unstable injuries of the extensor mechanism, when mobilising with partial weight-bearing, the knee should be flexed at no more than 10°.
We present a series of 48 patients with infected total knee replacements managed by the use of articulating cement spacers and short-term parenteral antibiotic therapy in the postoperative period. All patients had microbiological and/or histological confirmation of infection at the first stage of their revision. They all underwent re-implantation and had a mean follow-up of 48.5 months (26 to 85). Infection was successfully eradicated in 42 of the 48 patients (88%). Six had persistent infection which led to recurrence of symptoms and further surgery was successful in eliminating infection in four patients. These rates of success are similar to those of other comparable series. We conclude that protracted courses of intravenous antibiotic treatment may not be necessary in the management of the infected total knee replacement. In addition, we analysed the microbiological, histological and serological results obtained at the time of re-implantation of the definitive prosthesis, but could not identify a single test which alone would accurately predict a successful outcome.
In this cross-over study, we evaluated two types of knee brace commonly used in the conservative treatment of osteoarthritis of the medial compartment. Twelve patients confirmed radiologically as having unilateral osteoarthritis of the medial compartment (Larsen grade 2 to grade 4) were studied. Treatment with a simple hinged brace was compared with that using a valgus corrective brace. Knee kinematics, ground reaction forces, pain and function were assessed during walking and the Hospital for Special Surgery scores were also determined. Significant improvements in pain, function, and loading and propulsive forces were seen with the valgus brace. Treatment with a simple brace showed only significant improvements in loading forces. Our findings suggest that although both braces improved confidence and function during gait, the valgus brace showed greater benefit.
Clinical experience of impaction bone grafting for revision knee arthroplasty is limited, with initial stability of the tibial tray emerging as a major concern. The length of the stem and its diameter have been altered to improve stability. Our aim was to investigate the effect of the type of stem, support of the rim and graft impaction on early stability of the tray. We developed a system for impaction grafting of trays which we used with morsellised bone in artificial tibiae. Trays with short, long thick or long thin stems were implanted, with or without support of the rim. They were cyclically loaded while measuring relative movement. Long-stemmed trays migrated 4.5 times less than short-stemmed trays, regardless of diameter. Those with support migrated 2.8 times less than those without. The migration of short-stemmed trays correlated inversely with the density of the impacted groups. That of impaction-grafted tibial trays was in the range reported for uncemented primary trays. Movements of short-stemmed trays without cortical support were largest and sensitive to the degree of compaction of the graft. If support of the rim was sufficient or a long stem was used, impacted morsellised bone graft achieved adequate initial stability.
We undertook a prospective, randomised study of 135 total knee arthroplasties to determine the most accurate and reliable technique for alignment of the tibial prosthesis. Tibial resection was guided by either intramedullary or extramedullary alignment jigs. Of the 135 knees, standardised postoperative radiographs suitable for assessment were available in 100. Correct tibial alignment was found in 85% of the intramedullary group compared with 65% of the extramedullary group (p = 0.019). We conclude that intramedullary guides are superior to extramedullary instruments for alignment of the tibial prosthesis.
There is a need for the accurate measurement of the outcome after knee surgery. The Oxford Knee Score is being increasingly used since it is reported to be short, simple, inexpensive and validated. We sent the questionnaire to 346 patients awaiting surgery to the hip or lumbar spine. Only 11% of 141 patients with proximal pathology who denied knee problems gave a maximum score. Their mean score was substantially lower than expected at 28.7 (maximum 48), and was significantly lower than the score of 36.5 obtained from patients after total knee replacement. We therefore suggest that the frequent coexistence of hip or spinal pathology will significantly alter both the absolute score and any improvement to be expected after knee surgery. Although sensitive to disability originating from the knee the Oxford Knee Score is not sufficiently specific since it is heavily influenced by more proximal pathology.
Thirty cruciate ligaments were retrieved from either cadavers or limbs which had been amputated. Each specimen was sectioned and stained to demonstrate the presence of collagen, nerves and vessels. All 30 specimens contained an interconnecting band of collagen fibres between the anterior and posterior cruciate ligaments. Vascular structures were present in all specimens and nerve fibres were identified in 26 (86%). We have called this structure the ‘intercruciate band’. The anterior and posterior cruciate ligaments should no longer be thought of in isolation, but together as a ‘cruciate complex’.
