A.W.G. Kinninmonth

Femoral nerve block for total knee replacement — A word of caution

Femoral nerve block (FNB) is a well documented option for post-operative analgesia following major knee surgery. However, motor blockade may be prolonged preventing early mobilisation thereby increasing the length of stay. In addition, as a consequence of persistent quadriceps weakness, patients have an increased risk of falling. We present a series of five patients who underwent total knee replacement with spinal anaesthesia and FNB who fell, sustaining complete wound disruption - including a patient with peri-prosthetic fracture requiring further surgery and prolonged hospital stay. The literature, which is largely in anaesthetic journals, reflects the high quality of analgesia of FNB but makes little or no mention of the delays or dangers in early mobilization. We believe that the potential risks to orthopaedic patients are underestimated.

An enhanced recovery programme for primary total knee arthroplasty in the United Kingdom--follow up at one year.

The concepts of Enhanced Recovery Programmes (ERP) are to reduce peri-operative morbidity whilst accelerating patients rehabilitation resulting in a shortened hospital stay following primary joint arthroplasty. These programmes should include all patients undergoing surgery and should not be selective. We report a consecutive series of 1081 primary total knee arthroplasties undergoing an enhanced recovery programme with a one year follow up period. A comparative cohort of 735 patients from immediately prior to the enhanced recovery programme implementation was also reviewed. The median day of discharge home was reduced from post-operative day six to day four (p<0.001) for the ERP group. Post-operative urinary catheterisation (35% vs. 6.9%) and blood transfusion (3.7% vs. 0.6%) rates were significantly reduced (p<0.001). Within the ERP group median pain scores (0 = no pain, 10 = maximal pain) on mobilisation were three throughout hospital stay with 95% of patients ambulating within 24h. No statistical difference was found in post-operative thrombolytic events (p=0.35 and 0.5), infection (p=0.86), mortality rates (p=0.8) and Oxford Knee Scores (p=0.99) at follow up. This multidisciplinary approach provided satisfactory post-operative analgesia allowing early safe ambulation and expedited discharge to home with no detriment to continuing rehabilitation, infection or complication rates at one year.

Reduction of blood loss in primary hip arthroplasty with tranexamic acid or fibrin spray.

Background and purpose Previous studies have shown that either fibrin spray or tranexamic acid can reduce blood loss at total hip replacement, but the 2 treatments have not been directly compared. We therefore conducted a randomized, controlled trial. Patients and methods In this randomized controlled trial we compared the effect of tranexamic acid and fibrin spray on blood loss in cemented total hip arthroplasty. 66 patients were randomized to 1 of 3 parallel groups receiving (1) a 10 mg/kg bolus of tranexamic acid prior to surgery, (2) 10 mL of fibrin spray during surgery, or (3) neither. All participants except the surgeon were blinded as to treatment group until data analysis was complete. Blood loss was calculated from preoperative and postoperative hematocrit. Results Neither active treatment was found to be superior to the other in terms of overall blood loss. Losses were lower than those in the control group, when using either tranexamic acid (22% lower, p = 0.02) or fibrin spray (32% lower, p = 0.02). Interpretation We found that the use of tranexamic acid at induction, or topical fibrin spray intraoperatively, reduced blood loss compared to the control group. Blood loss was similar in the fibrin spray group and in the tranexamic acid group. ClinicalTrials.gov identifier: NCT00378872 EudraCT identifier: 2006-001299-19 Regional Ethics Committee approval: 06/S0703/55, granted June 6, 2006

Reducing blood loss in primary knee arthroplasty: a prospective randomised controlled trial of tranexamic acid and fibrin spray.

A prospective, randomised controlled trial compared the effects of two medications intended to reduce blood loss from total knee arthroplasty. Patients were randomised to one of the following three treatment groups: 10mg/kg tranexamic acid at given at induction of anaesthesia, 10 ml of fibrin spray administered topically during surgery, or to a control group receiving neither treatment. Sixty six patients underwent elective cemented total knee arthroplasty; computer navigation was used in all cases. There was no significant difference in blood loss between the tranexamic acid and fibrin spray groups (p=0.181). There was no significant difference in blood loss between the tranexamic acid and fibrin spray groups(p=0.181). The fibrin spray led to a significant reduction in blood loss compared to control (p=0.007). The effect of tranexamic acid did not reach significance (p=0.173). We conclude that fibrin spray was effective in reducing blood loss but that with a study of this power, we were unable to detect an effect of tranexamic acid in cemented navigated total knee replacement at the dose used.

A quantitative method of effective soft tissue management for varus knees in total knee replacement surgery using navigational techniques.

Abstract Total knee replacement (TKR) has become the standard procedure in management of degenerative joint disease with its success depending mainly on two factors: three-dimensional alignment and soft-tissue balancing. The aim of this work was to develop and validate an algorithm to indicate appropriate medial soft tissue release during TKR for varus knees using initial kinematics quantified via navigation techniques. Kinematic data were collected intra-operatively for 46 patients with primary end-stage osteoarthritis undergoing TKR surgery using a computer-tomography-free navigation system. All patients had preoperative varus knees and medial release was made using the surgeons experience. Based on these data an algorithm was developed. This algorithm was validated on a further set of 35 patients where it was used to define the medial release based on the kinematic data. The post-operative valgus stress angles for the two groups were compared. These results showed that the algorithm was a suitable tool to indicate the type of medial release required in varus knees based on intra-operatively measured pre-implant valgus stress and extension deficit angles. It reduced the percentage of releases made and the results were more appropriate than the decisions made by an experienced surgeon.

Hip–Knee–Ankle Radiographs Are More Appropriate for Assessment of Post-Operative Mechanical Alignment of Total Knee Arthroplasties than Standard AP Knee Radiographs

Weight-bearing hip-knee-ankle (HKA) radiographs are the gold standard for measuring lower limb alignment after total knee arthroplasty (TKA), however the majority of UK units use standardised anteroposterior (AP) knee radiographs. This study aimed to determine whether standardised AP knee radiographs adequately assess lower limb alignment after TKA. HKA radiographs from 50 post-operative TKAs were cropped to the size of a standardised AP knee radiograph allowing comparison of mechanical and anatomical alignment measurements between the two views. Repeatability of alignment measurements was significantly better for HKA radiographs, however, there was poor agreement of the mechanical alignment measured between the two views. Standardised AP knee radiographs are insufficient to assess the mechanical alignment of post-operative TKA and we recommend routinely using HKA radiographs.

Intra-operative deviation in limb alignment occurring at implantation in total knee arthroplasty

BACKGROUND Long-term survival of knee replacement depends on accurate alignment. Despite improvements in cut accuracy mal-alignment of 3° or more is still seen. All methods share common implantation techniques. This study examines the effect of implantation on overall limb alignment relating it to cut alignment and trial alignment. METHODS A retrospective review of navigated primary knee replacements was undertaken (n=113). Overall coronal limb alignments for the aggregated cuts, trial and final implanted components were examined. RESULTS All 113 knees had coronal aggregated cut alignment within 2° of neutral (range: 2° varus to 2° valgus). With trial components 99 knees (88%) had an overall coronal limb alignment within 2° of neutral (range: 3° varus to 4° valgus). After final implantation 106 knees (94%) were within 2° of neutral (range: 4° varus to 4° valgus). Forty eight knees (42%) showed no alignment deviation occurring between trial and the final implanted prostheses and 16 knees (14%) shoed a deviation of 2° or more. There was a correlation of both aggregated cut (r=0.284, p=0.002) and trial (r=0.794, p<0.001) with final alignment. There was no significant difference between the final alignment and the aggregated cut alignment(mean difference=-0.15°, p=0.254) or trial alignment (mean difference -0.13°, p=0.155). CONCLUSIONS Even when the aggregated alignment produced by the bone cuts is accurate, inaccuracy in final alignment can result from the implantation process. It may be productive for surgeons to concentrate on the implantation process to improve alignment and reduce outliers.

The efficacy and safety of epidural filter catheters when used for post-operative intra-articular anaesthesia.

UNLABELLED There are concerns about the risk of iatrogenic infection when employing local anaesthetic techniques with post-operative intra-articular infusions in total knee arthroplasty. This study aimed to determine the efficacy of intact epidural filters in preventing transit of bacteria and to develop a technique of administration which would prevent membrane rupture. Filter efficacy was assessed using a standardised test suspension of Pseudomonas aeruginosa. Twenty millilitres of suspension was injected through isolated epidural filters (n=10) or filters with 40cm of catheter tubing attached (n=30). For each filter, injections were carried out at 0, 8 and 24h. Filtrates were collected, incubated, sub-cultured onto Columbia horse blood agar and examined for bacterial growth. Three delivery techniques were tested: manually controlled syringe with 5ml of water at 20ml/min, forced administration syringe with 5ml of water at >240ml/min and an automated syringe driver delivering 40ml of water at 6.7ml/min. For the two techniques using syringes, three syringe sizes, 5ml, 10ml and 20ml, were tested. Each test condition was carried out on 10 filters (total n=70). Filters were examined for rupture. Intact epidural filters prevented bacterial transit in all cases. Manual controlled and automated syringe driver administration generated no filter ruptures. Manual forced administration generated 93% filter rupture. Ruptures occurred at peak pressures of approximately 620kPa. Epidural filters can be used to prevent bacterial transit. These results suggest automated devices remove the risk of filter rupture. This study is relevant to all specialties that utilise these filters during infiltration such as epidurals or other regional anaesthetic techniques. CLINICAL RELEVANCE This study identified that filters are prone to rupture with high infusion rates and that manual techniques are particularly vulnerable. From these results, it is recommended that pumps are used to minimise risk of filter rupture.