A.H. Deakin

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.

Comparative Analysis of the Structural Properties of the Collateral Ligaments of the Human Knee

STUDY DESIGN Controlled laboratory study. BACKGROUND Varus knee instability arising from lateral collateral ligament (LCL) injury increases stress on cruciate ligament grafts, potentially leading to failure of reconstructed ligaments. In contrast to the medial collateral ligament (MCL), little is known about the structural properties of the LCL. OBJECTIVES To compare the tensile properties of the LCL and MCL complex of the human knee joint. METHODS Ten fresh-frozen cadaveric knees (mean ± SD age, 81 ± 11 years), free of gross musculoskeletal pathology, were obtained. Following dissection, the length, width, and thickness of the ligaments were measured using calipers, and bone-ligament-bone preparations were mounted in a uniaxial load frame. After preconditioning, specimens were extended to failure at a rate of 500 mm/min (approximately 20%/s). Force and crosshead displacement were used to calculate structural properties, including stiffness, yield strength, ultimate tensile strength, and failure energy. RESULTS The fan-shaped MCL was significantly longer (60%; P<.001), wider (680%; P<.001), and thinner (19%; P = .009) than the cord-like LCL. The LCL failed at either the fibular attachment (n = 6) or midsubstance (n = 4), while failure of the MCL primarily occurred at the femoral attachment (n = 7). Although the ultimate tensile strength of the MCL (mean ± SD, 799 ± 209 N) was twice that of the LCL (392 ± 104 N; P<.001), there was no significant difference in stiffness of the ligaments (MCL, 63 ± 14 N/mm; LCL, 59 ± 12 N/mm). CONCLUSIONS Despite differences in geometry and strength, there was no significant difference in stiffness of the MCL and LCL when tested in vitro.

A comparison of radiological and computer navigation measurements of lower limb coronal alignment before and after total knee replacement

We compared lower limb coronal alignment measurements obtained pre- and post-operatively with long-leg radiographs and computer navigation in patients undergoing primary total knee replacement (TKR). A series of 185 patients had their pre- and post-implant radiological and computer-navigation system measurements of coronal alignment compared using the Bland-Altman method. The study included 81 men and 104 women with a mean age of 68.5 years (32 to 87) and a mean body mass index of 31.7 kg/m(2) (19 to 49). Pre-implant Bland-Altman limits of agreement were -9.4° to 8.6° with a repeatability coefficient of 9.0°. The Bland-Altman plot showed a tendency for the radiological measurement to indicate a higher level of pre-operative deformity than the corresponding navigation measurement. Post-implant limits of agreement were -5.0° to 5.4° with a repeatability coefficient of 5.2°. The tendency for valgus knees to have greater deformity on the radiograph was still seen, but was weaker for varus knees. The alignment seen or measured intra-operatively during TKR is not necessarily the same as the deformity seen on a standing long-leg radiograph either pre- or post-operatively. Further investigation into the effect of weight-bearing and surgical exposure of the joint on the mechanical femorotibial angle is required to enable the most appropriate intra-operative alignment to be selected.

Blood loss following total knee replacement in the morbidly obese: Effects of computer navigation

Computer navigated total knee arthroplasty (TKA) has several proposed benefits including reduced post-operative blood loss. We compared the total blood volume loss in a cohort of morbidly obese (BMI>40) patients undergoing computer navigated (n=30) or standard intramedullary techniques (n=30) with a cohort of matched patients with a BMI<30 also undergoing navigated (n=31) or standard TKA (n=31). Total body blood loss was calculated from body weight, height and haemotocrit change, using a model which accurately assesses true blood loss as was maximum allowable blood loss which represents the volume of blood that can be lost until a transfusion trigger is required. The groups were matched for age, gender, diagnosis and operative technique. The mean true blood volume loss across all BMIs was significantly (p<0.001) less in the computer assisted group (1014±312ml) compared to the conventional group (1287±330ml). Patients with a BMI>40 and a computer navigated procedure (1105±321ml) had a significantly lower (p<0.001) blood volume loss compared to those who underwent a conventional TKA (1399±330ml). There was no significant difference in the transfusion rate or those reaching the maximum allowable blood loss between groups. This study confirms a significant reduction in total body blood loss between computer assisted and conventional TKA in morbidly obese patients. However computer navigation did not affect the transfusion rate or those reaching the transfusion trigger in the morbidly obese group. Therefore computer navigation may reduce blood loss in the morbidly obese patient but this may not be clinically relevant to transfusion requirements as previously suggested.

Using navigation intraoperative measurements narrows range of outcomes in TKA

Computer-assisted technology creates a new approach to total knee arthroplasty (TKA). The primary purpose of this technology is to improve component placement and soft tissue balance. We asked whether the use of navigation techniques would lead to a narrow range of implant alignment in both coronal and sagittal planes and throughout the flexion-extension range. Using a prospective consecutive series of 57 navigated TKAs, we assessed intraoperative knee measurements, including alignment, varus-valgus stress angles in extension, and varus-valgus angles from 0° to 90° of flexion comparing postimplant with preimplant. We found fewer outliers with coronal (100% of TKAs within ±2°) and sagittal (0% of TKAs with fixed flexion greater than 5°) alignment, soft tissue balancing (mean varus and valgus stress angles −3.2° and 2.3°; range, −5° to 5°), and mean femorotibial angle over flexion range 0° (−0.2°; range, −1° to 2°), 30° (−0.2°; range, −5° to 4°), 60° (−0.5°; range, −5° to 7°), and 90° (−0.2°; range, −5° to 10°). This technology allows a narrow range of implant placement and soft tissue management in extension. We anticipate improved ultimate patient outcomes with less tissue disruption.Level of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Computer navigated total knee arthroplasty: the learning curve.

The learning curve for computer navigated total knee arthroplasty (TKA) is not well defined. We collected data prospectively on a consultant surgeons first 50 navigated TKAs. Over the same period, matching data was taken from 50 consecutive cases performed by an expert who has performed over 1000 navigated TKAs. From the first case, the novice navigator was able to achieve the same standard as the expert in terms of post-implant mechanical alignment in the coronal and sagittal planes. Equally, at 6 weeks and one year post-surgery there was no significant difference in the mean Oxford score, mechanical axis and range of movement for the two groups of patients. Operative time was significantly longer for the novice surgeon in the first 20 cases (92 versus 73 min, p < 0.001), but by the final 20 cases there was no difference (72 versus 74 min, p = 0.944). This study shows that the learning curve for navigated TKA is approximately 20 cases and that a beginner can reproduce the results of an expert from the outset.

Flexion contracture following primary total knee arthroplasty: risk factors and outcomes.

Function and satisfaction after total knee arthroplasty (TKA) are partially linked to postoperative range of motion (ROM). Fixed flexion contracture is a recognized complication of TKA that reduces ROM and is a source of morbidity for patients. This study aimed to identify preoperative risk factors for developing fixed flexion contracture following TKA and to quantify the effect of fixed flexion contracture on outcomes (Oxford knee score 12-60 and patient satisfaction) at 2 years. Pre-, intra-, and postoperative data for 811 TKAs were retrospectively reviewed. At 2 years postoperatively, the incidence of fixed flexion contracture was 3.6%. Men were 2.6 times more likely than women to have fixed flexion contracture (P=.012), and patients with preimplant fixed flexion contracture were 2.3 times more likely than those without to have fixed flexion contracture (P=.028). Increasing age was associated with an increased rate of fixed flexion contracture (P=.02). Body mass index was not a risk factor (P=.968). Incidence of fixed flexion contracture for those undergoing computer navigated TKA was 3.9% compared with 3.4% for those having conventional surgery (P=.711). Patients with fixed flexion contracture had poorer outcomes with a median [interquartile range] Oxford Knee Score of 25 [15] compared with 20 [11] for those without (P=.003) and lower patient satisfaction (P=.036). These results support existing literature for incidence of fixed flexion contracture after TKA, risk factors, and outcomes, indicating that these figures can be extrapolated to a wide population. They also clarify a previously contentious point by excluding body mass index as a risk factor.

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.