Review article: knee flexion after total knee arthroplasty

Influence of Joint Line Level on Clinical Outcomes and Range of Motion in Total Ankle Arthroplasty

BACKGROUND

Ankle arthritis leads to an elevated joint line compared to the nonarthritic ankle, as measured by the "joint line height ratio" (JLHR). Previous work has shown that the JLHR may remain elevated after total ankle arthroplasty (TAA). However, the clinical impact of this has yet to be determined. This study assessed the correlation between postoperative JLHR, post-TAA range of motion (ROM), and 1-year Patient-Reported Outcome Measurement Information System (PROMIS) scores.

METHODS

A retrospective review of 150 patients who underwent primary TAA was performed. Preoperative and postoperative JLHR, as well as postoperative dorsiflexion, plantarflexion, and total ROM, was calculated on weightbearing radiographs at a minimum of 1-year follow-up. Correlation between JLHR, post-TAA ROM, and 1-year PROMIS scores was investigated using Pearson correlation and multiple linear regression models. Interobserver reliability for the JLHR was also calculated.

RESULTS

Interobserver reliability for the JLHR was excellent (r = 0.98). Mean (SD) JLHR changed from 1.66 (0.45) to 1.55 (0.26) after TAA (P < .001), indicating that the joint line was lowered after TAA. An elevated joint line was correlated with decreased post-TAA dorsiflexion (r = -0.26, P < .001), total ROM (r = -0.18, P = .025), and worse 1-year PROMIS physical function (r = -0.22, P = .046), pain intensity (r = 0.22, P = .042), and pain interference (r = 0.29, P = .007). There was no correlation between the JLHR and post-TAA plantarflexion (r = -0.025, P = .76). Regression analysis identified a 0.5-degree reduction in post-TAA dorsiflexion with each 0.1-unit increase in JLHR (Coeff. = -5.13, P = .005).

CONCLUSION

In this patient cohort, we found that an elevated joint line modestly correlated with decreased postoperative dorsiflexion, total ROM, and worse 1-year PROMIS scores. These data suggest that effort likely should be made toward restoring the native joint line at the time of TAA. In addition, future studies investigating the clinical outcomes after TAA may consider including a measure of joint line height, such as the JLHR, because we found it was associated with patient-reported outcomes.

LEVEL OF EVIDENCE

Level III, retrospective review of prospectively collected data.

Resection of Infrapatellar Fat Pad during Total Knee Arthroplasty Has No Impact on Postoperative Function, Pain and Sonographic Appearance of Patellar Tendon

Routine resection of the infrapatellar fat pad (IFP) during total knee arthroplasty (TKA) is controversial, as it may result in shortening of the patellar tendon (PT) and anterior knee pain. This prospective study examined whether IFP excision during TKA affects joint function, anterior knee pain, PT dimensions and sonographic structure. A total of 65 consecutive patients undergoing TKA for osteoarthritis were randomized into two groups: IFP was resected in one and retained in the other. Patients were examined preoperatively, at 6 weeks and 6 months postoperatively: pain (Numerical Rating Scale-NRS), range of motion (ROM) and knee function (Knee Injury and Osteoarthritis Outcome Score-KOOS score) were evaluated; sonographic examination determined the length, structure and vascularity of the PTs. In both groups there were postoperative improvements in NRS and KOOS scores, although IFP resection did not influence clinical outcomes or sonographic parameters. At 6 weeks and 6 months postoperatively for both groups there were no differences between NRS scores (Mann-Whitney test, p = 0.511 and p = 0.579), ROM scores (Mann-Whitney test, p = 0.331, p = 0.180) or all KOOS subscores. IFP excision had no effect on sonographic parameters. This study suggests that IFP resection during TKA does not influence postoperative functional outcomes, pain scores, patellar tendon length and thickness, or sonographic structure.

Equal bony resection of distal and posterior femur will lead to flexion/extension gap inequality in robot-assisted cruciate-retaining TKA

PURPOSE

Joint imbalance has become one of the main reasons for early revision after total knee arthroplasty (TKA) and it is directly related to the surgical technique. Therefore, a better understanding of how much bone has to be removed to obtain a balanced flexion/extension gap could improve current practice. The primary objective of this study was to analyse the amount of bone that needed to be removed from the distal and posterior femoral joint surfaces to obtain an equal flexion/extension gap in robot-assisted TKA. The second objective of this study was to evaluate whether the size of the knee joint influenced the amount of bony resection needed to achieve an equal flexion/extension gap in robot-assisted TKA.

METHODS

A retrospective analysis was performed on all patients receiving a robot-assisted TKA (Cruciate Retaining (n = 268)) by six surgeons from April 2018 to September 2019. The robot was used consecutively when available in all patients receiving Cruciate Retaining TKA. Gap assessment, bony resections, femoral implant size and hip-knee-ankle angle were evaluated with the robot. Femoral implant size was categorized into small (size 1-2), medium (size 3-5) and large (size 6-8).

RESULTS

The difference between the posterior and distal resection needed to obtain equal flexion and extension gap was on average 2.0 mm (SD 1.6) and 1.5 mm (SD 2.2) for the medial and lateral compartment, respectively. The discrepancy was smaller in the large implant group compared to the small implant group (p < .05 medial and lateral) and medium implant group (p < .05 medial). Varus knees required a larger differential resection compared to neutral and valgus knees (only laterally) (medial compartment: p < .05 (varus-neutral), p = .051 (varus-valgus); lateral compartment: p < .05 (varus-neutral and varus-valgus).

CONCLUSION

Removing an equal amount of bone from the distal and posterior femur will lead to flexion/extension gap imbalance in TKA. It was required to remove 1.5-2 mm more bone from the posterior femur compared to the distal femur to equalize flexion and extension gap. This effect was size dependent: in larger knees, the discrepancy between the distal and posterior resections was smaller.

LEVEL OF EVIDENCE

IV.

[Surgical planning and mid-term effectiveness of four major lower extremity arthroplasties in patients with rheumatoid arthritis]

Objective

To investigate the surgical planning and the mid-term effectiveness of four major lower extremity arthroplasties (4JA) in patients with rheumatoid arthritis (RA).

Methods

A clinical data of 25 patients with RA, who received 4JA and were followed up more than 3 years between June 2012 and September 2018, was retrospectively analyzed. There were 3 males and 22 females, with an average age of 48.6 years (range, 27-80 years). The body mass index ranged from 16.0 to 28.4 kg/m 2, with an average of 20.48 kg/m 2. The duration of RA ranged from 2 to 35 years (median, 21 years). There were 8 cases (12 sides) of knee valgus, 6 cases (12 side) of acetabular retraction, and 5 cases (10 sides) of hip stiffness. Among them, 20 patients underwent hip surgery first, and 5 patients underwent knee surgery first. Hip joint function was evaluated by Harris score, Hip Disability and Osteoarthritis Outcome Score (HOOS), hip range of motion, and Trendelenburg sign; knee joint function was evaluated by American Hospital for Special Surgery (HSS) score, knee range of motion and muscle strength, and a timed up and go (TUG) test was performed at last follow-up. X-ray films were used to observe whether the prosthesis was loose or displaced.

Results

All 25 patients completed 4JA. Only 1 patient (1 side) had incision infection after operation, 3 patients (3 sides) had proximal femur fractures during operation. All patients were followed up 3.0-8.8 years, with an average of 5.8 years. At last follow-up, the Harris score, HOOS score, and range of motion of flexion, extension, and abduction of the hip joint significantly improved when compared with those before operation, and the patients with positive Trendelenburg sign decreased. The HSS score and range of motion of flexion and extension of the knee joint also significantly improved when compared with those before operation. There were significant differences in all indexes between pre- and post-operation ( P<0.05). The muscle strength was grade V. The TUG test ranged from 7.8 to 15.34 seconds (mean,10.79 seconds). X-ray films showed the prosthesis was not loose or displaced.

Conclusion

When RA patients receive 4JA, adequate preoperative evaluation, rational selection of the timing and sequence of surgery, and maximal restoration of lower limb alignment can achieve good mid-term effectiveness.

Does robotic technology successfully restore the joint line after total knee arthroplasty? A retrospective analysis

Background

Our study aims to determine the effectiveness of robotic technology for total knee arthroplasty in the successful restoration of the joint line of the knee with respect to that of a normal human anatomical knee. The restoration of the joint line is an important technical goal on which the postoperative outcomes and the success of the surgery depend.

Methods

Sixty-four postoperative plain anteroposterior radiographs of 60 patients, who received total knee arthroplasty by using the robotic technology were analyzed and compared with 66 similar radiographs of 60 patients who received the conventional method. The distances of the lateral epicondyle to the joint line (LEJL) and proximal tibiofibular joint to the joint line (PTFJJL) were calculated and analyzed.

Results

We found that the mean value of LEJL minus PTFJJL in the robotic group was 0.334 ± 0.115 (mean ± SD), while in the conventional group, it was 2.304 ± 0.308. The difference between the two groups was statistically significant. The mean ratio (LEJL:PTFJJL) in the robotic group was also equal to 1.017 ± 0.042.

Conclusion

From these findings it could be concluded that the robotic technology significantly increases the accuracy of the total knee arthroplasty and, compared to the conventional method, achieves an almost anatomical position of the joint line.

Doctor when can I drive? Braking response after knee arthroplasty: A systematic review & meta-analysis of brake reaction time

BACKGROUND

There is limited evidence available on return to driving for patients undergoing knee arthroplasty (KA). Primarily, surgeons have used brake reaction time as a surrogate measure of safe return to driving. The purpose of this study was to review existing literature and provide guidance on the recovery of braking performance following knee arthroplasty.

METHODS

A literature search was performed for prospective studies on driving after KA. Two reviewers screened citations for inclusion, assessed methodological quality, and extracted data. Values for total brake reaction-time (TBRT), movement-time (MT), reaction-time (RT), and braking-force (BF) were included for meta-analysis.

RESULTS

Twelve studies with 368 subjects were identified. TBRT, RT, MT, and BF relative to preoperative baseline were assessed. Meta-analysis of TBRT showed a significant improvement from preoperative baseline at 3 months & 1 year (p = 0.003 & p = 0.0001). MT showed a significant increase at 2 and 4 weeks (p = 0.00001 & p = 0.03) before returning to no being significantly different at 6 weeks and beyond. In contrast RTs were noted to improve significantly 2 weeks (p = 0.006), 4 weeks (p = 0.03), and 1 year (p = 0.0002).

CONCLUSION

Meta-analysis showed no significant difference in TBRT up until 3 months. RT increased significantly post-operatively suggesting it is not a reliable indicator. MT in contrast was significantly decreased post KA and may represent a more reliable measure of braking performance post KA. Surgeons should consider these recommendations and other patient factors that determine fitness to drive prior to advising their patients on a safe to return to driving.

Influence of Variation in Sagittal Placement of the Femoral Component after Cruciate-Retaining Total Knee Arthroplasty

Prosthetic alignment is an important factor for long-term survival in cruciate-retaining (CR) total knee arthroplasty (TKA). The purpose of this study is to investigate the influence of sagittal placement of the femoral component on tibiofemoral (TF) kinematics and kinetics in CR-TKA. Five sagittal placements of femoral component models with -3, 0, 3, 5, and 7 degrees of flexion are developed. The TF joint kinematics, quadriceps force, patellofemoral contact force, and posterior cruciate ligament force are evaluated using the models under deep knee-bend loading. The kinematics of posterior TF translation is found to occur with the increase in femoral-component flexion. The quadriceps force and patellofemoral contact force decrease with the femoral-component flexion increase. In addition, extension of the femoral component increases with the increase in posterior cruciate ligament force. The flexed femoral component in CR-TKA provides a positive biomechanical effect compared with a neutral position. Slight flexion could be an effective alternative technique to enable positive biomechanical effects with TKA prostheses.

Feasibility and efficacy of knee extension training using a single-joint hybrid assistive limb, versus conventional rehabilitation during the early postoperative period after total knee arthroplasty

Objectives: To evaluate the feasibility and efficacy of treatment for the recovery of knee joint function after total knee arthroplasty (TKA) using a robotic suit.

Patients and Methods: Knee joint extension exercise sessions were started with a robotic suit (single-joint hybrid assistive limb [HAL-SJ, Cyberdyne, Inc., Tsukuba, Japan]) in one group of patients after TKA. Patients who underwent standard rehabilitation were enrolled in the control group. To evaluate feasibility and safety, we assessed the adverse events, the number of training sessions, and training time. We compared the changes in knee joint pain and extension lag (°) between the groups.

Results: The average age was 71.3 ± 6.2 years in the HAL-SJ group and 74.9 ± 8.7 years in the control group. There were no severe adverse events. In the HAL-SJ group, training was performed 2.9 times, on average, and lasted 18.8 min. In the HAL-SJ group, there was a reduction in the visual analog scale (VAS) for pain after training, which was not significant. In the control group, the VAS score worsened after the sessions. The extension lag significantly improved in the HAL-SJ group after the 2nd and 3rd sessions, and this was more due to improvements in their active extension range of motion than their passive extension range of motion.

Conclusions: HAL-SJ-based training is safe and effective, and leads to instantaneous improvement of extension lag, without worsening knee joint pain. HAL-SJ-based knee extension training could represent a viable novel post-TKA rehabilitation modality.

Medial stabilizing technique preserves anatomical joint line and increases range of motion compared with the gap-balancing technique in navigated total knee arthroplasty

BACKGROUND

Medial compartment stability is important in total knee arthroplasty. The medial stabilizing technique (MST) has been proposed to achieve medial stability without excessive medial soft tissue release in total knee arthroplasty. Herein, we compare the MST and the gap-balancing technique (GBT) in navigated total knee arthroplasty.

METHODS

We retrospectively analyzed 70 patients with varus knee osteoarthritis who underwent primary total knee arthroplasty using the navigation system. They were divided into MST (n = 39) and GBT (n = 31) groups. We assessed intraoperative navigation data, radiographic data, and insert thickness. Preoperative and postoperative joint line changes were measured. We also assessed range of motion and clinical instability before and after total knee arthroplasty. These parameters were statistically compared between the groups.

RESULTS

Compared with the GBT group, medial extension gaps were significantly smaller in the MST group (P = 0.008). The gap difference between medial and lateral extension was significantly greater in the MST group (P = 0.018). Other navigation data showed no significant differences. Insert thickness and joint line changes were significantly lower in the MST group (P = 0.001, P = 0.018, respectively). Postoperative range of motion was significantly greater in the MST group (P = 0.032). There was no objective or subjective knee instability in either group.

CONCLUSION

The MST could avoid knee joint line changes and might increase postoperative range of motion. Although the MST permitted a discrepancy between medial and lateral gaps, no patients felt knee instability. The MST might improve the results of total knee arthroplasty.

Comparing cost and effectiveness of IVPCA morphine with perioperative multimodal analgesia of oral etoricoxib and oxycontin: A retrospective study

Introduction

Good pain control modality for post total knee replacement promotes patient's comfort and facilitates functional recovery, which may prevent post-operative complications; and shorten hospital stay. Therefore, manage pain efficiently and effectively have financial implications to the hospital. This retrospective study analyzed the clinical outcomes and costs of the intravenous (IV) patient-controlled analgesia (PCA) with a new perioperative multimodal analgesia (PMA) of using etoricoxib and oxycontin.

Methods

This retrospective study analyzed a total of 102 inpatients, 53 received both IVPCA and regular oral analgesics from September 2016 to February 2017, while 49 received preemptive oral etoricoxib before surgery and duly together with oxycontin and paracetamol after surgery from September 2017 to February 2018. Pain scores as the primary outcome were measured by Numeric Rating Scale (0–10) at rest (NRS-R) and on movement (NRS-M). They were analyzed by one-way analysis of covariance (ANCOVA). Other outcomes included side effects from analgesics, range of motion (ROM^o), patient satisfaction, length of hospital stay and costs of medications.

Results

Patients in PMA group achieved better outcomes than PCA group. NRS-M of PMA group shown lower mean pain score and (standard error) than PCA group (2.96 [0.31] vs 4.26 [0.29]; p = 0.003), side effects from analgesics (18% vs 45%), ROM≥ 90° (55.1% vs 30.2%), patient satisfaction (8.97 vs 7.5 out of 10; p = 0.005), and length of hospital stay (6 days vs 8 days; p < 0.001). Moreover, the medication cost of PMA was 59.9% lower than PCA regimen.

Conclusions

This PMA approach achieved better outcomes and saved hospital costs.

Assessing the Ankle Joint Line Level Before and After Total Ankle Arthroplasty With the "Joint Line Height Ratio"

BACKGROUND

Restoring the joint line is an important principle in total knee arthroplasty. However, the effect of joint line level on patient outcomes after total ankle arthroplasty (TAA) remains unclear, as there is no established method for measuring ankle joint level in TAA. The objective of this study was to develop a reliable radiographic ankle joint line measurement method and to compare ankle joint line level measured pre-TAA, post-TAA, and in nonarthritic ankles.

METHODS

A total of 112 radiographic sets were analyzed. Each set included weightbearing anteroposterior radiographs of the operative ankle taken preoperatively, 1-year postoperatively, and of the contralateral ankle. Measurements of vertical intermalleolar distance (VIMD) and vertical joint line distance (VJLD) at pre-TAA, post-TAA, and of the contralateral ankle were recorded by 2 authors on 2 separate occasions. The ratio of VJLD to VIMD was defined as the joint line height ratio (JLHR). Reliability of measurements and correlation between VIMD and VJLD were assessed. Pre-TAA, nonarthritic contralateral ankle, and post-TAA JLHR were compared and considered significantly different if P <.05.

RESULTS

The inter- and intrarater reliability of radiographic measurements was excellent (r > 0.9). There were strong positive correlations of VIMD and VJLD, r = 0.809 (pre-TAA)/0.756 (post-TAA), P < .001. Mean (SD) pre-TAA, nonarthritic contralateral ankle, and post-TAA JLHRs were 1.54 (0.31), 1.39 (0.26), and 1.62 (0.49), respectively. Pre- and post-TAA JLHRs were significantly higher compared to the nonarthritic contralateral ankle (P < .05). JHLR was not significantly different between pre- and post-TAA (P = .15).

CONCLUSION

The JLHR was reliable and could be a clinically applicable method for assessing ankle joint line level in patients undergoing TAA. End-stage ankle arthritis demonstrated elevated joint line level compared with nonarthritic ankles, and the joint line level post-TAA remained elevated compared with nonarthritic ankles. Further studies are needed to understand the effect of joint line elevation on clinical outcomes after TAA.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Variables Determining the Postoperative Knee Range of Motion Following Cruciate-substituting Total Knee Replacement: A Prospective Study

Introduction

Range of motion (ROM) is a major desirable outcome after total knee arthroplasty (TKA). The aim of our study is to analyze the variables determining postoperative knee ROM, following cruciate-substituting TKA of arthritic knees.

Methods

One-hundred fourteen patients out of a total of 158 patients were studied on the basis of the inclusion criteria. All patients underwent cruciate-substituting TKA in the period between September 2014 and September 2017. Variables such as age, sex, body mass index (BMI), preoperative ROM, mild-to-moderate knee deformity (in both the sagittal and coronal planes) and knee society score (KSS) were recorded for all the patients. The patients were evaluated at intervals and finally at the end of one-year post-surgery. The final ROM and KSS were noted. Data were analyzed in SPSS system using the Kruskal-Wallis test and Mann-Whitney U test.

Results

Patients with younger age (less than 60 years), more preoperative ROM, and less preoperative fixed flexion deformity (FFD) were found to have better postoperative ROM. The mean preoperative KSS was 42.14 ± 12.02, which improved to 90.86 ± 3.86 postoperatively. Other variables like gender, BMI, and preoperative coronal plane deformity of mild to moderate degree did not have a significant influence on postoperative ROM.

Conclusion

Postoperative expectations of ROM is an important factor for a successful outcome and is also related to patient satisfaction. Variables like younger age group (less than 60 years), better preoperative ROM and lower preoperative FFD are found to have a better postoperative ROM in patients undergoing cruciate-substituting TKA surgery.

Preoperative physiotherapy and short-term functional outcomes of primary total knee arthroplasty

INTRODUCTION

Physiotherapy is an important part of rehabilitation following arthroplasty, but the impact of preoperative physiotherapy on functional outcomes is still being studied. This randomised controlled trial evaluated the effect of preoperative physiotherapy on the short-term functional outcomes of primary total knee arthroplasty (TKA).

METHODS

50 patients with primary knee osteoarthritis who underwent unilateral primary TKA were randomised into two groups: the physiotherapy group (n = 24), whose patients performed physical exercises for six weeks immediately prior to surgery, and the nonphysiotherapy group (n = 26). All patients went through a similar physiotherapy regime in the postoperative rehabilitation period. Functional outcome assessment using the algofunctional Knee Injury and Osteoarthritis Outcome Score (KOOS) scale and range of motion (ROM) evaluation was performed preoperatively, and postoperatively at six weeks and three months.

RESULTS

Both groups showed a significant difference in all algofunctional KOOS subscales (p < 0.001). The mean score difference at six weeks and three months was not significant in the sports and recreational activities subscale for both groups (p > 0.05). Significant differences were observed in the time-versus-treatment analysis between groups for the symptoms (p = 0.003) and activities of daily living (p = 0.025) subscales. No significant difference in ROM was found when comparing preoperative measurements and those at three months following surgery, as well as in time-versus-treatment analysis (p = 0.928).

CONCLUSION

Six-week preoperative physiotherapy showed no significant impact on short-term functional outcomes (KOOS subscales) and ROM of the knee following primary TKA.

The effect of tourniquet and knee position during wound closure after total knee arthroplasty on early recovery of range of motion: a prospective, randomized study

INTRODUCTION

There is no consensus on the position of the knee joint while performing wound closure after total knee arthroplasty (TKA). Further, there are no studies focusing on the association between early functional outcomes and different wound closure strategies. Therefore, we investigated the effects of tourniquet and knee position during wound closure on early recovery of range of motion (ROM) after primary TKA. To our knowledge, this is the first study to evaluate the influence of both tourniquet and knee position during wound closure in primary TKA.

METHODS

One hundred-twenty eligible patients were consecutively enrolled in this study and randomly divided into four groups according to wound closure strategy. Wound closure was either performed with the knee in flexion at 90° or in full extension, with the combination of an inflated or deflated tourniquet. Visual analogue score (VAS), knee ROM, ROM recovery, knee society score (KSS), and wound complications were evaluated in the early postoperative period.

RESULTS

After the first postoperative week, ROM recovery in the group with knee in extension and inflated tourniquet was significantly lesser than the two groups with deflated tourniquets. Between the first and fourth postoperative weeks, ROM recovery in the group with knee inflection and deflated tourniquet was significantly higher than the two groups with knee in extension. After the first postoperative week, the visual analog score (VAS) for pain in the group with knee inflection and deflated tourniquet was significantly lesser than the two groups with inflated tourniquets. The differences in the outcomes between the four groups were not significant after the fourth postoperative week. The incidence of wound complications and KSS were not significantly different between the four groups.

CONCLUSION

Following TKA, wound closure with the knee in flexion and after deflating the tourniquet significantly decreased postoperative pain and promoted the recovery of ROM in the early postoperative period.

Knee-Extension Training with a Single-Joint Hybrid Assistive Limb during the Early Postoperative Period after Total Knee Arthroplasty in a Patient with Osteoarthritis

The knee range of motion is an important outcome of total knee arthroplasty (TKA). According to previous studies, the knee range of motion temporarily decreases for approximately 1 month after TKA due to postoperative pain and quadriceps dysfunction following surgical invasion into the knee extensor mechanism. We describe our experience with a knee-extension training program based on a single-joint hybrid assistive limb (HAL-SJ, Cyberdyne Inc., Tsukuba, Japan) during the acute recovery phase after TKA. HAL-SJ is a wearable robot suit that facilitates the voluntary control of knee joint motion. A 76-year-old man underwent HAL-SJ-based knee-extension training, which enabled him to perform knee function training during the acute phase after TKA without causing increased pain. Thus, he regained the ability to fully extend his knee postoperatively. HAL-SJ-based knee-extension training can be used as a novel post-TKA rehabilitation modality.

Recovery in knee range of motion reaches a plateau by 12 months after total knee arthroplasty

PURPOSE

The primary aim of this study was to identify the time point at which improvements in knee range of motion reach a plateau, if any. The secondary aim of this study was to investigate the correlation between the improvements in knee range of motion and patient-reported outcomes [Oxford knee score (OKS) and SF-36]. The hypothesis is that there is a time point at which the recovery in the knee range of motion after total knee arthroplasty (TKA) plateaus.

METHOD

A prospective study of 145 patients who underwent TKA was conducted. All TKAs were performed by the same surgeon. OKS and SF-36 scores were measured preoperatively and at 6, 12, and 24 months. Range of motion was measured preoperatively and at 1, 3, 6, 12, and 24 months postoperatively.

RESULTS

This study shows that for surgeon/therapist reported range of motion, a plateau in recovery was reached at 12 months after TKA. It was also found that range of extension is significantly correlated with OKS, whereas range of flexion was not significantly correlated with OKS.

CONCLUSIONS

Knowledge of when patients fully recover after TKA will allow appropriate counseling of patients during preoperative consultation. Also, this knowledge will enable surgeons/therapists to better monitor the rehabilitation progress of TKA patients, and make adjustments to the rehabilitation protocol. In addition, our study shows that objective surgeon-/therapist-measured outcome (range of motion) has a significant correlation with subjective patient-reported outcomes (OKS). Hence, both outcome measures should be employed in the postoperative monitoring of patient progress.

LEVEL OF EVIDENCE

Prospective case series, Level IV.

No statistically significant kinematic difference found between a cruciate-retaining and posterior-stabilised Triathlon knee arthroplasty

The aim of this study was to compare the maximum laxity conferred by the cruciate-retaining (CR) and posterior-stabilised (PS) Triathlon single-radius total knee arthroplasty (TKA) for anterior drawer, varus–valgus opening and rotation in eight cadaver knees through a defined arc of flexion (0º to 110º). The null hypothesis was that the limits of laxity of CR- and PS-TKAs are not significantly different.

The investigation was undertaken in eight loaded cadaver knees undergoing subjective stress testing using a measurement rig. Firstly the native knee was tested prior to preparation for CR-TKA and subsequently for PS-TKA implantation. Surgical navigation was used to track maximal displacements/rotations at 0º, 30º, 60º, 90º and 110° of flexion. Mixed-effects modelling was used to define the behaviour of the TKAs.

The laxity measured for the CR- and PS-TKAs revealed no statistically significant differences over the studied flexion arc for the two versions of TKA. Compared with the native knee both TKAs exhibited slightly increased anterior drawer and decreased varus-valgus and internal-external roational laxities. We believe further study is required to define the clinical states for which the additional constraint offered by a PS-TKA implant may be beneficial.

Cite this article: Bone Joint J 2015; 97-B:642–8.

Does joint line elevation after revision knee arthroplasty affect tibio-femoral kinematics, contact pressure or collateral ligament lengths? An in vitro analysis

INTRODUCTION

Correct restoration of the joint line is generally considered as crucial when performing total knee arthroplasty (TKA). During revision knee arthroplasty however, elevation of the joint line occurs frequently. The general belief is that this negatively affects the clinical outcome, but the reasons are still not well understood.

MATERIAL AND METHODS

In this cadaveric in vitro study the biomechanical consequences of joint line elevation were investigated using a previously validated cadaver model simulating active deep knee squats and passive flexion-extension cycles. Knee specimens were sequentially tested after total knee arthroplasty with joint line restoration and after 4 mm joint line elevation.

RESULTS

The tibia rotated internally with increasing knee flexion during both passive and squatting motion (range: 17° and 7° respectively). Joint line elevation of 4 mm did not make a statistically significant difference. During passive motion, the tibia tended to become slightly more adducted with increasing knee flexion (range: 2°), while it went into slighlty less adduction during squatting (range: -2°). Neither of both trends was influenced by joint line elevation. Also anteroposterior translation of the femoral condyle centres was not affected by joint line elevation, although there was a tendency for a small posterior shift (of about 3 mm) during squatting after joint line elevation. In terms of kinetics, ligaments lengths and length changes, tibiofemoral contact pressures and quadriceps forces all showed the same patterns before and joint line elevation. No statistically significant changes could be detected.

CONCLUSIONS

Our study suggests that joint line elevation by 4 mm in revision total knee arthroplasty does not cause significant kinematic and kinetic differences during passive flexion/extension movement and squatting in the tibio-femoral joint, nor does it affect the elongation patterns of collateral ligaments. Therefore, clinical problems after joint line elevation are probably situated in the patello-femoral joint or caused by joint line elevation of more than 4 mm.

Are joint line changes after primary navigated total knee arthroplasty predictable?

BACKGROUND

Navigation systems have been successful in reducing the outlier of leg alignment after total knee arthroplasty (TKA). Less is known about the restoration of the anatomical joint line with computer-assisted knee replacement. The aim of this study was to determine whether joint line changes <3 or ≥3 mm are predictable with several pre- and intraoperative parameters.

METHODS

The study included a total of 180 cases of primary computer-assisted TKA performed using the gap-balancing/tibia-first technique. The final shift of the joint line was calculated using computer verification of proximal tibial and distal femoral cuts. In consideration of the clinical relevance of a 3-mm joint line shift, patients were stratified into two groups: Group I, with joint line change <3 mm, and Group II, with joint line change ≥3 mm. Between groups, variables such as demographics, Kellgren & Lawrence degree of osteoarthritis, preoperative flexion contracture, pre-/intraoperative mechanical leg alignment, flexion/extension gaps, and implant design/sizes were compared statistically.

RESULTS

The absolute joint line shift averaged 1.6 ± 1.3 mm (range 0-6 mm). A joint line shift ≥3 mm was observed in 28 cases (15 %). A statistically significant difference between groups was not identified for any of the parameters. Shift of the joint line did not correlate with the analyzed variables.

CONCLUSIONS

Joint line was adequately restored when computer navigation was carefully applied as a measuring tool for primary TKA. Knee joint deformity, leg alignment, gap balance, and implant type did not aid in predicting the joint line shift.

Short-term functional versus patient-reported outcome of the bicruciate stabilized total knee arthroplasty: prospective consecutive case series

Background

The main goals of the standard treatment for advanced symptomatic knee osteoarthritis, total knee arthroplasty (TKA), are pain reduction and restoration of knee motion.

The aim of this study was to analyse the outcome of the patient-based Knee Injury and Osteoarthritis Outcome Score (KOOS), and the surgeon-based Knee Society Score (KSS) and its Knee Score (KS) and Knee Functional Score (KFS) components after (TKA) using the Journey knee prosthesis, and to assess the correlation of these scores with range of motion (ROM).

Methods

In a prospective case series study between August 1^st 2008 and May 31^st 2011, 99 patients, all operated by a single surgeon, received Journey bicruciate stabilized total knee prostheses. The female/male ratio was 53/34, the mean patient age at surgery was 68 years (range 41–83 years), and the left/right knee ratio was 55/44. The KOOS, range of motion, and KS and KFS were obtained preoperatively and at 1-year follow-up. The pre- and postoperative levels of the outcome measures were compared using the Wilcoxon signed-rank test. Correlation between ROM and patient outcomes was analysed with the Spearman coefficient.

Results

All KOOS subscores improved significantly. Ninety percent of patients improved by at least the minimum clinically relevant difference of 10 points in stiffness and other symptoms, 94.5% in pain, 94.5% in activities of daily living, 84.9% in sports and recreation, and 90% in knee-related quality of life. The mean passive and active ROM improved from 122.4° (range 90-145°) and 120.4° (range 80-145°) preoperatively to 129.4° (range 90-145°) and 127.1° (range 100-145°) postoperatively. The highest correlation coefficients for ROM and KOOS were observed for the activity and pain subscores. Very low or no correlation was seen for the sport subscore.

There was a significant and clinically relevant improvement of KSS (preop/postop 112.2/174.5 points), and its KS (preop/postop 45.6/86.8 points) and KFS (preop/postop 66.6/87.8 points) components.

Conclusions

The Journey bicruciate stabilized knee prosthesis showed good 1-year postoperative results in terms of both functional and patient-based outcome. However, higher knee ROM correlates only moderately with patient-based outcome, implying that functionality afforded by the Journey bicruciate TKA is not equivalent to patient satisfaction.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-435) contains supplementary material, which is available to authorized users.

Bicruciate substituting design does not improve maximal flexion in total knee arthroplasty: a randomized controlled trial

BACKGROUND

An important factor in the functional results after total knee arthroplasty is the achieved maximal flexion. The main purpose of this study was to compare the maximal knee flexion one year after surgery in patients who received either the bicruciate substituting knee system or the conventional posterior stabilized system.

METHODS

In a prospective randomized controlled trial, 124 patients presenting with osteoarthritis received the bicruciate substituting or the conventional posterior stabilized prosthesis. The primary outcome was the maximum flexion angle at one year postoperatively on a lateral radiograph made with the supine patient using manual force to bend the knee. Secondary outcomes were active flexion (lying and standing), the Knee Society Score, the Patella Scoring System score, the University of California Los Angeles score, the number and type of adverse device effects, and visual analog scale satisfaction up to two years postoperatively. The outcome measures of both groups were compared using one-sided t tests and non-parametric alternatives, with a significance level of p < 0.05.

RESULTS

No significant differences between the two groups were observed in maximal flexion on radiographs and in active flexion at baseline. The median maximal flexion on radiographs was 127° (range, 83° to 150°) for the bicruciate substituting group and 125° (range, 74° to 145°) for the conventional posterior stabilized group. The two groups showed comparable two-year results with respect to the Knee Society Score, the Patella Scoring System, the University of California Los Angeles score, and visual analog scale satisfaction. In the bicruciate substituting group, forty-one adverse device effects in twenty-six patients were reported, including three total system revisions and fourteen manipulations under anesthesia, compared with the conventional posterior stabilized group, in which sixteen adverse device effects were observed in thirteen patients, including six manipulations under anesthesia (p = 0.012).

CONCLUSIONS

Patients who receive a bicruciate substituting system compared with those who receive a conventional posterior stabilized system have comparable knee flexion characteristics and clinical and functional outcomes but more complications by two years after total knee arthroplasty.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Does flexion of the femoral implant in total knee arthroplasty increase knee flexion: a randomised controlled trial

INTRODUCTION

Prosthetic and operative modifications in total knee arthroplasty (TKA) have been proposed to maximise post-operative knee flexion as it is essential in routine functional activities.

METHODS

We performed a double blind randomised controlled trial to compare clinical outcomes of primary cruciate-retaining TKA for osteoarthritis with the femoral component implanted in either 4° flexion in the sagittal plane (F) or in a neutral position (C). The primary outcome of knee flexion and secondary outcomes knee extension, quadriceps strength, WOMAC, SF-12v2, timed stand test, stair climb test and satisfaction were assessed at 1 year. Knee flexion and extension were also assessed intra-operatively. Implant flexion was measured from true lateral radiographs.

RESULTS

Thirty-nine participants (40 knees) were recruited, 20 knees per group. Three subjects from the control group and two from the flexed group were lost to 1 year follow-up but numbers were sufficient to satisfy the sample size calculation. Significant differences were found between the groups in knee flexion (F: 113.6±8.8° pre-operative, 122.4±6.0° intra-operative, 110.2±7.5° 1 year, C: 117.4±11.7°, 117.4±7.6°, 103.5±10.7°. p=0.031) and mental component score of the SF12-v2 (F 53.3±13.2, C 61.1±7.3, p=0.009) but there were no significant differences in other outcomes and patients were equally satisfied.

CONCLUSION

Flexing the femoral implant in this cruciate retaining TKA system provided a significant difference in knee flexion compared to a neutral position. The improvement appears to occur predominantly at surgery and was not associated with a clinical or functional benefit at 1 year. (ACTRN12606000325505).

LEVEL OF EVIDENCE

Level 1; randomised controlled trial.

Patellar tilt and thickness do not influence postoperative flexion in a high-flex design total knee arthroplasty

PURPOSE

The purpose of this short-term study was to determine whether patellar thickness and tilt influence the postoperative flexion in a high-flex design total knee arthroplasty (TKA).

METHODS

Between 2007 and 2009, 106 patients underwent surgery for TKA using rotating platform flex prosthesis (DePuy, Warsaw, Ind). All of them were suffering from end-stage osteoarthritis. All patients were evaluated preoperatively and at 12 months of follow-up. Maximum active, non-weight-bearing flexion was the primary outcome parameter. Standard standing antero-posterior and lateral weight-bearing radiographs were made. The patellofemoral joints were evaluated in skyline views taken with the knees at approximately 60° of flexion. Patellar thickness, patellar tilt, Caton-Deschamps indices and lower limb alignment were measured.

RESULTS

The mean flexion observed before surgery was 125° ± 15° and after 1 year was 128° ± 13°. The mean patellar thickness preoperatively was 24.5 ± 2.9 and 25.8 ± 3.2 mm at 12 months after surgery. The mean patellar tilt before the procedure was 2.9° ± 4.1° and after 12 months of follow-up was -0.8° ± 5.0°. The mean preoperative hip-knee-ankle was 2.6° ± 6.2°. No significant correlation was found between postoperative patellar tilt and thickness and postoperative flexion (n.s.).

CONCLUSIONS

Patellar tilt and thickness after TKA are factors that depend on the surgery. The resection of the patella can influence both patellar thickness and patellar tilt. By developing adequate surgical instruments, it would be possible to avoid the occurrence of an exaggerated patellar tilt or a major difference in patellar thickness. However, these two factors did not seem to influence the postoperative flexion in a high-flex design TKA, which can be seen as one of the most important outcome factors after TKA.

Single-radius, multidirectional total knee replacement

PURPOSE

The present study was designed to evaluate the mid-term (5- to 8-year) survival rate of a new total knee replacement (TKR) with a single-radius femoral component and a multidirectional, highly congruent tibial component, in comparison with an historical group (TKR with multi-radius design and fixed bearing).

METHODS

Four hundred and thirty patients were included, of which 369 patients (86 %) completed the 5-year follow-up with Knee Society Score evaluation and radiograph examination (study group = 387, control group = 83).

RESULTS

There was a significant improvement for all analysed items between pre-operative status and late follow-up. Mean knee score was 93 ± 9 points in the study group and 88 ± 16 points in the control group (p < 0.001). Mean flexion angle was not different (118 ± 11 vs. 114 ± 13 degrees). Mean functional score was 87 ± 16 points in the study group and 71 ± 24 points in the control group (p < 0.001). Survival rate at 5-year follow-up was 98.8 % (vs. 98.0 %) for mechanical revisions only, and 96.4 % (vs. 98.1 %) for all revisions.

CONCLUSIONS

The new TKR allowed obtaining significantly better results than the fixed-bearing TKR. These results are in line with the best series published in the current literature, but there was no evidence of any superiority of this TKR against already published standards.

Joint line changes after primary total knee arthroplasty: navigated versus non-navigated

PURPOSE

Navigation has been introduced to achieve more accurate positioning of the implants after TKA. The scientific attention was mainly paid on limb alignment rather than restoration of the natural joint line. The aim of our study was to compare the accuracy of the joint line restoration in primary TKA with and without navigation. We hypothesized that joint line reconstruction in navigated TKA is more accurate.

METHODS

A total of 493 primary TKAs operated in a single medical centre were consecutively selected and divided into two groups. 206 cases were performed computer assisted (BrainLab CI-System), whereas 287 knees were implanted conventionally. For both groups, the joint line position of the knee was determined on standardized calibrated standing pre- and postoperative digital radiographs in ap view by a modified method of Kawamura et al. A joint line shift of more than 8 mm was defined as outlier.

RESULTS

In the conventional group, the joint line shift averaged 0.7 mm (±4.4 mm), whereas the findings in the computer-assisted cases were in average 0.6 mm (±4.5 mm). The joint line was located above 8 mm in 6 % of non-navigated versus 6.8 % of navigated primary TKAs. There were no statistically significant differences of joint line shift between the different component types. A statistically significant relation was not found between joint line shift and leg alignment changes.

CONCLUSIONS

Conventional surgical technique allows a precise joint line reconstruction in primary TKA. Navigation did not improve the joint line reconstruction.

LEVEL OF EVIDENCE

Diagnostic study, Level III.

Use of static or articulating spacers for infection following total knee arthroplasty: a systematic literature review

BACKGROUND

The so-called gold standard for treatment of periprosthetic joint infection following total knee arthroplasty is two-stage reimplantation. However, it is unclear whether use of static or articulating antibiotic-impregnated spacers during the interim period between these two stages is superior. The purpose of this study was to compare the outcomes of static and articulating spacers in the treatment of infection following total knee arthroplasty.

METHODS

A systematic review of the peer-reviewed literature indexed by MEDLINE and Embase was performed to identify studies reporting the outcomes of antibiotic spacers in the treatment of infection following total knee arthroplasty. Seven Level-III comparative studies and thirty-two Level-IV case series remained following the screening process. The data in these studies were extracted and aggregated to compare the reinfection rate, range of knee motion, functional scores, and complication rates between static and articulating spacers.

RESULTS

The two types of spacers demonstrated similar reinfection rates (7% for articulating and 12% for static, p = 0.2). However, the articulating spacers resulted in significantly greater range of knee motion after reimplantation (101° for articulating and 91° for static, p = 0.0002). Despite this difference in ultimate knee motion, functional scores in the treatment groups were similar. Rates of wound-related and spacer-related complications were similarly low with both types of spacers.

CONCLUSIONS

Our review failed to identify a significant difference in the ability of static or articulating spacers to eradicate periprosthetic infection following total knee arthroplasty. Compared with static spacers, articulating spacers provided improved knee motion following reimplantation, although functional scores were similar in the two treatment groups. We encourage arthroplasty surgeons to consider both static and articulating spacers in the treatment of infection following total knee arthroplasty and to tailor treatment on the basis of patient-related factors.

Perioperative administration of selective cyclooxygenase-2 inhibitors for postoperative pain management in patients after total knee arthroplasty

Total knee arthroplasty (TKA) is associated with considerable postoperative pain. The relative analgesic efficacy and adverse effect profile of perioperative use of selective cyclooxygenase-2 (COX-2) inhibitors for patients undergoing TKA are unclear. This is a systematic review and meta-analysis of all randomized controlled trials evaluating perioperative administration of COX-2 inhibitors for TKA. Eight studies that had enrolled a total of 571 patients were identified. There was a statistical significance in postoperative pain scores (0-24 hours: P = .0007, 24-48 hours: P = .01, 48-72 hours: P < .0001), opioid consumption (P = .006), active range of motion (P = .002), itching (P = .005), and postoperative nausea/vomiting (P = .003) between groups. There was no difference in blood loss during the first 24 hours after operation between groups. The efficacy of perioperative administration of selective COX-2 inhibitors to reduce postoperative pain and opioid consumption after TKA is validated. Furthermore, it has important outcome benefits after TKA.

Does a mobile-bearing, high-flexion design increase knee flexion after total knee replacement?

This prospective randomised controlled double-blind trial compared two types of PFC Sigma total knee replacement (TKR), differing in three design features aimed at improving flexion. The outcome of a standard fixed-bearing posterior cruciate ligament-preserving design (FB-S) was compared with that of a high-flexion rotating-platform posterior-stabilised design (RP-F) at one year after TKR. The study group of 77 patients with osteoarthritis of the knee comprised 37 men and 40 women, with a mean age of 69 years (44.9 to 84.9). The patients were randomly allocated either to the FB-S or the RP-F group and assessed pre-operatively and at one year post-operatively. The mean post-operative non-weight-bearing flexion was 107° (95% confidence interval (CI) 104° to 110°)) for the FB-S group and 113° (95% CI 109° to 117°) for the RP-F group, and this difference was statistically significant (p = 0.032). However, weight-bearing range of movement during both level walking and ascending a slope as measured during flexible electrogoniometry was a mean of 4° lower in the RP-F group than in the FB-S group, with 58° (95% CI 56° to 60°) versus 54° (95% CI 51° to 57°) for level walking (p = 0.019) and 56° (95% CI 54° to 58°) versus 52° (95% CI 48° to 56°) for ascending a slope (p = 0.044). Further, the mean post-operative pain score of the Western Ontario and McMaster Universities Osteoarthritis Index was significantly higher in the RP-F group (2.5 (95% CI 1.5 to 3.5) versus 4.2 (95% CI 2.9 to 5.5), p = 0.043). Although the RP-F group achieved higher non-weight-bearing knee flexion, patients in this group did not use this during activities of daily living and reported more pain one year after surgery.

Gender-specific high-flexion knee prosthesis in Indian women: a prospective randomised study

PURPOSE

To compare outcomes in Indian women who underwent total knee arthroplasty (TKA) using the standard Legacy Posterior Stabilised (LPS) versus the gender-specific LPS high-flexion knee prosthesis.

METHODS

100 women (200 knees) aged 60 to 80 years with an arc of flexion of ≥90º underwent simultaneous sequential TKA for primary osteoarthritis of both knees. They were randomised to receive the standard NexGen LPS prosthesis (n=50) or the gender-specific NexGen LPS High-Flex prosthesis (n=50). Both knees in each patient received the same prosthesis. The resected bone from the posterior femoral condyle was 2 mm greater when the gender-specific prosthesis was used. Patients were followed up at 3, 6, 12, and 24 months. Range of motion, Knee Society score, and Hospital for Special Surgery score were evaluated pre- and post-operatively by a single assessor.

RESULTS

The mean follow-up duration was 2.1 (range, 1.6-2.5) years. Respectively for the standard and gender-specific groups, the mean range of motion was 111º and 112º preoperatively and 120º and 123º at the latest follow-up. The gender-specific group gained approximately 3º more in range of motion (p=0.007). The Knee Society score and the Hospital for Special Surgery score between groups were not significantly different pre- and post-operatively.

CONCLUSION

The perceived advantage of a gender-specific prosthesis over a standard prosthesis did not translate into better clinical and functional outcome scores.

Is discharge knee range of motion a useful and relevant clinical indicator after total knee replacement? Part 2

OBJECTIVE

Knee range of motion (ROM) at discharge from acute care is used as a clinical indicator following total knee replacement (TKR) surgery. This study aimed to assess the clinical relevance of this indicator by determining whether discharge knee ROM predicts longer-term knee ROM and patient-reported knee pain and function.

METHODS

A total of 176 TKR recipients were prospectively followed after discharge from acute care. Outcomes assessed included knee ROM and Oxford knee score post rehabilitation and 1 year post surgery. Discharge ROM and other patient factors were identified a priori as potential predictors in multiple linear regression modelling.

RESULTS

A total of 133 (76%) and 141 (80%) patients were available for follow-up post rehabilitation [mean postoperative week 8.1 (SD 2.7)] and at 1 year [mean postoperative month 12.1 (SD 1.4)], respectively. Greater discharge knee flexion was a significant (P < 0.001) predictor of greater post-rehabilitation flexion but not 1-year knee flexion (P < 0.083). Better discharge knee extension was a significant predictor of better post-rehabilitation (P = 0.001) and 1-year knee extension (P = 0.013). Preoperative Oxford score and post-rehabilitation knee flexion independently predicted post-rehabilitation Oxford score, and gender predicted 1-year Oxford score. Discharge ROM did not significantly predict Oxford score in either model.

CONCLUSION

The finding that early knee range predicts longer-term range provides clinical evidence favouring the relevance of discharge knee ROM as a clinical indicator. Although longer-term patient-reported knee pain and function were not directly associated with discharge knee ROM, they were associated with ROM when measured concurrently in the sub-acute phase. No causal effect has been demonstrated, but the findings suggest it may be important for physiotherapists to maximize range in the early and sub-acute periods.

Improvements in knee range and symptomatic and functional behavior after knee arthroplasty based on preoperative restriction in range

Recovery of knee range and Oxford Knee Score post knee arthroplasty based on preoperative knee range is described. A total of 191 patients recruited across 5 hospitals were assessed preoperatively, at 8 weeks postoperatively and 1 year. Preoperative knee range was categorized into "low" (≤ 109), "moderate" (> 109 to ≤ 120), and "high" (> 120°) flexion and "normal" (± -5) and "restricted" (> +5°) terminal extension. Recovery was analyzed using MIXED modeling procedures. The low-flexion group gained flexion across time. The moderate-flexion and high-flexion groups lost flexion initially then recovered, but 1-year flexion remained lower than preoperative values. The restricted terminal extension group gained extension across time. The normal terminal extension group lost extension initially then recovered to preoperative values at 1 year. Recovery in Oxford score was independent of preoperative knee range limitation. Improvement in knee range postoperatively, but not self-reported behavior, is highly dependent on the initial restriction in range.

Is discharge knee range of motion a useful and relevant clinical indicator after total knee replacement? Part 1

OBJECTIVES

Knee range of motion (ROM) at the point of discharge from acute care is used as a clinical indicator to benchmark performance between hospital services after total knee replacement (TKR). The utility of the current benchmark, including whether discharge ROM varies between hospitals, is unknown. This study aimed to determine whether the benchmark [≥80 degrees flexion and ≤5 degrees fixed flexion (extension)] is realistic and whether the service provider is a predictor of knee ROM.

METHODS

A prospective, observational cohort study was conducted involving 176 TKR patients from four hospitals. Knee ROM was photographically assessed preoperatively and at discharge. 'Hospital', typical patient demographic data and preoperative ROM were identified a priori as potential predictors of knee ROM.

RESULTS

Overall, 2% [95% CI (confidence interval) 1-6] of patients attained the ROM benchmark. Individual hospital attainment of the benchmark ranged 0-7% with a significant difference (P = 0.047) evident between the best performer and the remaining hospitals. The overall rates of attainment of the individual flexion (25%, 95% CI 19-32) and extension (15%, 95% CI 10-21) components were similarly low, although the scatter between hospitals was large [flexion (2-47%); extension (8-44%)]. Preoperative flexion and hospital were significant (P = 0.002) predictors of discharge flexion, explaining 21% of the variance. Similarly, hospital and preoperative extension together with gender were significant (P < 0.001) predictors of discharge extension, explaining 26% of the variance.

CONCLUSIONS

A small minority of patients attained the knee ROM benchmark, indicating the existing standard is unrealistic. Nevertheless, that 'hospital' is an important predictor confirms the potential of ROM for benchmarking purposes. Differences in physiotherapy practices may contribute to inter-hospital variation in discharge knee ROM together with other undefined factors. The causal relationships explaining the variation and the relationship between discharge ROM and longer-term outcome are avenues for future exploration which will help define the clinical relevance of the indicator.

Early clinical results of a high-flexion, posterior-stabilized, mobile-bearing total knee arthroplasty: a US investigational device exemption trial

Between May 2001 and June 2004, 388 total knee arthroplasty cases were enrolled in a prospective, randomized, multicenter investigational device exemption trial. Patients received either the investigational high-flexion mobile-bearing knee or a fixed-bearing control. At 2 to 4 years of follow-up, results in 293 patients with degenerative joint disease were compared using Knee Society Assessment and Function scores, radiographic results, complications analysis, and survival estimates. The mobile-bearing and fixed-bearing groups demonstrated similar, significant improvement over preoperative assessments in Knee Scores, maximum flexion, and range of motion. One mobile-bearing arthroplasty required revision. Radiographic results were unremarkable, and implant-related complications were rare in both groups. At this early follow-up, the investigational high-flexion mobile-bearing knee and its fixed-bearing counterpart demonstrated comparable, effective performance.

[Soft tissue balanced navigation of total knee arthroplasties]

OBJECTIVE

Implantation of a total knee arthroplasty with a correct mechanical axis, a rectangular joint gap and a reconstructed joint line by use of an imageless computer navigation device

INDICATIONS

Symptomatic gonarthrosis if non operative treatment or joint preserving operations remains ineffective

CONTRAINDICATIONS

Infections; soft tissue damage in the approach area; massive instability of the collateral ligaments

SURGICAL TECHNIQUE

Medial parapatellar approach to the knee joint; diminution of the patella; fixation of the reference arrays in tibia and femur; registration of leg axis, ligament balance and surface of the knee joint by use of the navigation system; tibial resection perpendicular to the mechanical axis; ligament balancing to achieve a rectangular extension gap; femoral implant planning to maintain the original joint line and reconstruct an equal joint gap in extension and flexion; femora resection perpendicular to the mechanical axis; reconstruction of the rectangular flexion gap by rotation of the femoral resection; two stage cementing technique for fixation of the original implants; check of the final mechanical axis and symmetry of the joint gap over the whole range of motion; wound closure.

POSTOPERATIVE MANAGEMENT

Physiotherapy; continuous passive motion treatment; mobilization with 20 kg weight bearing with 2 crutches for 2 weeks, thereafter with 2 crutches and incremental full weight bearing for 4 weeks.

RESULTS

The analysis of 582 consecutive navigated total knee arthroplasties showed one case of extension gap instability  > 3 mm (0.2%) and 8 patients with flexion gap instability  > 3 mm (1.4%). A too tight flexion gap was registered in 23 patients (4.4%), a too wide flexion gap in 13 cases (2.5%). The joint line was reconstructed with an average inaccuracy of 0 mm, in 17 patients the joint line was elevated  > 3 mm (2.9%).

A Comparison of the Clinical and Radiographic Results of Press Fit Condylar Rotating-Platform High-Flexion and Low Contact Stress Mobile Bearing Prosthesis in Total Knee Arthroplasty: Short term Results

Purpose

This study compared the results of rotating-platform high-flexion (RP-F) total knee arthroplasty with low contact stress (LCS) for clinical and radiographical assessment after a short-term period.

Materials and Methods

68 total knee arthroplasties using a RP-F and LCS system were analyzed retrospectively. Thirty-five of the 68 were osteoarthritic knees and were followed-up for more than 2 years. The clinical evaluation included range of motion (ROM), Knee Society Knee Score and Function Score (KSKS and KSFS), tailor position and kneeling. The radiographic evaluation included femorotibial angle, position of implants, radiolucent line and position of patella.

Results

The postoperative ROM, KSKS, and KSFS improved statistically in both implants. Comparing RP-F with LCS there were statistically no differences in ROM (p=0.863), KSKS (p=0.835), KSFS (p=0.535) and tailor position (p=0.489). There were no significant radiographic differences.

Conclusions

Total knee arthroplasty with RP-F and LCS showed similar clinical and radiographic results; it also showed excellent and predictable results at the short-term follow up. However, in RP-F there was 1 case of early osteolysis, 1 case of patella clunk syndrome and 1 case of painful patella crepitus; therefore, further case studies and follow-up are needed.

The EUROP total knee prosthesis: a ten-year follow-up study of a posterior cruciate-retaining design

INTRODUCTION

The success of total knee arthroplasty is measured by pain relief, functional recovery, and implant survival duration. The aim of the present study was to evaluate the long-term clinical, functional and radiological results of the posterior cruciate ligament (PCL)-retaining fixed bearing EUROP implant.

HYPOTHESIS

The long-term results of EUROP implants are similar to those reported with comparable prostheses.

PATIENTS AND METHODS

We performed a prospective, monocentric study of a series of 121 cemented EUROP total knee arthroplasties, implanted between 1994 and 1996 in 117 patients mean age 73. A clinical and radiological evaluation was performed at 10 years of follow-up according to the International Knee Society (IKS) score. Twenty-three patients died, 14 were lost to follow-up, 43 underwent clinical and radiological evaluation and 37 were questioned by telephone.

RESULTS

The preoperative IKS knee score was 31 points (0-60) and increased to 88 points (30-98) at final follow-up, IKS function increased from 40 (0-90) to 80 points (25-100). Radiolucencies were observed in 56% of the condyles and 60% of tibial plates. Ninety-three percent of these radiolucent lines were less than 1mm wide. Three patients underwent revision TKA at 32 months, eight and 11 years respectively. Global implant survival was 99% at five years, 97.8% at 10 years and 95.8% at 12 years.

DISCUSSION

The clinical and radiological results of the cruciate-retaining fixed bearing EUROP total knee arthroplasties, with three cases of revision arthroplasty at 12 years of follow-up are satisfactory and comparable to similar implants.

Validity and reliability of using photography for measuring knee range of motion: a methodological study

Background

The clinimetric properties of knee goniometry are essential to appreciate in light of its extensive use in the orthopaedic and rehabilitative communities. Intra-observer reliability is thought to be satisfactory, but the validity and inter-rater reliability of knee goniometry often demonstrate unacceptable levels of variation. This study tests the validity and reliability of measuring knee range of motion using goniometry and photographic records.

Methods

Design: Methodology study assessing the validity and reliability of one method ('Marker Method') which uses a skin marker over the greater trochanter and another method ('Line of Femur Method') which requires estimation of the line of femur. Setting: Radiology and orthopaedic departments of two teaching hospitals. Participants: 31 volunteers (13 arthritic and 18 healthy subjects). Knee range of motion was measured radiographically and photographically using a goniometer. Three assessors were assessed for reliability and validity. Main outcomes: Agreement between methods and within raters was assessed using concordance correlation coefficient (CCCs). Agreement between raters was assessed using intra-class correlation coefficients (ICCs). 95% limits of agreement for the mean difference for all paired comparisons were computed.

Results

Validity (referenced to radiographs): Each method for all 3 raters yielded very high CCCs for flexion (0.975 to 0.988), and moderate to substantial CCCs for extension angles (0.478 to 0.678). The mean differences and 95% limits of agreement were narrower for flexion than they were for extension. Intra-rater reliability: For flexion and extension, very high CCCs were attained for all 3 raters for both methods with slightly greater CCCs seen for flexion (CCCs varied from 0.981 to 0.998). Inter-rater reliability: For both methods, very high ICCs (min to max: 0.891 to 0.995) were obtained for flexion and extension. Slightly higher coefficients were obtained for flexion compared to extension, and with the Marker compared to the Line of Femur Method. For intra- and inter-rater reliability, the mean differences (within 2 degrees) and 95% limits of agreement (within 5 degrees) were generally clinically acceptable for both methods.

Conclusion

Photography potentially offers a superior method of measurement over standard goniometry as visualising the centre of the knee is simplified in a two-dimensional plane and the permanent record provides greater assessor transparency as well as opportunity to confer. The Marker and Line of Femur Methods have moderate to substantial validity, but the inter- and intra-rater repeatability for trained observers are excellent with both methods yielding small mean differences with narrow limits of agreement. The Line of Femur Method offers the added advantage that it does not rely on inter-clinician consistency in identifying the greater trochanter.

Active, passive and proprioceptive neuromuscular facilitation stretching are comparable in improving the knee flexion range in people with total knee replacement: a randomized controlled trial

Objective: To compare the immediate and medium-term effects of three stretching methods on the knee flexion range in people with a total knee replacement.

Design: Randomized clinical trial.

Setting: Rehabilitation hospital.

Subjects: 117 patients were recruited and 100 (mean age: 68.43 ± 7.95 years) of them completed the study.

Interventions: Patients receiving total knee replacement due to knee osteoarthritis were randomly assigned into 3 groups of: active stretching (group 1, n =32), passive stretching (group 2, n =35) and proprioceptive neuromuscular facilitation stretching (group 3, n =33).

Main measures: The immediate change in both active and passive knee flexion range after the first treatment session and the pattern of change in these ranges throughout the 2-week study period were compared among the three groups.

Results: All groups demonstrated significant improvement in knee ranges with time. The active range of group 1 improved by 19.9°, group 2 by 25.3° and group 3 by 22.5° throughout the 2-week period, whereas the improvements in the passive range were 18.8°, 24.5° and 22.7°, respectively. For between-group comparisons, no significant difference was found in both active (P = 0.647) and passive (P = 0.501) knee range immediately after stretching. For the changes at 2 weeks, there was also no significant difference among the groups in both active (P = 0.716) and passive (P = 0.959) knee ranges.

Conclusion: This study revealed that all three modes of stretching were associated with an increase in the knee flexion range of patients after total knee replacement, with no statistically significant differences between the changes seen.

Can an anterior quadriceps release improve range of motion in the stiff arthritic knee?

We hypothesize that tethering adhesions of the quadriceps muscle are the major pathological structures responsible for a limited range of motion in the stiff arthritic knee. Forty-two modified quadriceps muscle releases were performed on 24 patients with advanced osteoarthritis scheduled for total knee arthroplasty. The ranges of motion were documented intraoperatively both before and immediately after the release. Passive flexion improved significantly in all patients (mean, 32.4 degrees of improvement, P < .001) following a modified quadriceps release, despite any presence of osteophytes or severe deformities. These results strongly implicate adhesions of the quadriceps muscle to the underlying femur, which prevent the distal excursion of the quadriceps tendon, as the restrictive pathology preventing deep flexion in patients with osteoarthritis.

Overhang of the femoral component in total knee arthroplasty: risk factors and clinical consequences

BACKGROUND

Recently, much attention has been directed to femoral component overhang in total knee arthroplasty. The purposes of this study were to describe the prevalence of femoral component overhang among men and women after total knee arthroplasty, to identify risk factors for overhang, and to determine whether overhang was associated with postoperative knee pain or decreased range of motion.

METHODS

Femoral component overhang was measured intraoperatively during 437 implantations of the same type of total knee arthroplasty prosthesis. The overhang of metal beyond the bone cut edge was measured in millimeters at the midpoint of ten zones after permanent fixation of the implant. Factors predictive of overhanging fit were identified, and the effect of overhang on postoperative pain and flexion was examined.

RESULTS

Overhang of >or=3 mm occurred in at least one zone among 40% (seventy-one) of 176 knees in men and 68% (177) of 261 knees in women, most frequently in lateral zones 2 (anterior-distal) and 3 (distal). Female sex, shorter height, and larger femoral component size were highly predictive of greater overhang in multivariate models. Femoral component overhang of >or=3 mm in at least one zone was associated with an almost twofold increased risk of knee pain more severe than occasional or mild at two years after surgery (odds ratio, 1.9; 95% confidence interval, 1.1 to 3.3).

CONCLUSIONS

In this series, overhang of the femoral component was highly prevalent, occurring more often and with greater severity in women, and the prevalence and magnitude of overhang increased with larger femoral component sizes among both sexes. Femoral component overhang of >or=3 mm approximately doubles the odds of clinically important knee pain two years after total knee arthroplasty.

Joint line elevation in revision TKA leads to increased patellofemoral contact forces

One difficulty in revision total knee arthroplasty (TKA) is the management of distal femoral bone defects in which a joint line elevation (JLE) is likely to occur. Although JLE has been associated with inferior clinical results, the effect that an elevated joint line has on knee contact forces has not been investigated. To understand the clinical observations and elaborate the potential risk associated with a JLE, we performed a virtual TKA on the musculoskeletal models of four subjects. Tibio- and patellofemoral joint contact forces (JCF) were calculated for walking and stair climbing, varying the location of the joint line. An elevation of the joint line primarily affected the patellofemoral joint with JCF increases of as much as 60% of the patient's body weight (BW) at 10-mm JLE and 90% BW at 15-mm JLE, while the largest increase in tibiofemoral JCF was only 14% BW. This data demonstrates the importance of restoring the joint line, as it plays a critical role for the magnitudes of the JCFs, particularly for the patellofemoral joint. JLE caused by managing distal femoral defects with downsizing and proximalizing the femoral component could increase the patellofemoral contact forces, and may be a contributing factor to postoperative complications such as pain, polyethylene wear, and limited function.

Perioperative oral pregabalin reduces chronic pain after total knee arthroplasty: a prospective, randomized, controlled trial

BACKGROUND

Despite the enormous success of total knee arthroplasty (TKA), chronic neuropathic pain can develop postoperatively and is both distressing and difficult to treat once established. We hypothesized that perioperative treatment with pregabalin, a chronic pain medication, would reduce the incidence of postsurgical neuropathic pain.

METHODS

We performed a randomized, placebo-controlled, double-blind trial of pregabalin (300 mg) administered before TKA and for 14 days after TKA (150-50 mg twice daily). Patients were screened for the presence of neuropathic pain at 3 and 6 mo postoperatively using the Leeds Assessment of Neuropathic Symptoms and Signs scale. Secondary outcomes included postsurgical recovery and rehabilitation measures, including knee range of motion, opioid consumption, postoperative pain scores, sleep disturbance, and time to discharge as well as the occurrence of postoperative systemic complications.

RESULTS

Of the 240 patients randomly assigned to the 2 treatment groups (120 in each), data for the primary outcome were obtained from 113 pregabalin patients and 115 placebo patients. At both 3 and 6 mo postoperatively, the incidence of neuropathic pain was less frequent in the pregabalin group (0%) compared with the placebo group (8.7% and 5.2% at 3 and 6 mo, respectively; P = 0.001 and P = 0.014). Patients receiving pregabalin also consumed less epidural opioids (P = 0.003), required less oral opioid pain medication while hospitalized (P = 0.005), and had greater active flexion over the first 30 postoperative days (P = 0.013). There were no differences in the actual recorded duration of hospitalization between the 2 groups, although time to achieve hospital discharge criteria was longer for placebo patients, 69.0 +/- 16.0 h (mean +/- SD), than that of pregabalin patients, 60.2 +/- 15.8 h (P = 0.001). Sedation (P = 0.005) and confusion (P = 0.013) were more frequent on the day of surgery and postoperative day 1 in patients receiving pregabalin.

CONCLUSION

Perioperative pregabalin administration reduces the incidence of chronic neuropathic pain after TKA, with less opioid consumption and better range of motion during the first 30 days of rehabilitation. However, in the doses tested, it is associated with a higher risk of early postoperative sedation and confusion.

The variation in medial and lateral collateral ligament strain and tibiofemoral forces following changes in the flexion and extension gaps in total knee replacement

Achieving deep flexion after total knee replacement remains a challenge. In this study we compared the soft-tissue tension and tibiofemoral force in a mobile-bearing posterior cruciate ligament-sacrificing total knee replacement, using equal flexion and extension gaps, and with the gaps increased by 2 mm each. The tests were conducted during passive movement in five cadaver knees, and measurements of strain were made simultaneously in the collateral ligaments. The tibiofemoral force was measured using a customised mini-force plate in the tibial tray. Measurements of collateral ligament strain were not very sensitive to changes in the gap ratio, but tibiofemoral force measurements were. Tibiofemoral force was decreased by a mean of 40% (sd 10.7) after 90° of knee flexion when the flexion gap was increased by 2 mm. Increasing the extension gap by 2 mm affected the force only in full extension. Because increasing the range of flexion after total knee replacement beyond 110° is a widely-held goal, small increases in the flexion gap warrant further investigation.