Clinical and functional comparison of bicondylar sledge prostheses retaining all ligaments and constrained total knee replacement

Outcomes of Bi-unicompartmental Versus Total Knee Arthroplasty for the Treatment of Medial and Lateral Knee Osteoarthritis: A Systematic Review and Meta-analysis of Comparative Studies

PURPOSE

The aim of this meta-analysis was to evaluate differences in functional outcomes between simultaneous bi-unicompartmental knee arthroplasty (Bi-UKA) and total knee arthroplasty (TKA) for the treatment of medial and lateral knee osteoarthritis.

MATERIAL AND METHODS

According to the PRISMA statement, a comprehensive search was conducted to identify studies reporting comparative results of the Bi-UKA versus the TKA. Of 953 titles, 6 studies met the inclusion criteria.

RESULTS

A total of 286 patients were identified, of which 137 underwent Bi-UKA and 149 TKA. TKA reported a mean hip-knee-ankle (HKA) angle of 179.4 ± 2.4 compared to that in Bi-UKA measuring 177.2 ± 2.7 (p = 0.0001, 95% CI - 3.02 to - 1.38). No difference was found in the Western Ontario and McMaster Universities (WOMAC) pain (4 ± 1.6 and 4.2 ± 1.3 for Bi-UKA and TKA, respectively; p = 0.4996, 95% CI - 0.86 to 0.43). Bi-UKA was favorable in terms of WOMAC function (7.5 ± 1.9 and 9 ± 1.9 for Bi-UKA and TKA, respectively; p = 0.001, 95% CI - 2.29 to - 0.61) and WOMAC stiffness (1.6 ± 1 and 2.4 ± 0.7 for Bi-UKA and TKA, respectively; p = 0.0001, 95% CI - 1.18 to - 0.42). Bi-UKA showed a better Knee Society Score (KSS) in comparison to TKA (79.7 ± 7.8 and 75.4 ± 10.5 for Bi-UKA and TKA, respectively; p = 0.0021, 95% CI 1.58-7.02). The differences in postoperative outcomes scores between Bi-UKA and TKA were lower than their respective minimum clinically important differences.

CONCLUSIONS

When Bi-UKA and TKA are compared for the treatment of medial and lateral knee osteoarthritis, Bi-UKA are favorable in terms of WOMAC and KSS even though these values are lower than the minimum clinically important differences; moreover, similar postoperative hip-knee-ankle angle can be expected 3 years after Bi-UKA and TKA.

Relevant changes of leg alignment after customised individually made bicompartmental knee arthroplasty due to overstuffing

PURPOSE

The purpose of this study is to analyse the change in knee alignment after customised individually made (CIM) bicompartmental knee arthroplasty (BKA) and the subsequent consequences for patellar tracking.

METHODS

Medical records of 23 patients who received 26 CIM BKA (ConforMIS iDuo G2) at our clinic between November 2015 and July 2018 were reviewed. The objective part of the Knee Society Score (KSS), the hip-knee-ankle angle (HKA), the tibial mechanical angle (TMA) and femoral mechanical angle (FMA) were recorded preoperative and four months postoperative. Leg alignment was classified as neutral (HKA = 180° ± 3°), varus (HKA < 177°) or valgus (HKA > 183°). Furthermore, patellar tracking was determined on skyline view radiographs and adverse events were recorded. Implant survival rate was determined with the Kaplan-Meier method. Patient-reported outcome measures (PROMs) were pain, satisfaction, overall improvement and if the patient would undergo the surgery again.

RESULTS

The mean KSS improved from 61 points preoperative [standard deviation (SD) 14] to 90 points postoperative (SD 7, p < 0.001). The mean change for HKA was 6.3° (SD 3.5), for TMA 1.5° (SD 1.2) and for FMA 3.8° (SD 2.3). Postoperative leg alignment was neutral in 13 CIM BKA (50%), varus in two (8%) and valgus in 11 (42%) and patella tracking was central in 19 CIM BKA (73%) and lateral in seven (27%), respectively. Adverse events occurred in five CIM BKA: three patients required a patella resurfacing and one patient with bilateral CIM BKA needed a revision to a total knee arthroplasty. Implant survival rate was 92.3% at a follow-up of 3.2 years (SD 0.8). PROMs for CIM BKA without revision surgery were available at a mean follow-up of 3.2 years (SD 0.8). Mean pain with level walking decreased to 0.8 points (SD 1.4, p < 0.001) and mean pain with stairs or inclines to 1.6 points (SD 1.3, p < 0.001). Patient satisfaction was very satisfied or satisfied (78%), neutral (17%) or unsatisfied (4%). Overall improvement was much better or considerably better for 91% of all patients; 87% would undergo the surgery again.

CONCLUSION

A relevant change of the leg axis away from the treated femorotibial compartment due to overstuffing was observed. Although, neutral leg alignment was not restored in every case, clinical and patient-reported outcomes improved significantly. Further studies with long-term clinical and patient-reported outcomes are required to evaluate whether patients with bicompartmental knee osteoarthritis benefit from CIM BKA.

LEVEL OF EVIDENCE

IV, case series.

Ten year outcomes for the prospective randomised trial comparing unlinked, modular bicompartmental knee arthroplasty and total knee arthroplasty

BACKGROUND

A sizeable proportion of knee osteoarthritis is limited to the medial and patellofemoral compartments. Whilst short- and medium-term studies comparing bicompartmental knee arthroplasty (BCA) and total knee arthroplasty (TKA) have shown similar outcome scores, there are no studies comparing long-term outcomes. This study aims to determine which procedure resulted in superior long-term outcome scores.

METHODS

Forty-eight patients with medial and patellofemoral compartment knee osteoarthritis were randomised to receive treatment in two groups: unlinked, modular BCA and TKA. The main outcome measures compared were the range of motion, Knee Society Function Score, Knee Society Knee Score, Oxford Knee Score, Physical Component Score and Mental Component Score of SF-36 pre-operatively and post-operatively up to 10 years. Radiographs of the operated knees were taken pre-operatively, post-operatively and at 10-year follow-up.

RESULTS

Twenty-six underwent BCA and 22 underwent TKA. Overall improvement was seen in both groups compared to pre-operatively, however there were no significant differences detected between the groups at 10 years. The median Hip-Knee-Ankle (HKA) angle was 183.38 (175.17-187.94) in the BCA group and 180.73 (174.96-185.65) in the TKA group. One patient from the BCA group had a peri-prosthetic fracture necessitating revision surgery to a TKA.

CONCLUSIONS

Outcome scores for BCA results were comparable to TKA at long-term follow-up. BCA is an alternative arthroplasty option in selected patients.

Clinical outcome of bi-unicompartmental knee arthroplasty for both medial and lateral femorotibial arthritis: a systematic review-is there proof of concept?

INTRODUCTION

Unicompartmental knee arthroplasty (UKA) is a well-accepted treatment for isolated unicompartmental osteoarthritis (OA) of the knee. In previous literature, it has been suggested that bi-unicompartmental knee arthroplasty (bi-UKA) which uses two UKA implants in both the medial and lateral compartments of the same knee is a feasible and viable option for the treatment of knee OA. Given the advantages of UKA treatment, it is warranted to review the literature of bi-UKA and discuss the evidence in terms of implant selection, indications, surgical techniques, and outcomes, respectively.

MATERIALS AND METHODS

Following the PRISMA guidelines, PubMed, Medline, Embase, CINAHL, Web of Science, and Cochrane Library were searched for studies presenting outcome of bi-UKA. Studies were included if they reported clinical outcomes using two unicompartmental prostheses for both medial and lateral femorotibial arthritis. Studies with the addition of patellofemoral arthroplasty or concomitant soft-tissue reconstruction and those not published in English were excluded.

RESULTS

In the early literature, the procedure of bi-UKA were performed for very severe OA and rheumatoid arthritis, but indications have evolved to reflect a more contemporary case-mix of knee OA patients. Both mobile and fixed bearing implants have been used, with the latter being the most frequent choice. A medial parapatellar approach for incision and arthrotomy has been the most frequently used technique. The present review found a promising clinical outcome of both simultaneous and staged bi-UKA although the number of long-term follow-up studies was limited.

CONCLUSIONS

Both simultaneous and staged bi-UKA has demonstrated good functional outcomes. However, the volume and level of evidence in general is low for studies captured in this review, and the data on long-term outcomes remain limited. The present review indicates that bi-UKA is a feasible and viable surgical option for bicompartmental femorotibial OA in carefully selected patients.

Normalized gait analysis parameters are closely related to patient-reported outcome measures after total knee arthroplasty

Up till now, only a weak connection could be shown between patient-related outcome measures (PROMs) and measurements obtained by gait analysis (e.g. speed, step length, cadence, ground reaction force, joint moments and ranges of motion) after total knee arthroplasty (TKA). This may result from the methodical problem that regression analyses are performed using data that are not normalized against a healthy population. It does appear reasonable to assume that patients presenting a physiological gait pattern are content with their joint. The more the gait parameters differ from a normal gait pattern the worse the clinical outcome measured by PROMs should be expected to be. In this retrospective study, 40 patients were enrolled who had received a gait analysis after TKA, and whose PROMs had been evaluated. A gender- and age-matched control group was formed out of a group of test persons who had already undergone gait analysis. Gait analysis was undertaken using the motion analysis system 3D Vicon with ten infrared cameras and three strength measuring force plates. The physiological gait analysis parameters were deduced from arithmetic mean values taken from all control patients. The deviances of the operated patients' gait analysis parameters from the arithmetic mean values were squared. From these values, the Pearson correlation coefficients for different PROMs were then calculated, and regression analyses were performed to elucidate the correlation between the different PROMs and gait parameters. In the regression analysis, the normalized cadence, relative gait speed of the non-operated side, and range of the relative knee moment of the operated side could be identified as factors which influence the Forgotten Joint Score (FJS-12). The explanation model showed an increase of the FJS-12 with minimisation of these normalized values corresponding to an approximation of the gait pattern seen in the healthy control group. The connection was strong, having a correlation coefficient of 0.708. A physiological gait pattern after TKA results in better PROMs, especially the FJS-12, than a non-physiological gait pattern does.

Bicompartmental (uni plus patellofemoral) versus total knee arthroplasty: a match-paired study

BACKGROUND

Osteoarthritis (OA) of the knee, whether primary or post-traumatic, does not always involve all three compartments (tibiofemoral medial and lateral and the patellofemoral ones). Bicompartmental knee arthroplasty (BKA) was proposed as a good alternative to total knee arthroplasty when two of the three knee compartments were affected.

MATERIALS AND METHODS

We performed a retrospective comparative study collecting all BKAs performed between March 2010 and January 2016. During this period, we treated 27 patients with BKA for medial or lateral and patellofemoral OA. Seven of them were lost to follow-up and were not included in the study. Group A (BKA group) was compared to a homogeneous group of 20 patients who underwent TKA during the same period (group B).

RESULTS

Patients treated with TKA were younger than those treated with BKA (mean age 65 vs. 67.2; p = 0.2149). BKA resulted in longer mean operating time (87 vs. 82.4 min; p = 0.2983), less blood loss (413 vs. 458 ml; p = 0.0052) but higher blood transfusion rate (12 vs. 10%). Medium follow-up was 34 months for BKA group and 38 months for TKA group. No statistically significant differences were found in KSS score between the two groups (KSS score 92.3 for BKA, 94.5 for TKA; p = 0.5221; KSS function was 87.2 for BKA and 89.2 for TKA; p = 0.4985).

CONCLUSION

The most important finding of the present study was that although BKA seemed to be theoretically more favorable in terms of functional recovery and blood loss, patients of group A had lower KSS score and higher transfusion rate than those of group B. Our data confirm that BKA could be proposed as an alternative to TKA, especially in young and high-demanding patients.

Proprioception after bicruciate-retaining total knee arthroplasty is comparable to unicompartmental knee arthroplasty

PURPOSE

Rising expectations in functional performance of total knee joints are inciting further improvement of knee arthroplasty implants. From a patient-centred view, bicruciate-retaining models provide a more natural feeling knee. However, there is no evidence of functional advantage for these implants. The aim of this study was to evaluate balance ability as a measure of proprioception in patients with a bicruciate-retaining total knee arthroplasty.

METHODS

A prospective, controlled trial was conducted to compare balance ability in 60 patients after arthroplasty of the knee for osteoarthritis. We compared patients with a bicruciate-retaining knee arthroplasty (BCR group) to a control group of patients with a medial unicompartmental knee arthroplasty (UKA group) and another control group of patients with a posterior stabilized total knee arthroplasty (PS group). The patient population comprised 30 women (50.0 %) and 30 men in three cohorts of 20 each. The mean age was 62.1 ± 8.0 years (range 43-78). Patients were evaluated preoperatively and 9 months post-operatively. The evaluation included clinical, radiological, and balance testing-a single-leg stance with eyes closed compared to eyes open. The difference in area of sway between eyes closed and eyes open represents static balance ability after knee arthroplasty.

RESULTS

Perioperative data showed that there was no intra-operative fracture of the intercondylar eminence. There was a decreased post-operative knee extension 9 months post-operative in the BCR group, which was not clinically relevant in any case. We recorded a lower difference in the area of sway between eyes closed and eyes open (ΔA _(ec-eo)) for the BCR group (p = 0.01) and the UKA group (p = 0.04) compared to the PS group.

CONCLUSIONS

This study found superior static balance ability after preservation of both cruciate ligaments in arthroplasty of the knee, indicating superior proprioceptive function. Hence, BCR implants could provide improved functional properties. Superior proprioceptive function of bicruciate-retaining implants can be an important factor in implant selection. Further prospective, randomized studies to investigate kinematics and long-term survivorship of bicruciate-retaining implants are needed.

LEVEL OF EVIDENCE

II.

Knee Extensor Strength and Gait Characteristics After Minimally Invasive Unicondylar Knee Arthroplasty vs Minimally Invasive Total Knee Arthroplasty: A Nonrandomized Controlled Trial

BACKGROUND

In light of the existing lack of evidence, it was the aim of this study to compare gait characteristics and knee extensor strength after medial unicondylar knee arthroplasty (MUKA) with those after total knee arthroplasty (TKA), given the same standardized minimally invasive surgery (MIS) approach in both groups.

METHODS

Patients scheduled for MIS-MUKA or MIS-TKA as part of clinical routine were invited to participate. A posterior cruciate ligament-retaining total knee design was used for all MIS-TKA. A 3-dimensional gait analysis was performed preoperatively with a VICON system and at 8 weeks postoperative to determine temporospatial parameters, ground reaction forces, joint angles, and joint moments. At the same 2 times, isokinetic tests were performed to obtain peak values of knee extensor torque. A multivariate analysis of variance was conducted and included the main effects time (before and after surgery) and surgical group and the group-by-time interaction effect.

RESULTS

Fifteen MIS-MUKA patients and 17 MIS-TKA patients were eligible for the final analysis. The groups showed no differences regarding age, body mass index, sex, side treated, or stage of osteoarthritis. We determined neither intergroup differences nor time × group interactions for peak knee extensor torque or any gait parameters (temporospatial, ground reaction forces, joint angles, and joint moments).

CONCLUSION

It is concluded that MUKA is not superior to TKA with regard to knee extensor strength or 3-dimensional gait characteristics at 8 weeks after operation. As gait characteristics and knee extensor strength are only 2 of the various potential outcome parameters (knee scores, activity scores…) and quadriceps strength might take a longer time to recover, our findings should be interpreted with caution.

Bicompartmental knee arthroplasty

Total knee arthroplasty (TKA) is the most worldwide practiced surgery for knee osteoarthritis and its efficacy is mightily described by literature. Concerns about the invasiveness of TKA let the introduction of segmental resurfacing of the joint for younger patients with localized osteoarthritis. Bone stock sparing and ligaments preservation are the essence of both unicompartmental knee arthroplasty (UKA) and bicompartmental knee arthroplasty (BKA). Advantages related to BKA are the respect of knee biomechanics, lower complications rates, shorter hospital stay, faster rehabilitation. Moreover, in case of failure of the first implant the conversion to TKA is undemanding and can be compared to a standard prosthesis. Our experience suggest that BKA is a reliable technique in selected cases and especially younger people with higher functional requests can favourably profit from it. Although those results are encouraging, we still need further prospective, randomized, long-term studies to finally assess BKA indications and outcomes.

Fracture of the Tibial Baseplate in Bicompartmental Knee Arthroplasty

Introduction. Bicompartmental knee arthroplasty (BKA) addresses combined medial and patellofemoral compartment osteoarthritis, which is relatively common, and has been proposed as a bridge between unicompartmental and total knee arthroplasty (TKA). Case Presentation. We present the case report of a young active man treated with BKA after unsuccessful conservative therapy. Four years later, loosening with fracture of the tibial baseplate was identified and the patient was revised to TKA. Discussion. Although our case is only the second fractured tibial baseplate to be reported, we believe that the modular titanium design, with two fixation pegs, is too thin to withstand daily cyclic loading powers. Light daily routine use, rather than high-impact sports, is therefore advised. Failures may also be related to the implant being an early generation and known to be technically complex, with too few implant sizes. We currently use TKA for the treatment of medial and patellofemoral compartment osteoarthritis.

Prospective randomised trial comparing unlinked, modular bicompartmental knee arthroplasty and total knee arthroplasty: a five years follow-up

BACKGROUND

A significant proportion of patients with knee osteoarthritis have articular degeneration that is limited to the medial and patellofemoral compartments. The objective of this study was to compare clinical outcomes of unlinked bicompartmental knee arthroplasty (BCA) and total knee arthroplasty (TKA) at 5years in this subset of patients.

METHODS

48 patients were randomised into two groups: unlinked, modular bicompartmental arthroplasty and total knee arthroplasty. Data on demographics and clinical outcomes were collected (Bartlett Knee Score, Oxford Knee Score, Knee Society Score). Data on intra-operative blood loss in both groups were also recorded.

RESULTS

Out of the 48 patients, 26 underwent BCA and 22 had TKA. Both groups shared similar demographic profiles. At five years post surgery, there was significant improvement across all functional scores in both groups. However, there was no significant difference in outcome scores in the BCA group compared to the TKA group. The drop in serum haemoglobin levels postoperatively was 1.55 and 2.30g/dl for the BCA and TKA groups respectively (p<.001). The total amount of blood loss was 397 and 647ml respectively (p=.001).

CONCLUSIONS

Unlinked, modular BCA results in similar clinical and functional scores as TKA for medial and patellofemoral arthritis in the mid-term. Intra-operative blood loss was significantly lower in the BCA group compared to the TKA group. BCA is a viable option for a select group of young and active patients with the advantage of reduced intra-operative blood loss and equivalent functional outcomes as TKA.

Motion analysis of patients after knee arthroplasty during activities of daily living--a systematic review

BACKGROUND

Motion analysis with optoelectronic systems is a frequently used method to analyze the patient's gait as well as further relevant activities of daily living before and after knee arthroplasty. The aim of this systematic review was to identify the investigated activities of daily living and to show an extensive presentation of gait analysis studies with patients after knee arthroplasty surgery.

METHODS

The articles were searched in electronic databases: MEDPILOT, EMBASE. To identify articles that potentially met the inclusion criteria the titles and abstracts were screened. The level of evidence was analyzed for the included articles.

RESULTS

Overall 3989 abstracts were reviewed and 87 full text articles were included. Ten activities of daily living were identified. Level walking was the most frequently investigated activity (78.2%). In 94.6% the sagittal plane kinematics were analyzed and 5.3% presented the results in all three planes. Knee adduction moments were determined in 33.3% of the included articles. At least two joints were investigated in 40.2%, including the impaired knee and further body parts (ankle, hip, pelvis, trunk). Unicondylar knee arthroplasty was addressed in 14.1%.

CONCLUSIONS

Besides level walking, it is necessary to examine physical more demanding activities of daily living to detect potential kinematic and kinetic abnormalities. Further research should imply the evaluation of sagittal, frontal and transverse plane joint and muscle function based on accurate inverse-dynamic techniques. More motion analysis studies are necessary that address unicondylar knee arthroplasty in comparison to total knee arthroplasty and healthy controls.

Lower limb strength following total knee arthroplasty: a systematic review

BACKGROUND

Total knee arthroplasty (TKA) is commonly performed for end-stage knee osteoarthritis to relieve pain and improve quality of life. Understanding specific muscle weakness following TKA is required in order to develop targeted rehabilitation programmes for TKA patients. The aim of this systematic review was to determine whether TKA patients have reduced strength in lower limb muscle groups compared to controls.

METHODS

A search of common scientific databases was conducted. A modified published checklist was used to assess the risk of bias. A meta-analysis was completed for each lower limb muscle group in three separate post-operative time periods (4-6 months, 1-3 years, and >3 years). The GRADE approach was used to determine the quality of the evidence.

RESULTS

Fifteen studies met the inclusion criteria for this review. There was low quality evidence for all meta-analyses. The meta-analyses showed that TKA patients had weaker quadriceps than the controls at every post-operative time (pooled effect sizes between -2.81 and -0.53). The meta-analyses of hamstring strength for patients 1-3 years post-operatively also showed patient weakness (pooled effect size=-1.87) and no significant difference at >3 years post-operatively (pooled effect size=-0.20).

CONCLUSION

There was low quality evidence of quadriceps and hamstring weakness following TKA. Further research is required to determine if other lower limb muscles also display similar muscle weakness. Strategies that specifically target strengthening of these muscle groups may need to be incorporated in rehabilitation to improve outcomes from TKA.

LEVEL OF EVIDENCE

I.

Quadriceps force after TKA with femoral single radius

BACKGROUND AND PURPOSE

New implant designs have incorporated a single radius instead of a multiple radius to the femoral component in order to improve the mechanical function after TKA. We investigated the amount of quadriceps force required to extend the knee during an isokinetic extension cycle of different total knee designs, focusing on the radius of the femoral component (single vs. multiple).

METHODS

Human knee specimens (n = 12, median patient age 68 (63-70) years) were tested in a kinematic knee-simulating machine untreated and after implantation of 2 types of knee prosthesis systems, one with a single femoral radius design and one with a multiple femoral radius design. During the test cycle, a hydraulic cylinder, which simulated the quadriceps muscle, applied sufficient force to the quadriceps tendon to produce a constant extension moment of 31 Nm. The quadriceps extension force was measured from 120° to full knee extension.

RESULTS

The shape of the quadriceps force curve was typically sinusoidal before and after TKA, reaching a maximum value of 1,493 N at 110°. With the single femoral radius design, quadriceps force was similar to that of the normal knee: 1,509 N at 110° flexion (p = 0.4). In contrast, the multiple femoral radius design showed an increase in quadriceps extension force relative to the normal knee, with a maximum of 1,721 N at 90° flexion (p = 0.03).

INTERPRETATION

The single femoral radius design showed lower maximum extension forces than the multiple femoral radius design. In addition, with the single femoral radius design maximum quadriceps force needed to extend a constant extension force shifted to higher degrees of knee flexion, representing a more physiological quadriceps force pattern, which could have a positive effect on knee function after TKA.

Knee kinematics during walking at different speeds in people who have undergone total knee replacement

People who have undergone total knee replacement (TKR) experience difficulties in some daily activities including walking. Walking at faster speeds requires more knee flexion and may therefore present a greater challenge following TKR. The aim of this study was to compare the knee kinematics of patients following TKR and unimpaired controls during comfortable and fast walking speeds. Forty patients (22 women, 18 men) 12 months following TKR and 40 control participants (matched for age and sex) were assessed during walking at self-selected comfortable and fast speeds using three dimensional motion analysis. The group averages of spatiotemporal and peak kinematic characteristics in the sagittal, coronal and transverse movement planes were compared using univariate analysis of variance with walking speed as a co-variate. The TKR group walked with significantly reduced cadence (p < 0.001 at both speeds) and reduced stride length (p < 0.001 at both speeds), less knee flexion during stance and swing phases (p < 0.001 for both speeds) and less knee extension during stance phase (p < 0.024 for comfortable speed; p < 0.042 for fast speed). The TKR group also walked with less peak knee external rotation than controls at both speeds (p < 0.001 for both speeds). Both groups increased their velocity, cadence and stride length by a similar proportion when walking at fast speed. When walking at a faster speed, spatiotemporal gait parameters and knee motion are altered in a similar manner for both TKR patients and controls. However, at both walking speeds, TKR patients exhibit residual deficits 12 months following surgery.

Acceleration-based motion analysis as a tool for rehabilitation: exploration in simulated functional knee limited walking conditions

OBJECTIVE

The aim of this study was to investigate the ability of acceleration-based gait analysis to differentiate between normal gait and different simulated functional knee limitations of increasing severity.

DESIGN

Gait of 48 healthy subjects was measured under four different walking conditions. Gait parameters (e.g., speed and asymmetry) were derived from trunk accelerations. Subjects walked a 20-m distance under four conditions: normal, simulated limited knee extension, simulated limited knee flexion, and simulated arthrodesis. The functional knee limitations were simulated using an adjustable knee brace on the right leg.

RESULTS

Acceleration-based gait analysis detected acute gait changes (i.e., speed, step length, step duration, cadence, vertical displacement, asymmetry, and irregularity) during the simulated functional knee limitations with high repeatability. The degree of change depended on the severity of the limitation, with the more severe limitations producing bigger changes in gait and the relative changes comparing well with literature values measured with laboratory-based motion analysis.

CONCLUSIONS

Acceleration-based gait analysis is sensitive for different walking conditions. The easy and fast use, the production of objective gait characteristics, and the ability to differentiate functional knee limitations suggest its suitability for clinical rehabilitation.

Survival of bicompartmental knee arthroplasty at 5 to 23 years

Recent literature suggests patients achieve substantial short-term functional improvement after combined bicompartmental implants but longer-term durability has not been documented. We therefore asked whether (1) bicompartmental arthroplasty (either combined medial unicompartmental knee arthroplasty (UKA) and femoropatellar arthroplasty (PFA) or medial UKA/PFA, or combined medial and lateral UKA or bicompartmental UKA) reliably improved Knee Society pain and function scores; (2) bicompartmental arthroplasty was durable (survivorship, radiographic loosening, or symptomatic disease progression); (3) we could achieve durable alignment; and (4) the arthritis would progress in the unresurfaced compartment. We retrospectively reviewed 84 patients (100 knees) with bicompartmental UKA and 71 patients (77 knees) with medial UKA/PFA. Clinical and radiographic evaluations were performed at a minimum followup of 5 years (mean, 12 years; range, 5-23 years). Bicompartmental arthroplasty reliably alleviated pain and improved function. Prosthesis survivorship at 17 years was 78% in the bicompartmental UKA group and 54% in the medial UKA/PFA group. The high revision rate, compared with total knee arthroplasty, may be related to several factors such as implant design, patient selection, crude or absent instrumentation, or component malalignment, which can all contribute to the relatively high failure rate in this series.

LEVEL OF EVIDENCE

Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Correlation between objective gait parameters and subjective score measurements before and after total knee arthroplasty

The absence of uniformity, the use of different terminologies, and the diversity of methods used to translate numerical data into clinical outcomes have been described as potential problems when dealing with clinical knee scores for total knee arthroplasty (TKA). Gait analysis is believed to provide more objective parameters. The aim of the present study was to obtain information about the correlation between the outcome in terms of locomotion and the clinical knee score after TKA. Thirty consecutive patients awaiting TKA were involved in the study. One day prior to surgery and 3 months postoperatively, data pertaining to the Hospital for Special Surgery Score (HSS) and the Knee Society Score (KSS) (subgroups 'pain', 'knee', 'function' and 'total sum') were analyzed for correlations with kinematic and temporospatial parameters of gait analysis. At a significance-level of p</=0.001 moderate correlations (0.4<r<0.6) were found preoperatively, particularly between 'max knee flexion swing' and the function-subscores of HSS and KSS and the 'KSS total'. High correlations (0.6<r<0.8) were ascertained for 'stride length' and 'gait velocity' with 'KSS function'. High correlations were also determined between 'stride length' and 'KSS total' and between 'gait velocity' and 'HSS function'. The only correlation found postoperatively was between 'max pelvic obliquity stance' and 'KSS knee' (r=0.770, p<0.001). We conclude that the 'function' subscores of KSS and HSS are highly suitable to assess the functional capacity of patients scheduled for TKA. However, because no adequate correlations between knee scores and gait parameter were found postoperatively, we cannot recommend the abandonment of gait analysis when monitoring the functional benefit of TKA.

Quantity versus quality of gait and quality of life in patients with osteoarthritis

PURPOSE

This study investigated the relationship between the quality of life, quality of gait and the quantity of gait in patients with impairments in the lower extremities.

METHODS

Twenty-six subjects (age 58.6+/-13.4 years) suffering from knee or hip osteoarthritis were investigated before implantation of an endoprosthesis. Quality of life was assessed using the SF-36 survey. The quality of gait was assessed with a six camera motion analysis system in combination with two force plates. For evaluation of the quantity of gait, two monitors were applied: (a) the accelerometer-based DynaPort activity monitor measured locomotion and posture for 1 day and (b) The Step-Activity-Monitor, a small microprocessor-operated acceleration sensor, measured the number of gait cycles in 1-min intervals for 1 week. Spearman correlation coefficients were calculated between quantity of gait, quality of gait and quality of life.

RESULTS

The patients showed typical gait impairments caused by osteoarthritis. Locomotion accounted for 10.5+/-5% of the daily recorded time, 4782+/-2116 gait cycles were counted per day. The sub-categories of the SF-36 showed limited physical functioning and general health with 38 and 56 out of 100 points, respectively. Computation of Spearman-rho revealed no relevant correlations between quality and quantity of gait but moderate correlations between quality of life and quantity of gait.

CONCLUSION

The findings underline that a patient's level of mobility cannot be reliably estimated from quality of gait or from quality of life. Instead, adequate methods should be chosen to measure the quantity of gait in daily life.

Quadriceps force during knee extension after non-hinged and hinged TKA: an in vitro study

BACKGROUND AND PURPOSE

Problems during knee extension, due to kinematic alterations, are not uncommon after total knee arthroplasty. Hinged prostheses provide higher stability than non-hinged designs and may minimize these alterations. Thus, in this in vitro study we investigated the quadriceps force required to extend the knee during an isokinetic extension cycle generating a constant extension moment after non-hinged and hinged total knee arthroplasty.

METHODS

Human knee specimens were tested in a kinematic knee simulator under physiological conditions, after implantation of two types of non-hinged cruciate retaining prosthesis (Gemini; Link, Germany and Interax I.S.A.; Stryker, Ireland) and a hinged prosthesis (Rotations-Knie; Link, Germany). During simulation of an extension cycle from 120 degrees knee flexion to full extension, the change in quadriceps force to produce the constant extension moment of 31 Nm was dynamically measured using a load cell attached to the quadriceps tendon.

RESULTS

After implantation of the non-hinged pros-theses, there was no alteration in maximum quadriceps force in knee flexion compared to physiological conditions, but alteration occurred at lower flexion angle (p=0.002) and increased up to 1,257 (SD 273) N (p=0.04) in knee extension. Following implantation of the hinged prosthesis, there was no alteration in quadriceps extension force in flexion but it decreased to 690 (SD 81) N (p=0.003) in extension.

INTERPRETATION

Hinged knee prostheses restore the quadriceps lever arm in knee flexion and improve the lever arm in knee extension due to higher constraint and knee joint stability. This would offer a potential advantage for patients with weak quadriceps strength by making it easier to stabilize the knee in full extension during walking.

Gait analysis of patients following total knee replacement: a systematic review

Gait analysis has been used to objectively measure patients' function following total knee replacement (TKR). Whilst the findings of this research may have important implications for the understanding of the outcomes of TKR, the methodology of existing research appears to be diverse and many of the results inconsistent. The objective of this systematic review was to synthesise reported findings and to summarise the methods used by researchers in this field. Eleven articles published in the medical literature that used gait analysis to compare patients following TKR with controls were identified for inclusion in this review. Each article was assessed for methodologic quality and data was compared across studies through the calculation of effect sizes. Consistently large effect sizes showed that patients following TKR walk with less total knee motion during gait and with less knee flexion during swing than controls. Kinetic discrepancies between patients and controls were also identified. The substantial methodologic differences between studies may contribute to the inconsistencies in reported findings for many gait outcomes. Future research is needed to determine the clinical relevance of these findings.