Patella retention versus replacement in total knee arthroplasty; functional and clinimetric aspects

Postoperative Activity and Knee Function of Patients after Total Knee Arthroplasty: A Sensor-Based Monitoring Study

Inertial measurement units (IMUs) are increasingly being used to assess knee function. The aim of the study was to record patients' activity levels and to detect new parameters for knee function in the early postoperative phase after TKA. Twenty patients (n = 20) were prospectively enrolled. Two sensors were attached to the affected leg. The data were recorded from the first day after TKA until discharge. Algorithms were developed for detecting steps, range of motion, horizontal, sitting and standing postures, as well as physical therapy. The mean number of steps increased from day 1 to discharge from 117.4 (SD ± 110.5) to 858.7 (SD ± 320.1), respectively. Patients' percentage of immobilization during daytime (6 a.m. to 8 p.m.) was 91.2% on day one and still 69.9% on the last day. Patients received daily continuous passive motion therapy (CPM) for a mean of 36.4 min (SD ± 8.2). The mean angular velocity at day 1 was 12.2 degrees per second (SD ± 4.4) and increased to 28.7 (SD ± 16.4) at discharge. This study shows that IMUs monitor patients' activity postoperatively well, and a wide range of interindividual motion patterns was observed. These sensors may allow the adjustment of physical exercise programs according to the patient's individual needs.

Isolated effects of patellar resurfacing in total knee arthroplasty and their relation to native patellar geometry

The isolated effects of patellar resurfacing on patellar kinematics are rarely investigated. Nonetheless, knowing more about these effects could help to enhance present understanding of the emergence of kinematic improvements or deteriorations associated with patellar resurfacing. The aim of this study was to isolate the effects of patellar resurfacing from a multi-stage in vitro study, where kinematics after total knee arthroplasty before and after patellar resurfacing were recorded. Additionally, the influence of the native patellar geometry on these effects was analysed. Eight fresh frozen specimens were tested successively with different implant configurations on an already established weight bearing knee rig. The patello-femoral kinematics were thereby measured using an ultrasonic measurement system and its relation to the native patellar geometries was analysed. After patellar resurfacing, the specimen showed a significantly medialized patellar shift. This medialization of the patellar tracking was significantly correlated to the lateral facet angle of the native patella. The patellar shift after patellar resurfacing is highly influenced by the position of the patellar button and the native lateral patellar facet angle. As a result, the ideal medio-lateral position of the patellar component is affected by the geometry of the native patella.

Remote Patient Monitoring with Wearable Sensors Following Knee Arthroplasty

(Background) Inertial Measurement Units (IMUs) provide a low-cost, portable solution to obtain functional measures similar to those captured with three-dimensional gait analysis, including spatiotemporal gait characteristics. The primary aim of this study was to determine the feasibility of a remote patient monitoring (RPM) workflow using ankle-worn IMUs measuring impact load, limb impact load asymmetry and knee range of motion in combination with patient-reported outcome measures. (Methods) A pilot cohort of 14 patients undergoing primary knee arthroplasty for osteoarthritis was prospectively enrolled. RPM in the community was performed weekly from 2 up to 6 weeks post-operatively using wearable IMUs. The following data were collected using IMUs: mobility (Bone Stimulus and cumulative impact load), impact load asymmetry and maximum knee flexion angle. In addition, scores from the Oxford Knee Score (OKS), EuroQol Five-dimension (EQ-5D) with EuroQol visual analogue scale (EQ-VAS) and 6 Minute Walk Test were collected. (Results) On average, the Bone Stimulus and cumulative impact load improved 52% (p = 0.002) and 371% (p = 0.035), compared to Post-Op Week 2. The impact load asymmetry value trended (p = 0.372) towards equal impact loading between the operative and non-operative limb. The mean maximum flexion angle achieved was 99.25° at Post-Operative Week 6, but this was not significantly different from pre-operative measurements (p = 0.1563). There were significant improvements in the mean EQ-5D (0.20; p = 0.047) and OKS (10.86; p < 0.001) scores both by 6 weeks after surgery, compared to pre-operative scores. (Conclusions) This pilot study demonstrates the feasibility of a reliable and low-maintenance workflow system to remotely monitor post-operative progress in knee arthroplasty patients. Preliminary data indicate IMU outputs relating to mobility, impact load asymmetry and range of motion can be obtained using commercially available IMU sensors. Further studies are required to directly correlate the IMU sensor outputs with patient outcomes to establish clinical significance.

Wearable Inertial Sensors for Gait Analysis in Adults with Osteoarthritis-A Scoping Review

Our objective was to conduct a scoping review which summarizes the growing body of literature using wearable inertial sensors for gait analysis in lower limb osteoarthritis. We searched six databases using predetermined search terms which highlighted the broad areas of inertial sensors, gait, and osteoarthritis. Two authors independently conducted title and abstract reviews, followed by two authors independently completing full-text screenings. Study quality was also assessed by two independent raters and data were extracted by one reviewer in areas such as study design, osteoarthritis sample, protocols, and inertial sensor outcomes. A total of 72 articles were included, which studied the gait of 2159 adults with osteoarthritis (OA) using inertial sensors. The most common location of OA studied was the knee (n = 46), followed by the hip (n = 22), and the ankle (n = 7). The back (n = 41) and the shank (n = 40) were the most common placements for inertial sensors. The three most prevalent biomechanical outcomes studied were: mean spatiotemporal parameters (n = 45), segment or joint angles (n = 33), and linear acceleration magnitudes (n = 22). Our findings demonstrate exceptional growth in this field in the last 5 years. Nevertheless, there remains a need for more longitudinal study designs, patient-specific models, free-living assessments, and a push for "Code Reuse" to maximize the unique capabilities of these devices and ultimately improve how we diagnose and treat this debilitating disease.

Characteristics of three different patellar implant designs in total knee arthroplasty

BACKGROUND

Despite debate over the role of patellar resurfacing in total knee arthroplasty, many surgeons feel it decreases re-operation rates and anterior pain, and an increasing number are adopting resurfacing. This study compares intra-operative characteristics of different patellar implants to assist surgeons in gaining better understanding of these implants.

METHODS

The three most commonly used patellar implants (inset, onlay round and onlay oval) were allocated randomly to 120 patients undergoing total knee arthroplasty. We compared the groups in terms of implant size, bone coverage, lateral underhang (uncovered lateral facet) and need for partial lateral facetectomy. We also compared the patient-reported outcome measures between the groups at 6 months post-operatively.

RESULTS

The inset, onlay round and onlay oval designs had bone coverage of 48.5%, 65.9% and 85.9%, respectively (P < 0.01). Similarly, the onlay-oval implant was found to have the smallest lateral underhang of all three designs (inset 11.6 mm; onlay round 6.9 mm, onlay oval 1.6 mm, P < 0.01). The onlay-oval design was the largest implant with a median size of 35 mm, compared to 23 mm for the inset and 32 mm for the onlay round (P < 0.01). In addition, patellae using onlay-oval implants required significantly fewer lateral facetectomies due to improved bone coverage (inset 95%; onlay round 87%; onlay oval 3%; P < 0.01). Finally, comparison of patient-reported outcome measures between the groups showed no difference at an early assessment of 6 months.

CONCLUSION

Onlay-oval design allows for the use of a larger implant, improving bone coverage and reducing the need for partial lateral facetectomy; however, early assessment of outcomes shows no difference between the three designs.

Current clinical utilisation of wearable motion sensors for the assessment of outcome following knee arthroplasty: a scoping review

OBJECTIVES

Wearable motion sensors are used with increasing frequency in the evaluation of gait, function and physical activity within orthopaedics and sports medicine. The integration of wearable technology into the clinical pathway offers the ability to improve post-operative patient assessment beyond the scope of current, questionnaire-based patient-reported outcome measures. This scoping review assesses the current methodology and clinical application of accelerometers and inertial measurement units for the evaluation of patient activity and functional recovery following knee arthroplasty.

DESIGN

This is a systematically conducted scoping review following Joanna Briggs Institute methodology for scoping reviews and reported consulting the Preferred Reporting Items for Systematic Review and Meta-Analyses extension for scoping reviews. A protocol for this review is registered with the Open Science Framework (https://osf.io/rzg9q).

DATA SOURCES

CINAHL, EMBASE, MEDLINE and Web of Science databases were searched for manuscripts published between 2008 and 2019.

ELIGIBILITY CRITERIA

We included clinical studies reporting the use of any combination of accelerometers, pedometers or inertial measurement units for patient assessment at any time point following knee arthroplasty.

DATA EXTRACTION AND SYNTHESIS

Data extracted from manuscripts included patient demographics, sensor technology, testing protocol and sensor-based outcome variables.

RESULTS

45 studies were identified, including 2076 knee arthroplasty patients, 620 patients with end-stage osteoarthritis and 449 healthy controls. Primary aims of the identified studies included functional assessment, physical activity monitoring and evaluation of knee instability. Methodology varied widely between studies, with inconsistency in reported sensor configuration, testing protocol and output variables.

CONCLUSIONS

The use of wearable sensors in evaluation of knee arthroplasty procedures is becoming increasingly common and offers the potential to improve clinical understanding of recovery and rehabilitation. While current studies lack consistency, significant opportunity exists for the development of standardised measures and protocols for function and physical activity evaluation.

Better outcomes with patellar resurfacing during primary total knee arthroplasty: a meta-analysis study

BACKGROUND

Total knee arthroplasty (TKA) is a feasible and cost-effective procedure. However, resurfacing of the patella sparks a heated debate. Anterior knee pain after TKA was supposed to be correlated to the patellofemoral joint, and the resurface of the patella was believed to be effective to avoid this complication.

AIM

A meta-analysis was performed to update current evidence concerning the outcomes of patellar resurfacing versus retaining for total knee arthroplasty. The first outcomes of interest were to compare the rate of anterior knee pain and revision surgeries.

MATERIAL AND METHODS

This study was conducted according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA). A comprehensive review of the literature was conducted accessing the main databases: Embase, Google Scholar, PubMed, Scopus. All the prospective clinical trials comparing the outcomes between patellar resurfacing versus retaining were included in this study. Only articles classified as level of evidence I to II were considered for inclusion. Only studies reporting a minimum 24 months follow-up were included. The following data were extracted: demographic baseline, anterior knee pain, reoperations, clinical scores (HSS, KSS and related subscales) and range of motion (ROM). Studies solely reporting quantitative data under the outcomes of interest were included.

RESULTS

In favor of the resurfacing group, we observed a statistically significant reduced rate of anterior knee pain (odd ratio 1.73) and reoperation (odd ratio 3.24). In the resurfacing group, a prevalence of anterior knee pain of 11.15% was detected, whereas in the retaining group it amounted to 17.39%. Furthermore, a greater KSS pain (+ 0.97%), KSS clinical (+ 0.23%), KSS functional (+ 2.44%), KSS overall (+ 2.47%) and HSS (+ 5.64%) were reported. In the retaining group, we found a better range of motion (+ 3.09°).

CONCLUSION

Based on the main findings of this meta-analysis, patellar resurfaced TKA was demonstrated to have performed superior overall. Patellar resurfacing detected a lower rate of postoperative anterior knee pain and reoperation. Moreover, the resurfacing group showed greater value of the HSS, KSS and related subscales. In favor of the retaining group, a slightly better ROM was evidenced.

LEVEL OF EVIDENCE

Level II, meta-analysis of prospective clinical trials.

Patellar Resurfacing in Total Knee Arthroplasty: Systematic Review and Meta-Analysis

BACKGROUND

Patellar resurfacing in total knee arthroplasty remains controversial. The aim of this study is to evaluate this technique through an analysis of comparative studies in the current literature.

METHODS

We performed a comprehensive search of PubMed, MEDLINE, Cochrane, CINAHL, and EMBASE databases using various combinations of the keywords "Knee," "Replacement," "Prosthesis," "Patella," "Resurfacing," and "Arthroplasty." All articles relevant to the subject were retrieved, and their bibliographies were hand searched for further references relevant to primary patellar resurfacing in total knee arthroplasty. Only articles published in peer-reviewed journals were included in this systematic review.

RESULTS

The percentage for a reoperation was 1% for the patellar resurfacing group (17/1636) and 6.9% for the non-resurfacing group (118/1699) (odds ratio [OR] 0.18, 95% confidence interval [CI] 0.11-0.29, P < .00001). The patellar resurfacing group showed a significantly higher postop Knee Society Score (KSS) pain (OR 1.52, 95% CI 0.68-2.35, P = .004) and postop Hospital for Special Surgery score (OR 4.35, 95% CI 3.21-5.49, P < .00001), over the non-resurfacing group.

CONCLUSION

Based on the outcome scores of KSS (pain), KSS (function), and Hospital for Special Surgery postop, patellar resurfacing TKAs have performed better than non-resurfaced TKAs. The lower secondary operation and revision rates for patellar resurfaced TKAs also demonstrate that this technique is the more effective option. However, the full impact of patellar resurfacing still needs to be critically evaluated by larger randomized controlled trials with long-term follow-up.

Patellar resurfacing in total knee arthroplasty: functional outcome differs with different outcome scores: A randomized, double-blind study of 129 knees with 3 years of follow-up

BACKGROUND AND PURPOSE

Recent research on outcomes after total knee arthroplasty (TKA) has raised the question of the ability of traditional outcome measures to distinguish between treatments. We compared functional outcomes in patients undergoing TKA with and without patellar resurfacing, using the knee injury and osteoarthritis outcome score (KOOS) as the primary outcome and 3 traditional outcome measures as secondary outcomes.

PATIENTS AND METHODS

129 knees in 115 patients (mean age 70 (42-82) years; 67 female) were evaluated in this single-center, randomized, double-blind study. Data were recorded preoperatively, at 1 year, and at 3 years, and were assessed using repeated-measures mixed models.

RESULTS

The mean subscores for the KOOS after surgery were statistically significantly in favor of patellar resurfacing: sport/recreation, knee-related quality of life, pain, and symptoms. No statistically significant differences between the groups were observed with the Knee Society clinical rating system, with the Oxford knee score, and with visual analog scale (VAS) for patient satisfaction.

INTERPRETATION

In the present study, the KOOS--but no other outcome measure used--indicated that patellar resurfacing may be beneficial in TKA.

Validation of the German Forgotten Joint Score (G-FJS) according to the COSMIN checklist: does a reduction in joint awareness indicate clinical improvement after arthroplasty of the knee?

PURPOSE

Evaluation of further improvement in treatment of patients with osteoarthritis of the knee requires measurement tools with a high discriminatory power. In this context, joint awareness in everyday life is seen as crucial criterion. Purpose of this study was to adapt and validate a German version of the "Forgotten Joint Score" (FJS) according to the COSMIN checklist.

METHODS

We evaluated a German translation of the FJS for reliability, validity and responsiveness according to the COSMIN checklist. Therefore, patients with an artificial knee joint completed the G-FJS questionnaire twice at intervals of at least 2 weeks. In addition, the Knee Society Score, the Oxford Knee Score, the Tegner Activity Scale, a Visual Analogue Scale, the EuroQol-5D (EQ 5-D), and a subjective assessment of the limitations were recorded.

RESULTS

Between June and December 2014, one hundred and five patients (average age 65.2 years) completed both questionnaires and were available for data analysis. Test-retest reliability of the FJS was high with an ICC = 0.80 (95 % CI 0.69, 0.90) and with a Cronbach's alpha of 0.95 (95 % CI 0.92, 0.99).

CONCLUSIONS

The German translation of the FJS is a viable tool for the postoperative monitoring after arthroplasty of the knee. This is the first study providing data on test-retest reliability of the FJS. The FJS is a reliable and valid measurement tool for evaluation of patient rated outcome in patients with an artificial knee joint.

LEVEL OF EVIDENCE

Validating cohort study, Level 1b.

The assessment of outcome after total knee arthroplasty: are we there yet?

The routine use of patient reported outcome measures (PROMs) in evaluating the outcome after arthroplasty by healthcare organisations reflects a growing recognition of the importance of patients' perspectives in improving treatment. Although widely embraced in the NHS, there are concerns that PROMs are being used beyond their means due to a poor understanding of their limitations. This paper reviews some of the current challenges in using PROMs to evaluate total knee arthroplasty. It highlights alternative methods that have been used to improve the assessment of outcome.

Knee arthroplasty with a medial rotating total knee replacement. Midterm clinical findings: a district general experience of 38 cases

BACKGROUND

The Medial Rotating Knee replacement (MRK) was first used in 1994, reporting high rates of satisfaction. It is designed to replicate natural knee kinematics and improve stability and function. There are limited studies on the mid-term clinical outcomes, in particular in a district general hospital (DGH) environment. This is the first study that we are aware of that evaluates the learning curve of the implementation of this knee system in this environment.

PATIENTS/METHOD

Between 2007 and 2009 we performed 38 consecutive MRK replacements (MAT ORTHO, UK) in 36 patients. The mean follow-up was four years. Patients were evaluated clinically, using OKS and patient questionnaire and radiographically (good/acceptable/poor) to assess outcome.

RESULTS

Mean age was 73.0 years. Mean pre-operative OKS was 17.7 (range 8-29), which rose to 38.1 (range 23-48) at latest follow up (p<0.005). Overall 71% of the patients were either satisfied (29%) or very satisfied (42%). 81% felt an improvement of the ability to go up or down stairs and 92% felt stable. All poor radiographic and the majority of acceptable outcomes were experienced in the first 50% of cases.

CONCLUSION

The MRK can be successfully implanted in a DGH environment. It improves pain and function comparably to standard TKRs, however, subjective improvement may be higher. Radiographic evaluation shows an acceptable learning curve.

LEVEL OF EVIDENCE

Level IV case series.

Patellar denervation with electrocautery in total knee arthroplasty without patellar resurfacing: a meta-analysis

PURPOSE

The impact of patellar denervation with electrocautery in total knee arthroplasty (TKA) on post-operative outcomes has been under debate. This study aims to conduct a meta-analysis and systematic review to compare the benefits and risks of circumpatellar electrocautery with those of non-electrocautery in primary TKAs.

METHODS

Comparative and randomized clinical studies were identified by conducting an electronic search of articles dated up to September 2012 in PubMed, EMBASE, Scopus, and the Cochrane databases. Six studies that focus on a total of 849 knees were analysed. A random-effects model was conducted using the inverse-variance method for continuous variables and the Mantel-Haenszel method for dichotomous variables.

RESULTS

There was no significant difference in the incidence of anterior knee pain between the electrocautery and non-electrocautery groups. In term of patellar score and Knee Society Score, circumpatellar electrocautery improved clinical outcomes compared with non-electrocautery in TKAs. The statistical differences were in favour of the electrocautery group but have minimal clinical significance. In addition, the overall complications indicate no statistical significance between the two groups.

CONCLUSIONS

This study shows no strong evidence either for or against electrocautery compared with non-electrocautery in TKAs.

LEVEL OF EVIDENCE

Therapeutic study (systematic review and meta-analysis), Level III.

Early PROMs following total knee arthroplasty--functional outcome dependent on patella resurfacing

Patella resurfacing during primary total knee arthroplasty (TKA) remains controversial. Variation in published results for patella resurfacing may potentially be explained by differences in design between TKA brands. We interrogated NJR-PROMs data to ascertain whether there is an early functional benefit to resurfacing the patella, both overall and for each of the five most popular primary knee designs through use of the Oxford Knee Score. A total of 8103 resurfaced TKAs and 15,290 nonresurfaced TKAs were studied. There was a large variation in the proportion of knees undergoing patella resurfacing by brand (Nexgen=16% versus Triathlon=52%). Patellar resurfacing did not significantly influence the magnitude of improvement in overall knee function or anterior knee-specific function irrespective of TKA brand or for cruciate retaining versus sacrificing designs.

A performance based patient outcome score for active patients following total knee arthroplasty

OBJECTIVE

The aim of this study was to develop and validate a user friendly performance based knee outcome score for use in active patients undergoing TKA surgery.

DESIGN

We prospectively studied a cohort of 50 subjects without any knee symptoms, and 50 patients who underwent TKA for osteoarthritis (OA). The patients were assessed pre- and postoperatively. SF-36 and WOMAC were concurrently administered for comparison. Patients completed seven physical tasks of the finalised outcome instrument which were objectively assessed and scored.

RESULTS

The mean functional score was 31.7 in the normal subjects. The mean functional score improved postoperatively from 10.0 to 17.7 (P < 0.001) in the TKA group. Our results confirm that the performance based score has a high test-retest reliability (intra-class correlation coefficient (ICC) of 0.89), internal consistency (Cronbach's alpha 0.84) and construct validity showing expected correlations with relevant components of the WOMAC and SF-36 scores. The responsiveness as measured by the effect size compared favourably with the same relevant components of the SF-36 and WOMAC.

CONCLUSIONS

Our performance based knee function score is a reliable dimension specific tool to detect change in musculoskeletal function after TKA. It complements existing self-reported outcome tools in facilitating a comprehensive assessment of patients following TKA.

Patellar denervation in total knee arthroplasty without patellar resurfacing: a prospective, randomized controlled study

BACKGROUND

Anterior knee pain is still a major problem in total knee arthroplasty (TKA). Although the most widely accepted opinion is that anterior knee pain is often associated with a patellofemoral etiology, there is no clear consensus as to etiology or treatment. Disabling pain receptors by electrocautery could theoretically achieve denervation of the anterior knee region. The present prospective randomized controlled study aimed to evaluate results after patellar denervation with electrocautery in TKA at a minimum follow-up of 2 years.

HYPOTHESIS

Patellar denervation provides some benefit in terms of pain and clinical outcomes after TKA without patellar resurfacing.

PATIENTS AND METHODS

Clinical and radiological results for 35 patients with single-stage bilateral TKA (70 knees; 26 women, nine men; mean age, 68 years [range, 58 to 77 years]) were reviewed. In addition to removal of all osteophytes, patellar denervation by electrocautery was performed on one patella; and debridement alone, removing all osteophytes, was performed on the contralateral patella, as a control. KSS score and a visual analog scale (VAS) were used to assess pre- and postoperative anterior knee pain.

RESULTS

Mean follow-up was 36 months (24 to 60 months). No revisions or re-operations were performed. There were no patellar fractures. On all parameters (KSS score, range of motion and VAS), there was a statistically significant pre- to postoperative difference in favor of the denervation group.

DISCUSSION

Patellar denervation with electrocautery can reduce anterior knee pain, with satisfactory clinical and radiological outcome, in TKA without patellar resurfacing.

LEVEL OF EVIDENCE

Level II: low-powered prospective randomized trial.

A randomised, controlled trial of circumpatellar electrocautery in total knee replacement without patellar resurfacing

The efficacy of circumpatellar electrocautery in reducing the incidence of post-operative anterior knee pain is unknown. We conducted a single-centre, outcome-assessor and patient-blinded, parallel-group, randomised, controlled trial to compare circumpatellar electrocautery with no electrocautery in total knee replacement in the absence of patellar resurfacing. Patients requiring knee replacement for primary osteoarthritis were randomly assigned circumpatellar electrocautery (intervention group) or no electrocautery (control group). The primary outcome measure was the incidence of anterior knee pain. A secondary measure was the standardised clinical and patient-reported outcomes determined by the American Knee Society scores and the Western Ontario and McMaster Universities (WOMAC) osteoarthritis index. A total of 131 knees received circumpatellar electrocautery and 131 had no electrocautery. The overall incidence of anterior knee pain at follow-up at one year was 26% (20% to 31%), with 19% (12% to 26%) in the intervention group and 32% (24% to 40%) in the control group (p = 0.02). The relative risk reduction from electrocautery was 40% (9% to 61%) and the number needed to treat was 7.7 (4.3 to 41.4). The intervention group had a better mean total WOMAC score at follow-up at one year compared with the control group (16.3 (0 to 77.7) versus 21.6 (0 to 76.7), p = 0.04). The mean post-operative American Knee Society knee scores and function scores were similar in the intervention and control groups (knee score: 92.4 (55 to 100) versus 90.4 (51 to 100), respectively (p = 0.14); function score: 86.5 (15 to 100) versus 84.5 (30 to 100), respectively (p = 0.49)). Our study suggests that in the absence of patellar resurfacing electrocautery around the margin of the patella improves the outcome of total knee replacement.

Early functional outcome after subvastus or parapatellar approach in knee arthroplasty is comparable

PURPOSE

In total knee arthroplasty, tissue-sparing techniques are considered more important, as functional gain could become more advantageous when early mobilization is commenced. The parapatellar approach is most often used, whereas the subvastus approach is a suitable alternative. Presently, it is unknown, according to true objective measurements, which of the two is most advantageous.

METHODS

In this prospective randomized double-blind, short-term trial measurements (KSS, WOMAC, PDI, VAS, ability to perform) were obtained at day 1, day 3, 1 week, 6 weeks, and 3 months.

RESULTS

The subvastus group (n=20) showed only significantly less extension lag direct postoperative (P=0.04) compared with the parapatellar group (n=20). Other scores were not significantly different. The Dynaport®knee test, an objective performance-based tool, could not demonstrate significant differences. A blunt anatomical dissection was carried out in both observational and histological to support findings. A dense innervation of the distal vastus medialis was found. This is at risk employing the subvastus approach. Both approaches harm the suprapatellar bursa. The vastus medialis sheath must be detached distally to open the knee joint. No true separate vastus medialis obliquus could be identified.

CONCLUSION

Comparable to literature, only mild advantage employing the subvastus approach was found, but only early postoperative and not objectively. As this approach is also not suitable in every case, we will continue to use the parapatellar approach.

A dutch survey on circumpatellar electrocautery in total knee arthroplasty

Introduction:

Anterior knee pain following total knee arthroplasty is estimated to occur in 4-49% of patients. Some orthopedic surgeons use circumpatellar electrocautery (diathermy) to reduce the prevalence of postsurgical anterior knee pain; however, the extent of its use is unknown.

Materials and Methodology:

In April 2009, a postal questionnaire was sent to all 98 departments of orthopedic surgery in The Netherlands. The questions focused on the frequency of total knee arthroplasties, patellar resurfacing, and the use of circumpatellar electrocautery.

Results:

The response rate was 92%. A total of 18,876 TKAs, 2,096 unicompartmental knee arthroplasties, and 215 patellofemoral arthroplasties are performed yearly in The Netherlands by the responding orthopedic surgeons. Of the orthopedic surgeons performing TKA, 13% always use patellar resurfacing in total knee arthroplasty for osteoarthritis, 49% use selective patellar resurfacing, and 38% never use it. Fifty-six percent of orthopedic surgeons use circumpatellar electrocautery when not resurfacing the patella, and 32% use electrocautery when resurfacing the patella.

Conclusion:

There is no consensus among Dutch orthopedic surgeons on the use of patellar resurfacing or circumpatellar electrocautery in total knee replacement performed for osteoarthritis. A prospective clinical trial is currently underway to fully evaluate the effect of circumpatellar electrocautery on the prevalence of anterior knee pain following total knee arthroplasty.

Early outcomes of patella resurfacing in total knee arthroplasty

BACKGROUND

Patella resurfacing in total knee arthroplasty is a contentious issue. The literature suggests that resurfacing of the patella is based on surgeon preference, and little is known about the role and timing of resurfacing and how this affects outcomes.

METHODS

We analyzed 134,799 total knee arthroplasties using data from the Australian Orthopaedic Association National Joint Replacement Registry. Hazards ratios (HRs) were used to compare rates of early revision between patella resurfacing at the primary procedure (the resurfacing group, R) and primary arthroplasty without resurfacing (no-resurfacing group, NR). We also analyzed the outcomes of NR that were revised for isolated patella addition.

RESULTS

At 5 years, the R group showed a lower revision rate than the NR group: cumulative per cent revision (CPR) 3.1% and 4.0%, respectively (HR = 0.75, p < 0.001). Revisions for patellofemoral pain were more common in the NR group (17%) than in the R group (1%), and "patella only" revisions were more common in the NR group (29%) than in the R group (6%). Non-resurfaced knees revised for isolated patella addition had a higher revision rate than patella resurfacing at the primary procedure, with a 4-year CPR of 15% and 2.8%, respectively (HR = 4.1, p < 0.001).

INTERPRETATION

Rates of early revision of primary total knees were higher when the patella was not resurfaced, and suggest that surgeons may be inclined to resurface later if there is patellofemoral pain. However, 15% of non-resurfaced knees revised for patella addition are re-revised by 4 years. Our results suggest an early beneficial outcome for patella resurfacing at primary arthroplasty based on revision rates up to 5 years.