Patellar resurfacing versus patellar retention in primary total knee arthroplasty: a systematic review of overlapping meta-analyses

Purpose

The need of patellar resurfacing in total knee arthroplasty (TKA) is a subject of debate. This systematic review of overlapping meta-analyses aimed to assess and analyze current evidence regarding patellar resurfacing and non-resurfacing in TKA.

Methods

A systematic literature search was performed in March 2017 in PubMed, CINAHL and Cochrane Library. Inclusion criteria were meta-analysis of randomized controlled trials that compared TKA with and without patellar resurfacing considering as outcomes re-operations rate, complications, anterior knee pain, functional scores. The quality of meta-analyses was evaluated with AMSTAR score and the most relevant meta-analysis was determined by applying the Jadad algorithm.

Results

Ten meta-analyses, published between 2005 and 2015, were included in the systematic review. Two studies found a significantly increased Knee Society Score in the resurfacing group. According to four meta-analyses, anterior knee pain incidence was lower in resurfacing group. Six of the included studies described a greater risk of re-intervention in the non-resurfacing groups. The overall quality of included studies was moderate. The most relevant meta-analysis reported no differences in functional scores and incidence of anterior knee pain between the groups.

Conclusions

Comparable outcomes were found when comparing patellar resurfacing and non-resurfacing in TKA. The higher risk of re-operations after non-resurfacing should be interpreted with caution due to the methodological limitations of the meta-analyses regarding search criteria, heterogeneity and the inherent bias of easier indication to reoperation when the patella is not resurfaced. There is no clear superiority of patellar resurfacing compared to patellar retention.

Level of evidence

Level II, systematic review of meta-analyses.

     

Secondary patellar resurfacing in the treatment of patellofemoral pain after total knee arthroplasty

Purpose  

This paper reports a prospective review of patients who, between 2004 and 2007, underwent secondary patellar resurfacing (SPR) due to anterior knee pain after a primary total knee arthroplasty (TKA). The aim was to evaluate the clinical outcomes obtained with the SPR and to compare them with radiological findings.     

Tibio-femoral and patello-femoral joint kinematics during navigated total knee arthroplasty with patellar resurfacing

Purpose

In total knee arthroplasty, surgical navigation systems provide tibio-femoral joint (TFJ) tracking for relevant bone preparation, disregarding the patello-femoral joint (PFJ). Therefore, the important intra-operative assessment of the effect of component positioning, including the patella, on the kinematics of these two joints is not available. The objective of this study is to explore in vivo whether accurate tracking of the patella can result in a more physiological TFJ and PFJ kinematics during surgery.

Methods

Ten patients underwent navigated knee replacement with patellar resurfacing. A secondary system was used to track patellar motion and PFJ kinematics using a special tracker. Patellar resection plane position and orientation were recorded using an instrumented probe. During all surgical steps, PFJ kinematics was measured in addition to TFJ kinematics.

Results

Abnormal PFJ motion patterns were observed pre-operatively at the impaired knee. Patellar resection plane orientation on sagittal and transverse planes of 3.9° ± 9.0° and 0.4° ± 4.1° was found. A good restoration of both TFJ and PFJ kinematics was observed in all replaced knees after resurfacing, in particular the rotations in the three anatomical planes and medio-lateral patellar translation.

Conclusions

Patella tracking results in nearly physiological TFJ and PFJ kinematics in navigated knee arthroplasty with resurfacing. The intra-operative availability also of PFJ kinematics can support the positioning not only of the patellar component in case of resurfacing, but also of femoral and tibial components.

Level of evidence

II.     

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.     

No differences between fixed- and mobile-bearing total knee arthroplasty

Purpose

For years, numerous studies have been performed to determine whether mobile-bearing total knee arthroplasty (MB-TKA) or fixed-bearing total knee arthroplasty (FB-TKA) is the preferential design in total knee arthroplasty. Reviews and meta-analyses on this subject have focused on a relatively small number of randomised controlled trials, possibly missing important results of smaller studies. The goal of this review was to provide a comprehensive overview of all literature comparing MB-TKA and FB-TKA in the treatment of osteoarthritis of the knee.

Methods

An extensive literature search was performed in the PubMed database. All studies that compared MB-TKA with FB-TKA and looked at one of four theorised advantages (insert wear, signs of loosening, survival rate of the prosthesis and clinical outcome) were included.

Results

The initial search yielded 258 articles, of which 127 were included after the first screening. The included studies consisted of 9 meta-analyses, 3 systematic reviews, 48 RCT’s, 44 comparative studies, 10 reviews and 13 studies that examined patients who received bilateral TKA (one MB-TKA and one FB-TKA). Combining the results of all studies showed that almost all studies found no difference between MB-TKA and FB-TKA.

Conclusions

Even when examining all different types of studies on MB-TKA and FB-TKA, the results of this review showed no difference in insert wear, risk of loosening, survivorship or clinical outcome. In daily practice, the choice between MB-TKA and FB-TKA should be based on the experience and judgment of the surgeon, since no clear differences are observed in the scientific literature.

Level of evidence

III.

     

Total knee arthroplasty without patellar resurfacing in active and overweight patients

Overweight patients are often considered poor candidates for total knee arthroplasty (TKA). A retrospective study of this was done on 47 osteoarthritic knees treated by TKA without patella resurfacing between March 1991 and June 1993. The Hospital for Special Surgery (HSS) rating system was used for clinical evaluation, and radiographs to study the degree of osteoarthritis and radiolucency. Correlations between overweight, range of motion (ROM) and stage of patellar damage and other measured variables (HSS score, patellar pain and radiolucency) were studied. Overweight was not correlated with HSS score, radiolucency or patellar pain. ROM was significantly correlated with patellar pain and HSS score, with better results in patients with ROM between 90° and 110°. Therefore, we believe that TKA in osteoarthritic knees can lead to successful results, even in active or overweight patients. Received: 19 November 1996 Accepted: 7 April 1997     

Changes in patellar alignment after total knee arthroplasty

Although the results of total knee arthroplasty continue to improve, problems related to the patellofemoral joint remain significant. This study examined the factors affecting patellar alignment after total knee arthroplasty and subsequent changes in 56 knees during a postoperative period of 5.3 years. None of the knees examined displayed any clinical complications of the patellofemoral joint; no revision surgeries were necessary, with acceptable patellar alignment on average. The patellar resection angle had a strong influence on patellar alignment. Thinning of the patellar remnant on the medial side can increase postoperative lateral tilt, which leads to a need for lateral retinacular release. Although the changes in patellar alignment were minimal, the tendency that postoperative varus alignment resulted in patellar lateral tilt was observed. As postoperative femorotibial misalignment can lead to patellofemoral problems after total knee arthroplasty, surgeons need to pay scrupulous attention to femorotibial alignment and proper patellar preparation to decrease patellofemoral complications.     

Patellar morphology and femoral component geometry influence patellofemoral contact stress in total knee arthroplasty without patellar resurfacing

Purpose

The objective of this study was to determine the effect of patellar morphology and implant design on patellofemoral contact stress in total knee arthroplasty (TKA) without patellar resurfacing.

Methods

Radiographic investigation: One hundred and fifty-seven knees of 127 patients were included in the study. Implants used in the present series were Low Contact Stress (LCS), Genesis II and NexGen. The relationship between the pre-operative patellar facet angle and newly identified post-operative osteosclerosis was assessed. Finite element analysis: Using patient-specific patellar three-dimensional finite element models, the relationship between the patellar facet angle and mean von Mises stress within the patella was calculated at flexion angles of 15°, 45°, 75° and 105°.

Results

Radiographic investigation: Post-operative osteosclerosis was observed with decreasing patellar facet angle in the Genesis II (odds ratio?=?0.72; 95% confidence interval, 0.55–0.93; P?=?0.012) and NexGen implants (odds ratio?=?0.87; 95% confidence interval, 0.77–0.99; P?=?0.029). Patients treated with the Genesis II had significantly more advanced osteosclerosis than those treated with the other two implants. Finite element analysis: A negative correlation was found between the patellar facet angle and the mean von Mises stress for all three implants. The Genesis II showed significantly higher von Mises stress than the other two implants at flexion angles of 15°, 45° and 105°.

Conclusions

Both patellar morphology and femoral component geometry influence patellofemoral contact stress in total knee arthroplasty without patellar resurfacing.

Level of evidence

Case control study, Level III.     

Effect of patellar thickness on early results of total knee replacement with patellar resurfacing

Purpose

Patellar thickness is a concern in total knee replacement with patellar resurfacing because of the risk of patellar fracture or implant loosening. The aim of this study was to evaluate if patellar thickness is related to clinical outcome in the absence of patellar fracture or implant loosening.

Methods

Early results of 169 patients who underwent total knee replacement with patellar resurfacing were reviewed to assess the effect of patellar thickness on clinical outcome. The mean follow-up was 13 months. The range of motion, Knee Society Score, Function Score and WOMAC Score were assessed preoperatively, at day 0, 6 months and 1 year. Radiographs were assessed for patellar fracture or implant loosening.

Results

Thirty-one percent of all patients had preoperative thickness <21 mm. Seven percent had <12 mm residual thickness after patellar cut, all were female. Twenty-three percent had ≥1 mm increase of thickness after surgery. Radiographs did not show any patellar fracture or implant loosening. However, preoperative patellar thickness <21 mm had poorer gain in range of motion at 1 year. Preoperative range of motion had greater influence on postoperative range of motion than preoperative patellar thickness. Residual thickness <12 mm had lower gain in WOMAC score at 1 year and an increase in thickness ≥1 mm postoperatively was associated with lower gain in WOMAC score at 6 months.

Conclusions

Early results of patellar resurfacing with preoperative thickness <21 mm or residual thickness <12 mm were found to be inferior even in the absence of patellar fracture or implant loosening. Conservative cutting resulting in 1 mm increase in thickness was also found to have inferior clinical results.

Level of evidence

II.     

What have we learned from LCS mobile-bearing knee system?

Three hundred and sixty-four low contact stress (LCS) total knee arthroplasties that could be followed up for more than 5 years were clinically and radiographically analyzed. The median postoperative Hospital for Special Surgery score improved from 56 (range 32–77) to 91 (range 64–100) points, but median range of motion did not change from 120° (range 50°–135°) to 120° (range 85°–135°). Complications occurred in 16 cases (4%), and included postoperative polyethylene dislocation and intraoperative tibial condylar fracture, while five knees (1%) required revision surgery due to mechanical reasons. The overall prosthesis survival rate was 91% at 12 years. Although the LCS mobile-bearing knee system has theoretical advantages in terms of wear and loosening, the problem of polyethylene dislocation, intraoperative tibial fracture, and radiolucent lines should be solved for long survival. The clinical relevance of this study is that the LCS system provided good clinical and survival results.     

The effect of patellar thickness changes on patellar tilt in total knee arthroplasty

We hypothesized that changes in patellar thickness following patellar resurfacing affect patellar tilt in total knee arthroplasty (TKA) patients. The study enrolled 272 TKAs and categorized them into four groups according to change in patellar thickness: (A) thinner by 1 mm or more, (B) equal or thinner by less than 1 mm, (C) thicker by 1 mm or less, and (D) thicker by more than 1 mm. Patellar tilt angle was measured postoperatively using Merchant radiography. There were no significant differences in postoperative patellar tilt among groups A, B, and C (n.s). However, the postoperative patellar tilting angle of group D was significantly higher than that of all other groups (P < 0.05). Postoperative patellar tilt increased when the postoperative patella was >1 mm thicker than the preoperative patella.     

An alternative patellar resurfacing technique in knee replacement: patellofemoral fascial interposition arthroplasty

The present study reports the early clinical results of 38 osteoarthritic patients (38 knees) who were treated by total knee replacement in conjunction with patellofemoral fascial interposition arthroplasty (PFIA). After the femoral and tibial components were inserted, a fasciotendinous graft was harvested from the anterior surface of the quadriceps tendon and sutured around the articular surface of the patella. The patients were followed-up for a minimum of 24 months. The durability of the fascial graft was assessed radiographically by addition of a wire suture marker placed into the fascia in the first five patients. Patients were evaluated using the Hospital for Special Surgery (HSS) knee-rating system, and anterior knee pain was assessed using specific patellofemoral-related questions. The average HSS knee score improved from 61 points preoperatively to 92 points at 24 months' follow-up (P<0.001). Twenty-five patients (65.7%) had anterior knee pain preoperatively, and seven patients (18.4%) revealed anterior knee pain at their last visits (P<0.001). The position of the markers in the fascial grafts did not show any change during radiological follow-ups. Our data suggest that, PFIA provides good pain relief and it may be an alternative resurfacing technique avoiding the complications of patellar components.     

Less anterior knee pain with a routine lateral release in total knee arthroplasty without patellar resurfacing: a prospective,randomized study

Purpose

Anterior knee pain is a major cause of complaint in total knee arthroplasty (TKA) without patellar resurfacing. The concept of improved patellar tracking and decreased retropatellar contact pressure for lateral retinacular release theoretically suggests that patients with lateral retinacular release in TKA would achieve a lower incidence of anterior knee pain when compared without lateral retinacular release. We sought to determine (1) whether those patients who received a routine lateral retinacular release in TKA would attain lower incidence of anterior knee pain as compared to patients who received TKA without lateral retinacular release and (2) whether lateral retinacular release would increase the lateral retinacular release-related complications.

Methods

A total of 148 patients who underwent TKA with the use of the Gemini MK II mobile bearing were randomized to receive either routine lateral retinacular release (intervention group) or not (control group). Patients were assessed by the visual analogue scale for anterior knee pain, the Knee Society clinical scoring system of knee score and function score, and patellar score for clinical function. Patients’ satisfaction and lateral retinacular release-related complications were also evaluated.

Results

The overall incidence of anterior knee pain in the intervention group at 18 months follow-up was 5.6 %, while that of the control group was 20.6 % (p = 0.009). No statistical difference was detected between the two groups in terms of lateral retinacular release-related complications (n.s.), patients’ satisfaction (n.s.), knee score (n.s.), function score (n.s.), and patellar score (n.s.) at 18 months follow-up.

Conclusion

The present study suggests that routine lateral retinacular release can reduce anterior knee pain and does not increase lateral retinacular release-related complications, in TKA with the use of the Gemini MK II mobile bearing without patellar resurfacing.

Level of evidence

Therapeutic, Level I.     

Balancing mobile-bearing unicondylar knee arthroplasty in vitro

Purpose

Balancing mobile-bearing (MB) unicondylar knee arthroplasty (UKA) is challenging. If performed improperly, potential complications include pain, implant loosening, or progression of osteoarthritis in the preserved compartment. The purpose of this study was to document effects of improper balancing on knee kinematics and joint contact stress. It was hypothesized that over-stuffing would lead to more valgus and higher lateral contact force.

Methods

Seven fresh-frozen cadaver legs were mounted in a kinematic rig that applied three motion patterns to the specimens: passive flexion–extension, open chain extension, and squatting. During testing, an infrared camera system recorded the trajectories of markers rigidly attached to femur and tibia, while a pressure sensor measured contact pressure in the lateral compartment. Prior computer tomography scans allowed identification of coordinate frames of the bones and calculations of anatomical rotations and translations. Collateral ligament strains were calculated, and quadriceps forces recorded. Following testing on the native knee, a medial MB UKA was implanted in each specimen and all motion trials were repeated. Three inlay thicknesses were tested to simulate optimal balancing as well as under- (1 mm thinner) and over-stuffing (1 mm thicker) of the medial compartment relative to the optimal thickness.

Results

Under-stuffing of the medial compartment leads to kinematics closest to the native knee. Subjectively balanced and over-stuffed MB UKA knees were in more valgus. Lateral peak contact stress was higher from mid- to deep flexion following UKA in all three tested states; however, these results were not significant. Peak strain in the superficial medial collateral ligament (sMCL) was significantly higher in MB UKA, regardless of the inlay thickness mainly in mid-flexion. Inlay thickness had no significant impact on measured quadriceps force during squatting.

Conclusion

The results underline the importance of optimal balancing. Over-stuffing should be avoided as it results in the largest kinematic changes relative to the native condition and induces higher strains in the sMCL. Based on the kinematic findings, it is advisable to use thinner inlays, as long as this is not compromising stability or risking inlay luxation.

     

Patellar resurfacing in total knee arthroplasty for osteoarthritis: a meta-analysis

Purpose  

Whether to resurface the patella during a primary total knee arthroplasty remains a controversial issue. The aim of this study was to determine the advantages and disadvantages of patellar resurfacing during total knee arthroplasty for osteoarthritis through an evaluation of the current literature.     

In vivo kinematics of mobile-bearing total knee arthroplasty during deep knee bending under weight-bearing conditions

Purpose  

Little is known about the in vivo kinematics of mobile-bearing total knee arthroplasty, especially at deep knee flexion under weight-bearing conditions.