Comparison of two total knee prostheses on the incidence of patella clunk syndrome

Comparison of clinical outcomes between patellar resurfacing and patellar non-resurfacing in cruciate retaining total knee arthroplasty

BACKGROUND

It is not established whether patellar resurfacing is better than patellar non-resurfacing during total knee arthroplasty (TKA). This study was to compare the clinical outcomes between groups with patellar resurfacing and non-resurfacing during cruciate retaining (CR) TKA.

METHODS

In this retrospective cohort study, subjects undergoing primary CR TKA for osteoarthritis between 2012 and 2019 were included. Of 500 subjects, 250 had patellar resurfacing (group 1) and 250 had patellar non-resurfacing (group 2) CR TKA. Knee society knee score (KSKS), knee society function score (KSFS), Western Ontario and McMaster Universities Osteoarthritis (WOMAC) scale, Kujala score, anterior knee pain, patellar compression test and range of motion (ROM) of the replaced knee were assessed and compared between the two groups.

RESULTS

There were no significant differences in KSKS, KSFS, WOMAC scale, Kujala score, prevalence of anterior knee pain and ROM of the replaced knee between the two groups at the last follow-up (p > .05). Group 2 had more subjects with positive patellar compression test than group 1 at the last follow-up (p = .010).

CONCLUSIONS

Clinical and functional outcomes of the replaced knee were not different between patellar resurfacing and non-resurfacing groups. Anterior knee pain was significantly reduced after total knee arthroplasty regardless of patellar resurfacing.

LEVEL OF EVIDENCE

Retrospective cohort study, Level III.

No difference between resurfaced and non-resurfaced patellae with a modern prosthesis design: a prospective randomized study of 250 total knee arthroplasties

PURPOSE

Despite numerous well-conducted studies and meta-analyses, the management of the patella during total knee arthroplasty (TKA) remains controversial. The aim of our study was to compare the clinical and radiological outcomes between patients with and without patellar resurfacing and to determine the influence of resurfacing on patellar tracking with a "patella-friendly" prosthesis.

METHODS

A single-centered prospective randomized controlled study was performed between April 2017 and November 2018. Two hundred and forty-five consecutive patients (250 knees) scheduled for TKA were randomized for patellar resurfacing or patella non-resurfacing. All patients received the same total knee prosthesis and were evaluated clinically and radiologically, including the International Knee Society Score (KSS knee and function), Forgotten Joint Score (FJS), anterior knee pain (AKP), pain when climbing stairs, patellar tilt, and patellar translation.

RESULTS

Two hundred and twenty-nine knees were available for clinical evaluation and 221 knees for radiographic analysis. The revision rate for patellofemoral cause was 3.1% (7 cases) with no difference between the groups (p = 0.217). There was no difference in survival rate between patellar resurfacing (88.3%) and non-resurfacing (85.3%) after 24 months (p = 0.599). There were no differences in KSS functional component (p = 0.599), KSS knee component (p = 0.396), FJS (p = 0.798), and AKP (p = 0.688) at a mean follow-up of 18 months. There was twice as much stair pain for the non-resurfacing group (17.1% versus 8.5%) (p = 0.043). There was patellar tilt in 43% of resurfaced knees (n = 50/116) versus 29% in non-resurfaced knees (n = 30/105) (p = 0.025); however, there was more patellar translation in the non-resurfaced group (21.0% versus 7.8%) (p < 0.001). There were no specific complications attributed to the patellar resurfacing procedure. There were four secondary patellar resurfacing procedures (3.6%) in the non-resurfaced group after a mean of 10 ± 7 months (1-17) postoperatively.

CONCLUSION

There is no superiority of patellar resurfacing or non-resurfacing in terms of clinical or radiological outcomes at mid-term. Secondary patellar resurfacing is rare. There is not enough evidence to recommend systematic patellar resurfacing with a "patella-friendly" prosthesis.

Onlay Patellar Resurfacing in a Posterior-Stabilized Total Knee Arthroplasty Increases Patellar Crepitus Complication: A Randomized, Controlled Trial

BACKGROUND

Patellar crepitus (PC) is a potentially problematic complication after total knee arthroplasty (TKA) more commonly occurring with a posterior-stabilized (PS) prosthesis. Patellar resurfacing has been reported to reduce PC complications; however, no study has compared the PC complication rates between 2 different resurfacing techniques, namely inlay and onlay.

METHODS

A prospective, randomized controlled trial was conducted to compare the PC complication between inlay and onlay patellar resurfacing techniques. A total of 222 patients who underwent unilateral TKA using a Legion PS Total Knee System were randomized into 2 groups. PC incidence, time of PC presentation, radiographic parameters associated with PC development, and clinical outcomes were evaluated at 3, 6, 9, 12, 18, and 24 months postoperatively.

RESULTS

PC occurred significantly more in the onlay group (17.9% vs 6.5%, P = .009). Time of PC presentation in both groups was not different. Anterior knee pain was found in 11.5% of PC patients, and none required any surgical procedure. Postoperative radiographic parameters, range of motion, Knee Society score, Oxford score, patellar score, incidence and intensity of anterior knee pain, and visual analog scale of overall knee pain were not significantly different between the 2 groups during the follow-up period.

CONCLUSION

To reduce the chance of PC development, we suggest an inlay patellar resurfacing technique during PS-TKA with this knee system.

Risk Factors for Patellar Clunk or Crepitation after Primary Total Knee Arthroplasty: A Systematic Review and Meta-analysis

Patellar clunk and crepitation (PCC) have been reported as a consequence of primary total knee arthroplasty (TKA). The incidence and contributing factors have not been fully defined. We performed this systematic review to evaluate factors associated with PCC following primary TKA. We identified studies on PCC following TKA from an electronic search of articles in Medline, Embase and the Cochrane databases (dated up to May 2018). Eighteen studies altogether, including 600 cases of PCC within 8,131 TKAs, were included in the meta-analysis. Several factors including demographic, intraoperative, clinical variables, and radiographic measurements were pooled for meta-analysis. Among intraoperative and clinical variables, patients involved with patellar retention (odds ratio [OR] = 9.420; confidence interval [CI]: 5.770-13.070), lateral reticular release (OR = 2.818; CI: 1.114-7.125), and previous surgery (OR = 2.724; CI: 1.549-4.790) were more likely to having PCCs. Among radiographic measurements, increased anterior tibial offset (weighted mean difference [WMD] = 0.387; CI: 0.139-0.634), increased joint line changes (WMD = 1.325; CI: 0.595-2.055), and increased knee flexion angle (WMD = 3.592; CI: 1.811-5.374) were considered risk factors associated with PCC. Demographic factors (age, gender, body mass index [BMI], and diagnosis) and other reported radiographic measurements were not associated with PCCs. This study identified intraoperative variables (patellar retention and lateral reticular release), clinical variables (previous surgery), and radiographic measurements (increased anterior tibial offset, increased joint line changes, and increased postoperative knee flexion angle) that contribute to an increased risk for PCC. Modifiable factors (patellar retention and lateral reticular release) should be considered and addressed to limit the risk for PCC following TKA. Patients with conditions that may not be modifiable may benefit from counseling about their increased risks for PCC to limit potential dissatisfaction with their procedure.

Improving radiographic patello-femoral tracking in total knee arthroplasty with the use of a flexion spacer: a case-control study

PURPOSE

The purpose of this study was to compare the effectiveness of a flexion spacer in the clinical and radiological outcomes of patients who underwent total knee arthroplasty (TKA) and to compare these patients to a group of patients subjected to the same type of surgery but without the use of a flexion spacer. It was hypothesized that patients who underwent TKA using a flexion spacer would have better clinical and radiological outcomes than those without a flexion spacer in both short- and medium-term follow-ups.

METHODS

A consecutive series of patients undergoing TKA were included, yielding 20 patients in the study group. The control group was identified from the consultant database of the senior author, yielding 21 patients who underwent the same operation. All 41 patients received a Vanguard Knee System (Zimmer-Biomet, Warsaw, Indiana, USA). Cases were defined as those patients who had undergone TKA using a flexion spacer device for gap balancing; controls were defined as patients who had undergone TKA without the support of a flexion spacer device. Patients were clinically and radiographically evaluated at two consecutive follow-ups: T₁-13.1 ± 1.3 months and T₂-108 ± 6 months. Clinical evaluation was performed using the Knee Society Scoring System and the Western Ontario, McMaster Universities Osteoarthritis Index score. Radiographic evaluation included the femoral angle (α), the tibial angle (β), the sagittal femoral (γ) angle and the tibial slope (δ). Furthermore, the lateral patellofemoral angle (LPFA) and the Caton-Deschamps index were evaluated.

RESULTS

No statistically significant clinical differences were found between the two groups at T₁ and T₂; moreover, the clinical outcomes of the two groups were stable between the two follow-ups, with no significant improvement or worsening. Radiographic evaluation showed no difference in the two groups between T₁ and T₂; the only significant radiographic difference between the two groups concerned the LPFA (both at 30° and 60°) at each follow-up, which was significantly greater in cases than in controls (p = 0.001).

CONCLUSIONS

The current study demonstrates that the use of a flexion spacer significantly improves radiographic patello-femoral tracking, although no significant clinical differences were found between the two groups.

LEVEL OF EVIDENCE

Case-control study, level III.

Patellar Clunk Syndrome Following Posterior Stabilized Total Knee Replacement: Report of Two Cases

Patellar clunk syndrome (PCS) occasionally occurs after posterior stabilized total knee replacement (PS-TKR), and is characterized by a painful palpable audible clunk of the patella when the knee moves from flexion to extension. It has been classically attributed to the formation of fibrous nodule at the junction of the proximal pole of the patella and the undersurface of the distal quadriceps tendon. However, various intra-articular peripatellar proliferative fibrous formations have also been reported with a wide spectrum of symptoms, ranging from crepitation to frank patellar clunk. Treatment of the syndrome remains essentially surgical, and usually consists of resection of the fibrous nodules. This paper reports two cases of PCS and aims at bringing attention to this entity in terms of pathogenesis, clinical diagnosis, and treatment, through a review of the literature.

Comparative study on mid- and long-term clinical effects of medial pivot prosthesis and posterior-stabilized prosthesis after total knee arthroplasty

Objective

The purpose of this study was to explore the mid-and long-term clinical effects of Chinese patients with medial pivot (MP) prosthesis and posterior-stabilized (PS) prosthesis after total knee arthroplasty (TKA), to provide a reference for the recommendation of clinical prostheses.

Methods

A retrospective analysis of 802 patients who received TKA was performed from June 2010 to December 2013. A total of 432 patients received a MP prosthesis (MP group) and 375 patients received a PS prosthesis (PS group). Postoperative range of motion (ROM), clinical scores including the knee scoring system (KSS), the Western Ontario and McMaster Universities osteoarthritis index (WOMAC), the forgotten joint score (FJS), and postoperative complications were compared between the two groups.

Results

A total of 527 patients were followed up, including 290 in the MP group and 237 in the PS group. Both groups achieved satisfactory results in terms of KSS score, WOMAC score, and postoperative ROM, which were significantly improved compared with those before surgery, but the difference between the groups was not statistically significant (P > 0.05). The FJS scores of the MP group and the PS group were satisfactory and no significant difference was observed (P = 0.426). Postoperative complications occurred in 5 and 11 patients in the MP group and PS group, respectively.

Conclusion

The clinical results of TKA with MP or PS in Chinese patients at mid- and long-term are encouraging, and no significant differences were observed between the two types of prostheses. Studies have also shown that both prostheses are safe for Chinese patients.

Systematic review of the etiology behind patellar clunk syndrome

BACKGROUND

Total knee arthroplasty is one of the most successful operations performed worldwide today. Patellar clunk syndrome (PCS) is a postoperative complication that arises due to the development of a fibrous nodule along the undersurface of the quadriceps tendon. The current literature on PCS has not yet come to a consensus regarding its etiology. To date, this is the first study that analyzes the existing literature on PCS in order to generate a conclusion regarding its etiology. It is hypothesized that prosthesis design is the main component behind the development of PCS.

AIM

To determine the etiology of PCS and its association with pre and post-operative characteristics of the prosthesis and native knee.

METHODS

We conducted a systematic review according to the PRISMA guidelines by searching through PubMed, Cochrane, and Google Scholar from May-July 2018 for cases of PCS using search MeSH terms “patella OR patellar” AND “clunk” OR “catch” OR “crepitus”. The search included case series and clinical trials and excluded review articles, yielding 30 articles from the original search and 3 additional articles from reference lists. We extracted data upon the outcomes in patients afflicted with PCS to determine the etiology of PCS. We performed additional bias assessments to validate our search algorithm and results.

RESULTS

Prosthesis design was the metric most frequently implicated in the incidence of PCS, though several other metrics were contributory toward its pathogenesis. Later prosthetic designs incorporate a reduced intercondylar box ratio and box width to reduce contact between the proximal patellar pole and the intercondylar box, thereby reducing incidence of PCS.

CONCLUSION

The etiology of PCS is multifactorial, owing to the growing metrics that have associations with its incidence. This conclusion is validated by the significance of prosthesis design as the most likely parameter involved in developing PCS since different prosthesis designs are often the result of different parameters. Future studies should be directed at isolating individual prosthetic parameters of prosthesis designs in order to determine what permutation of parameters is most closely associated with the development of PCS.

Resurfacing in a Posterior-Stabilized Total Knee Arthroplasty Reduces Patellar Crepitus Complication: A Randomized, Controlled Trial

BACKGROUND

Patellar crepitus (PC) is a common complication after total knee arthroplasty (TKA) using a posterior-stabilized (PS) prosthesis. While numerous factors have been associated with PC development after PS-TKA, patellar resurfacing (PR) which directly impacts the patellofemoral joint kinematics has been underinvestigated. A prospective, randomized, controlled trial was conducted to (1) compare the PC incidence in PR and non-PR PS-TKA, (2) determine the time of PC presentation in PS-TKA, (3) identify radiographic parameters associated with PC, and (4) compare clinical outcomes of patients with and without PR.

METHODS

A total of 84 patients who underwent unilateral TKA using the Legion PS Total Knee System were randomized into PR group or non-PR group. PC incidence, time of PC presentation, radiographic parameters associated with PC development, and clinical outcomes were evaluated at 3 months, 6 months, 9 months, and 1 year postoperatively.

RESULTS

PC occurred significantly more in the non-PR group (23.1% vs 7.3%, P = .048). Time of PC presentation in both groups was not different. Anterior knee pain was found in 16.7% of crepitus patients, and none required any surgical procedure. The non-PR knees had significant decreases in patellar shift index, patellar displacement, Insall-Salvati ratio, and patellar component height and increase in change in posterior femoral offset. Oxford and patellar scores were significantly better in the PR group at 9 months and 1 year.

CONCLUSION

Given higher PC incidence and several worse clinical outcomes in the non-PR, we recommend resurfacing during PS-TKA with this knee system to avoid PC development.

Patellar Resurfacing versus Nonresurfacing with Patellaplasty in Total Knee Arthroplasty

BACKGROUND

Anterior knee pain following total knee arthroplasty (TKA) remains one of the important reasons for patient dissatisfaction. The management of patellofemoral joint is controversial and a decision whether to resurface the patella or not, is important. The present study compares the clinical and radiological outcomes between patellar resurfacing and nonresurfacing in patients undergoing bilateral TKA.

MATERIALS AND METHODS

This is a prospective comparative study with 60 patients undergoing bilateral simultaneous TKA (120 knees) with posterior stabilized Hi flex fixed bearing knee (Zimmer, Warsaw, Indiana), by two surgeons. The patients were allocated to the two groups of resurfacing versus nonresurfacing of patella. In nonresurfacing group, patellaplasty was done. Patients with clinicoradiological signs of tricompartmental arthritis were included in the study. Exclusion criteria included unilateral TKA, rheumatoid arthritis, postseptic arthritis, previous high tibial osteotomy, or unicondylar knee arthroplasty cases. Patients were assessed using Knee Society Score (KSS), Modified Samsung Medical Centre Score (MSMCS), Feller patellar score. Radiological evaluation was performed at 1 year using congruence angle and patellar tilt angle.

RESULTS

Mean followup was 19 months (range 12-25 months). Mean KSS, MSMCS, Feller patellar scores in resurfacing group were 82.67, 10.68, and 25.97, respectively and in nonresurfacing group were 82.93, 10.48, and 24.90, respectively. Mean congruence angle in resurfacing group was -12.83° and in nonresurfacing group was -12.383° (P = 0.917) and mean patellar tilt angle in resurfacing is 8.07 and nonresurfacing group is 7.97 (P = 0.873).

CONCLUSION

There was no statistically significant difference in short-term clinical, functional, and radiological outcomes in the two groups and therefore, routine patellar resurfacing for patient undergoing TKA is not advantageous.

Fracture of the polyethylene tibial post in a posterior stabilized knee prosthesis: A case report and review of literature

We report a case of fracture of tibial polyethylene post fracture from base in a 56 year old lady 10 years from posterior stabilized total knee arthroplasty following trivial trauma. There have been signs of wear at the base especially anteriorly. After revision of tibial polyethylene component patient developed complete relief of symptom.

Advantage of minimal anterior knee pain and long-term survivorship of cemented single radius posterior-stabilized total knee arthroplasty without patella resurfacing

BACKGROUND

The single radius total knee prosthesis was introduced with the advantage of reduced patellar symptoms; however, there is no long-term follow-up study of the same. The purpose of this study was to determine the survival rate of single radius posterior-stabilized total knee arthroplasty and patellofemoral complication rates in a consecutive series.

METHODS

Seventy-one patients (103 knees) who underwent arthroplasty without patellar resurfacing using a single radius posterior-stabilized total knee prosthesis were followed up for a minimum 10 years. Clinical evaluation using Knee Society knee and function scores and radiologic evaluation were performed at regular intervals. Anterior knee pain as well as patellofemoral complications were evaluated with a simple questionnaire. The Kaplan-Meier product-limit method was used to estimate survival.

RESULTS

Seventeen patients (23 knees) were excluded due to death (12 knees) or lost to follow-up (11 knees). Of the 80 knees enrolled, all femoral components and 78 tibial components were well fixed without loosening at final follow-up. Two revisions were performed because of tibial component loosening and periprosthetic joint infection. One patient with tibial component loosening refused to have revision surgery. No obvious tibial insert polyethylene wear was observed. The survivorships at 132 months were 96.7% using revision or pending revision as end points. Anterior knee pain was present in 6 patients (6 knees, 7.5%) at the latest follow-up. No patellofemoral complication requiring revision was encountered.

CONCLUSIONS

The single radius posterior-stabilized total knee prosthesis demonstrated an excellent minimum 10-year survivorship. The low rates of implant loosening and 7.5% of anterior knee pain as a patellofemoral complication are comparable with those reported for other modern total knee prosthesis.

Patellar clunk in total knee arthroplasty using modified Sigma posterior stabilized femoral component

AIM

The purpose of this study was to evaluate the efficacy of the enhanced PS femoral component design released in 2008 by DePuy. The patellar clunk syndrome has been reported in a significant number of patients following total knee arthroplasty. Design modifications of the implant have been made to reduce the incidence of the patellar clunk, especially in the posterior substituted designs.

METHODS

130 total knee replacements performed using the enhanced PS femoral components were followed-up with clinical and radiographic evaluations.

RESULTS

Patellar clunk was seen in 3 of the 130 knees (2%). This is much less than the incidence of patellar clunk reported until now.

CONCLUSIONS

Removal of the sharp ridge in the intercondylar groove in the newer implant seems to have been effective in reducing the incidence of the patellar clunk. It also indicates that the sharp ridge was the most probable cause of the clunk.

Incidence of patellar clunk syndrome in fixed versus high-flex mobile bearing posterior-stabilized total knee arthroplasty

The geometry of the intercondylar box plays a significant role in the development of patellar clunk syndrome. We reviewed the incidence of patella clunk at mid-to-long-term follow-up of a rotating high-flex versus fixed bearing posterior stabilized TKA design. 188-mobile and 223-fixed bearing TKAs were reviewed for complications, incidence of patellar clunk, treatment, recurrence rates, range of motion, and patient satisfaction. Patellar clunk developed in 22 knees in the mobile (11.7%) and in 4 (1.8%) in the fixed bearing group (P<0.001). 23 out of 26 cases resolved with a single arthroscopic treatment and 2 resolved with a second procedure. The mean postoperative range of motion was 122.4°. All but one patient reported overall satisfaction with the index procedure. In contrast with other recent studies we found a significant incidence of patellar clunk in high-flex mobile bearings. Despite the high rate of patellar clunk syndrome, overall patients did well and were satisfied with their outcomes.

Patellar clunk syndrome in fixed-bearing posterior-stabilised versus cruciate-substituting prostheses

PURPOSE

To compare the outcome of fixed-bearing posterior-stabilised versus cruciate-substituting prostheses in 46 patients who underwent primary bilateral total knee replacement (TKR).

METHODS

Records of 35 women and 11 men aged 54 to 78 (mean, 67) years who underwent primary bilateral TKR for osteoarthritis (n=44) and rheumatoid arthritis (n=2) were retrospectively reviewed. A fixed-bearing posterior-stabilised prosthesis (Zimmer NexGen Legacy flex [LPS-Flex]) was used in one knee, and a fixed-bearing cruciate-substituting prosthesis (Depuy Press Fit Condylar Sigma CS [PFC CS]) was used in the contralateral knee. The mean time interval between the 2 operations was 34 (range, 4-60) months. All operations were performed by the same group of surgeons using standardised techniques. The medial parapatellar approach was used, and the patella was resurfaced. Rehabilitation was also standardised. Outcome measures included the pre- and post-operative active range of movement and the American Knee Society Score. Postoperative complications were documented.

RESULTS

At one year, the mean fixed flexion contracture, maximum flexion, and American Knee Society scores in knees with PFC CS and LPS-Flex prostheses were comparable. Three knees with the PFC CS prosthesis developed the patellar clunk syndrome, compared to none with the LPS-Flex prosthesis (p=0.24). The onset of the patellar clunk syndrome was around one year after surgery. Despite this, the axial alignment and rotation of the femoral and tibial components were good.

CONCLUSION

Both prostheses produce good clinical outcome. The PFC CS prosthesis is more likely to be associated with the patellar clunk syndrome.

Can TKA design affect the clinical outcome? Comparison between two guided-motion systems

PURPOSE

In a retrospective comparative analysis in patients undergoing primary guided-motion total knee arthroplasty (TKA), the authors have evaluated whether different TKA implant design would influence the clinical and functional outcomes.

METHODS

Between 2007 and 2009, 227 computer-assisted primary TKAs were performed in 219 consecutive patients. Patients received one of the two different fixed-bearing guided-motion TKA designs assisted by navigation surgery: the Scorpio Non-Restrictive Geometry (NRG) knee system and the Journey Bi-Cruciate Stabilized (BCS) knee systems.

RESULTS

Data were available for 180 patients (187 knees). No significant differences were observed between the two groups with respect to preoperative demographic characteristics, range of motion (ROM) and radiographic knee alignment. At a mean follow-up of 29 months, the Journey BCS group had higher mean Knee Injury and Osteoarthritis Outcome Score (KOOS) in all subscales and a greater ROM than the Scorpio NRG group. This difference was statistically significant for the KOOS subscales of pain (p = 0.007) and knee-related quality of life (p = 0.045), as well as for postoperative ROM (p = 0.018). Considering the overall complications, 1 patient of Scorpio NRG group (0.5%) and 5 in Journey BCS (2.7%) had stiffness. Anterior knee pain was reported in 4 cases of Scorpio NRG group (2.1%). In the Journey BCS group were observed 2 cases (1.1%) of frontal plane instability and 1 case (0.5%) of synovitis pain.

CONCLUSIONS

The bearing geometry and kinematic pattern of different guided-motion prosthetic designs can affect the clinical-functional outcome and complications type in primary TKA.

LEVEL OF EVIDENCE

Clinical study, Level III.

Patellofemoral crepitation and clunk following modern, fixed-bearing total knee arthroplasty

Patellar crepitation and clunk (PCC) is an important and modifiable complication of total knee arthroplasty (TKA). We calculated the incidence of PCC using a modern fixed-bearing TKA prosthesis, assessed whether PCC is associated with knee range of motion, and determined if there were any radiographic variables associated with the development of PCC in this prosthetic design. Five hundred seventy primary TKAs were evaluated after a mean follow-up of 24 months (range 12-81). Thirty-four knees developed PCC (6%); 6 required arthroscopic debridement. With each degree increase in the flexion angle, the likelihood of developing PCC increased by 4.2%. The incidence of PCC was low but increased with postoperative flexion ≥ 110°. No radiographic parameters were associated with the development of PCC.

Patellofemoral crepitus after total knee arthroplasty: etiology and preventive measures

Patellofemoral crepitus and clunk syndrome are infrequent, yet troublesome complications of total knee arthroplasty with a reported incidence of 0%-18%. They are primarily associated with implantation of posterior cruciate substituting designs. These entities are the result of peripatellar fibrosynovial hyperplasia at the junction of the superior pole of the patella and the distal quadriceps tendon which becomes entrapped within the superior aspect of the intercondylar box of the femoral component during knee flexion. When the knee extends, a crepitant sensation occurs as the fibrosynovial tissue exits the intercondylar box. Numerous etiologies have been proposed such as femoral component designs with a high intercondylar box ratio, previous knee surgery, reduced patellar tendon length, thinner patellar components, reduced patella-patellar component composite thickness, and smaller femoral components. Preventative measures include choice of femoral components with a reduced intercondylar box ratio, use of thicker patellar components, avoidance of over-resection of the patella, and debridement of the fibrosynovial tissue at the time of knee arthroplasty. Most patients with crepitus are unaware of the problem or have minimal symptoms so that no treatment is required. If significant disability is incurred, symptoms can be eliminated in a high percentage of patients with arthroscopic debridement of the fibrosynovial hyperplasia.

Patellar clunk syndrome in a current high flexion total knee design

This retrospective study of 208 (204 patients) total knee arthroplasties evaluated the incidence of patellar clunk syndrome for two high-flex posterior stabilized knee prostheses; a high-flex fixed bearing prosthesis and a high-flex mobile bearing prosthesis. Patients were followed for up to two years and were evaluated for patellar clunk and component position. Knees receiving the mobile bearing had a significantly higher (p < 0.001) incidence of patellar clunk (15%) than knees receiving the fixed bearing (0%). There was a significantly higher incidence of patellar clunk in males (34.1%; p < 0.01) compared to females (8.6%). Fibrous nodules were treated surgically in 11 of the knees with patellar clunk. The design of this particular mobile bearing knee seems to contribute to patellar clunk syndrome.

Painful patellar clunk or crepitation of contemporary knee prostheses

BACKGROUND

Painful patellar clunk or crepitation (PCC) is a resurgent complication of contemporary posterior-stabilized TKA. The incidence, time to presentation, causes, and treatment of PCC still remain controversial.

QUESTIONS/PURPOSES

We therefore (1) compared the incidence of PCC with five contemporary TKA designs, (2) evaluated the time to presentation, (3) identified possible etiologies, and (4) determined recurrence rate and change in knee functional scores after treatment for PCC.

METHODS

We reviewed 580 patients who had 826 posterior-stabilized TKAs involving five different designs. The incidences of PCC were compared among the prostheses. The knees were divided into two groups depending on the development of PCC, and possible etiologic factors of PCC, including prosthesis design and surgical or radiographic variables, were compared between groups. We investigated the onset time of PCC and evaluated treatment results by knee outcome scores. Minimum followup was 2.0 years (mean, 3.9 years; range, 2.0-9.8 years).

RESULTS

The PCC incidence was higher in the Press-Fit Condylar(®) Sigma(®) Rotating Platform/Rotating Platform-Flex Knee System (11 of 113 knees, 9.7%) than in the others (seven of 713 knees, 1.0%). Increased risk of PCC was associated with using a specific prosthesis and patellar retention. PCC occurred in all cases within a year after TKA (mean, 7.4 months). Arthroscopic treatment (16 knees) and patellar replacement (two knees) improved knee scores, with no recurrence observed over an average followup of 29 months.

CONCLUSIONS

Prosthesis design and patellar retention were associated with PCC. Surgery resolved the PCC.

Effect of femoral component design on patellofemoral crepitance and patella clunk syndrome after posterior-stabilized total knee arthroplasty

The purpose of this study was to determine if recent changes to the femoral component of a particular posterior-stabilized total knee prosthesis would affect the incidence of postoperative patellofemoral crepitance and patella clunk syndrome. One hundred eight total knee arthroplasties were performed with the conventional design; 136 were performed after the femoral component was changed. Complications were compared between the groups with an average follow-up of 17.7 months and 12.4 months, respectively. Thirteen knees with the conventional design (12%) were found to have patellofemoral complications; no complications were noted with the new design (P < .0001). Femoral components with a deep trochlear groove and smooth transition of the intercondylar box appear to better accommodate any peripatellar fibrous nodule that may form after total knee arthroplasty.

Rotating-platform knee arthroplasty: a review and update

Fixed versus rotating-platform knee arthroplasty for total knee arthroplasty is still a controversial topic. In this article, biomechanical and clinical aspects of rotating-platform knee arthroplasty are reviewed. In regard to its biomechanical characteristics, the rotating-platform knee arthroplasty design has been proved to provide less tibiofemoral contact stress under conditions of tibiofemoral malalignment. It also reduces the wear rate. However, in regard to its clinical characteristics, the mid-term and long-term survivorship of rotating-platform knee arthroplasties is not superior to that of fixed-platform knees. It appears that we are at a crossroads. In this article, progress in biomechanical and clinical aspects of rotating-platform knee prosthesis is reviewed.

The natural history of anterior knee pain in 2 posterior-stabilized, modular total knee arthroplasty designs

Anterior knee pain (AKP) has been a persistent complaint after total knee arthroplasty; however, the natural course of this complaint has not been fully investigated. This is a 10-year follow-up report of a prospective, randomized study between the Insall-Burstein II (Zimmer, Warsaw, IN) and the Press Fit Condylar Modular (Johnson & Johnson, Raynham, MA) knees. Up to one third of total knee arthroplasties will experience mild to moderate AKP at 1-year follow-up, which will persist in approximately 30% of these previously symptomatic knees at 10-year follow-up. New-onset AKP will develop in approximately 10% of previously asymptomatic knees.

Prospective, randomized study between Insall-Burstein II and NexGen legacy with a minimum 9-year follow-up

A randomized, prospective, comparative study was performed in 2 related, adjacent generation posterior stabilized total knee prostheses, to evaluate whether the newer design improved the clinical and radiographic outcome for treatment of advanced osteoarthritis of the knee. Ninety one total knee arthroplasties in 84 patients (45 Insall-Burstein II and 46 NexGen Legacy posterior stabilized [both from Zimmer, Warsaw, Ind] prostheses) with an average of 10.3 years of follow-up (range, 9-11.8 years) were included. The preoperative diagnoses were primary osteoarthritis in all patients. At the latest evaluation, there were no significant differences detected in the mean clinical and functional knee scores, average postoperative active range of motion, and anterior knee pain between the Insall-Burstein II and the NexGen Legacy groups postoperatively.

Scorpio single radius total knee arthroplasty. A minimal five-year follow-up multicentric study

PURPOSE

Our goal was to evaluate the five-year follow-up results of the Scorpio single radius total knee arthroplasty.

METHOD

We performed a retrospective study based upon a multicentre database to evaluate the minimum five-year follow-up clinical and radiological results of 747 patients (831 knees) who underwent primary Scorpio single radius total knee arthroplasty.

RESULTS

The mean age of the patients was 71.9 years. At a minimal five-year follow-up, 141 patients were lost to follow-up, 83 patients had died, eight patients had undergone revision of a component, and the remaining 589 patients (602 knees) had a complete clinical and radiological evaluation after a median of six years (range, 5-8). The mean clinical component of the knee score was 92.2 points, and the mean functional component of the knee score was 76.9 points. At last follow-up, 530 of the 602 knees were rated as excellent or good. Only four knees developed patellar complications requiring revision. The survival rate at six years was 95.2% ± 1.9% and 98.3% ± 0.6 with revision for any reason and revision for mechanical failure as the end point, respectively.

CONCLUSION

This medium-term study indicates favourable clinical and radiological results for this single flexion-extension radius design arthroplasty, with a low complication rate on the patellar side.

Cruciate-retaining TKA using a third-generation system with a four-pegged tibial component: a minimum 10-year followup note

BACKGROUND

A third-generation TKA system was designed to address problems encountered with earlier designs including a high rate of patellofemoral complications. At a minimum of 5 years, we previously reported survivorship of 98.7% using revision for any reason as the endpoint for a cohort that includes the patients described in this report. That cohort was unique in that a tibial component that uses four short pegs for fixation was used in a subset of patients undergoing cruciate-retaining TKA and the tibial and femoral components were precoated with polymethylmethacrylate.

QUESTIONS/PURPOSES

We now report the survival rate, postoperative function, complications, radiographic loosening, and osteolysis at a minimum of 10 years postoperatively.

PATIENTS AND METHODS

We retrospectively reviewed 161 patients who underwent 179 TKAs. The patella was resurfaced in all cases and all components were cemented. Patients were evaluated clinically and radiographically for evidence of component loosening and osteolysis. Forty of the 161 patients (with 44 TKAs) had died and eight patients (nine knees) were lost to followup. For the remaining 113 patients (126 knees), the minimum followup was 10 years (mean, 11.7 years; range, 10.0-13.9 years).

RESULTS

Survivorship at a minimum of 10 years postoperatively using revision for any reason and revision for aseptic loosening were 97.7% and 100%, respectively. Three knees were revised: one for infection, one for periprosthetic fracture, and one for postoperative arthrofibrosis. There were no reoperations for patellar component maltracking, wear or loosening, tibiofemoral polyethylene wear, osteolysis, or aseptic loosening. Hospital for Special Surgery scores improved from a mean of 47.7 (range, 23-78) preoperatively to 85.4 (range, 33-100).

CONCLUSIONS

This cruciate-retaining design had a low risk of implant failure or revision and the design changes eliminated the patellar failures seen with earlier iterations at up to 10 years.

LEVEL OF EVIDENCE

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

The incidence of the patellar clunk syndrome in a recently designed mobile-bearing posteriorly stabilised total knee replacement

The patellar clunk syndrome describes painful catching, grinding or jumping of the patella when the knee moves from a flexed to an extended position after total knee replacement (TKR). The posterior stabilised TKR had been noted to have a higher incidence of this problem. Mobile-bearing posteriorly stabilised TKRs have been introduced to improve patellar tracking and related problems by a mechanism of self-alignment. We evaluated the patellar clunk syndrome in 113 knees in 93 patients with such a TKR at a mean follow-up of 2.3 years (2.0 to 3.2). The syndrome was identified in 15 knees (13.3%). Logistic regression analysis showed that the absolute value of the post-operative angle of patellar tilt was significantly associated with the occurrence of patellar clunk (p = 0.025). Patellar tracking should be carefully checked during surgery.

Comparison of the Insall-Burstein II and NexGen legacy total knee arthroplasty systems with respect to patella complications

This study retrospectively contrasts 2 cohorts of consecutive patients ""(N = 202) after primary total knee arthroplasty with respect to the types and numbers of patella and extensor mechanism complications. Our results demonstrated an overall decrease of patellofemoral complications associated with the NexGen Legacy PS system (Zimmer Inc, Warsaw, Ind). Patella fractures decreased from 6 to 0 (P = .013), avascular necrosis from 9 to 0 (P = .0002), and lateral retinacular release trended down from 24 to 14. The Insall-Burstein II (Zimmer Inc, Warsaw, Ind) has a significantly higher incidence of patella fractures, avascular necrosis, and the lateral retinacular release. We feel that the alteration and adjustment of the patellofemoral dimension in the NexGen Legacy design to a more anatomical, extended design of the femoral component and patella modifications led to a decrease in the incidence of complications.

Tibial post failures in a condylar posterior cruciate substituting total knee arthroplasty

In posterior-stabilized total knee arthroplasties, a femoral cam and polyethylene tibial post are commonly used to restore posterior stability after sacrifice of the posterior cruciate ligament. This article reports a high incidence of early tibial post failures in one design of prosthesis and examines the variables that may have contributed to such. Five hundred sixty-four consecutive posterior-stabilized total knees were implanted in 512 patients, using a total knee prosthesis with a polyethylene tibial post and femoral cam. Clinical and radiographic outcomes were measured at a mean follow-up of 40 months after surgery (range, 24-83 months). At follow-up, 70 knees in 62 patients (12%) had undergone revision surgery because of symptoms related to catastrophic failure of the tibial post.

Arthroscopic treatment of patellofemoral soft tissue impingement after posterior stabilized total knee arthroplasty

Patellar clunk syndrome is due to a suprapatellar fibrous nodule which develops at the junction between the proximal patella and the quadriceps tendon after total knee arthroplasty. Twelve patients (12 knees) who underwent arthroscopic treatment for the painful patellar crepitus or clunk after total knee arthroplasty had been followed at least for 1 year were enrolled. The average onset of symptom was 10.2 months (from 3 to 21 months) after total knee arthroplasty. All of the patients presented a painful crepitus, catching or clunk at the proximal patella, especially climbing stairs or rising from sitting. Both radiographic and clinical evaluations were done and for the clinical assessment, Knee Society Scores were recorded preoperatively and postoperatively. On their radiographic assessment, there was no evidence of component failure and in only one patient, joint line was elevated more than 8 mm. On arthroscopic examination, hypertrophic synovial tissue was identified at the junction of patella and quadriceps tendon in all patients. The hypertrophic synovial tissue did not engage completely in the intercondylar notch during flexion, but on extension, the lesion impinged on the distal part of anterior flange of femoral component at about 30 degrees to 40 degrees of knee flexion. On clinical assessment at the latest follow-up, the average knee score and function score increased from 63.8+/-4.6 to 90.9+/-3.2, 65.4+/-3.2 to 90.4+/-4.3 respectively. Arthroscopic debridement for soft tissue impingement at the patellofemoral joint following total knee arthroplasty showed satisfactory results.

Scorpio posterior-stabilized knee system: 5-year clinical and functional results

One hundred three primary total knee arthroplasties using the Scorpio posterior-stabilized total knee system were studied. Clinical, functional, and radiographic assessments were performed preoperatively and at 7 weeks, 6 months, and annually postoperatively. Standard knee scoring systems were used for clinical and functional evaluation. Radiographic assessment was characterized according to standard zones. Presence of anterior knee pain and patellar clunk was also noted. Mean follow-up was 5.25 years. At latest postoperative follow-up, follow-up was 89%. Knee Society scores were 91.3 clinical and 73.0 functional. Mean range of motion increased from a mean preoperative level of 96.5 degrees to 124.5 degrees at latest-year follow-up. There were 4 reports of anterior knee pain. One femoral and 1 tibial radiolucency were found. The Scorpio posterior-stabilized design (Stryker Orthopaedics, Mahwah, NJ) showed favorable midterm results compared with other posterior-stabilized designs.

The influence of femoral component design in the elimination of patellar clunk in posterior-stabilized total knee arthroplasty

Patellar clunk occurs after posterior-stabilized total knee arthroplasty and is believed to be a design-related complication. This study was undertaken to define the incidence of patellar clunk with an optimized third-generation, posterior-stabilized prosthesis. One hundred ninety three patients with 238 knees were evaluated at a minimum of 2 years after primary total knee arthroplasty with a cemented, NexGen Legacy Posterior-Stabilized prosthesis (Zimmer, Warsaw, Ind). The mean follow-up was 48 months (range, 24-72 months). No patient manifested symptoms of patellar clunk or underwent surgery for any patello-femoral problem. These results support prior evidence that femoral component design is the primary cause of patellar clunk and that modifications incorporated into this third-generation, posterior-stabilized prosthesis has eliminated the problem.

Natural history and pathogenesis of the patella clunk syndrome

INTRODUCTION

The current study aims to test the importance of the design of total knee prostheses in the 'patella clunk syndrome', which is one of the possible patellofemoral complications that can occur after total knee replacement.

MATERIALS AND METHODS

Three patient cohorts consisting of 75 consecutive patients with 80 Insall-Burstein II (IB II) total knee replacements; 57 patients with 60 Anatomic Modular Knee (AMK) total knee replacements; and 103 patients with 106 Low Contact Stress Rotating Platform (LCS) total knee replacements were studied during the period from 1995 to 2001. This was an unselected series of elderly patients with knee arthritis of comparable demographics; we excluded only those patients receiving revision surgery. We recorded the preoperative and postoperative Knee Society scores, and the patient subgroups with postoperative patellofemoral complications were analysed in detail and were serially followed up. Radiological analysis followed the recommendation of the Knee Society, and the degree of pain was recorded on a visual analogue scale. Also, since the majority of patients with patella clunk syndrome had refused operation and were followed up for several years, an idea of the natural history of this condition was obtained.

RESULTS

The relative frequency of occurrence of patella clunk syndrome among patients with the IB II, AMK, and LCS prostheses was 8.8%, 3.3%, and 0%, respectively. The calculated p value is strongly significant when comparing the IB II group with the LCS group (p<0.01); and of borderline significance when comparing the AMK with the LCS group (p=0.05); and not statistically significant between the IB II and AMK groups (p=0.19). Analysis of the results also showed that about half of the patients who underwent conservative treatment still had incapacitating symptoms after several years of follow-up, while the other half showed progressive improvement over time.

CONCLUSION

Given a good surgical technique in component placement and debridement of the peripatella synovium, the design of a total knee prosthesis has a strong bearing on the incidence of the patella clunk syndrome. The natural history of the patella clunk syndrome reveals that for as yet uncertain reasons about 50% will improve with time even when given conservative treatment.

Early results of posterior-stabilised NexGen Legacy total knee arthroplasty

OBJECTIVE

To retrospectively assess the early results of the NexGen Legacy posterior-stabilised total knee prosthesis, which is a newer version of the Insall-Burstein II posterior-stabilised implant.

METHODS

48 consecutive elderly patients had 60 NexGen Legacy posterior-stabilised total knees. The mean follow-up duration was 21 months. Clinical evaluation was performed according to the Knee Society scores and a scoring system for patellofemoral articulation; radiographic assessment followed the guidelines of the Knee Society. Special emphasis was given to any patellofemoral complications, such as patellar clunk syndrome, patellar maltracking, and other disorders of the extensor mechanism.

RESULTS

Only one patient had mild patellofemoral anterior knee pain at the latest follow-up; 2 patients had patellofemoral crepitus but no pain. No patellar clunk or any other complication of the patellofemoral articulation, such as patellar fracture or subluxation was found. The mean preoperative and postoperative Knee Society scores were 60 and 85 respectively. The mean postoperative knee flexion was 115 degrees.

CONCLUSION

The overall early results from using the new implant were good, probably because of changes in design of the intercondylar box and its associated cam-and-post mechanism, and a more anatomic trochlea surface, so that the trochlea accommodates the natural patella.

Insall Award paper. Why are total knee arthroplasties failing today?

The incidence of failure after knee replacement is low, yet it has been reported that more than 22,000 knee replacements are revised yearly. The purpose of the current study was to determine current mechanisms of failure of total knee arthroplasties. A retrospective review was done on all patients who had revision total knee arthroplasty during a 3-year period (September 1997-October 2000) at one institution. The preoperative evaluation in conjunction with radiographs, laboratory data, and intraoperative findings were used to determine causes of failure. Two hundred twelve surgeries were done on 203 patients (nine patients had bilateral surgeries). The reasons for failure listed in order of prevalence among the patients in this study include polyethylene wear, aseptic loosening, instability, infection, arthrofibrosis, malalignment or malposition, deficient extensor mechanism, avascular necrosis in the patella, periprosthetic fracture, and isolated patellar resurfacing. The cases reviewed included patients who had revision surgery within 9 days to 28 years (average, 3.7 years) after the previous surgery. More than half of the revisions in this group of patients were done less than 2 years after the index operation. Fifty percent of early revision total knee arthroplasties in this series were related to instability, malalignment or malposition, and failure of fixation.