Patellar resurfacing in total condylar knee arthroplasty. Technique and results

Lateral Retinacular Release During Medial Unicompartmental Knee Arthroplasty in the Presence of Patello-Femoral Joint Arthritis Relieves Patello-Femoral Joint Pressure and Improves Associated Symptoms

BACKGROUND

This study evaluated the effects of concomitant lateral patellar retinacular release (LPRR) during medial unicompartmental knee arthroplasty (UKA).

METHODS

We retrospectively analyzed 100 patients who had patello-femoral joint (PFJ) arthritis who underwent medial UKA with (n = 50) and without (n = 50) LPRR who had ≥2 years follow-up. Radiological parameters associated with lateral retinacular tightness, including patellar tilt angle (PTA), lateral patello-femoral angle (LPFA), and congruence angle, were measured. Functional evaluation was performed using the Knee Society Pain Score, Knee Society Function Score (KSFS), Kujala Score, and the Western Ontario McMaster Universities Osteoarthritis Index score. Intraoperative patello-femoral pressure evaluation was performed on 10 knees to evaluate the pressure changes before and after LPRR. Mann-Whitney U-tests were used for statistical analyses.

RESULTS

Demographic data did not differ between the LPRR(+) and LPRR(-) groups. A decrease in PTA and an increase in LPFA were observed in the LPRR(+) group compared to those in the LPRR(-) group (PTA; -0.54 versus -1.74, P = .002, LPFA; 0.51 versus 2.01, P = .010). The LPRR(+) group showed significantly better KSFS and Kujala scores than the LPRR(-) group (KSFS: 90 versus 80, P = .017; Kujala score: 86 versus 79, P = .009). Intraoperative patello-femoral pressure analysis showed a 22.6% reduction in the PFJ contact pressure and an 18.7% reduction in PFJ peak pressure after LPRR. (P = .0015, P < .0001, respectively) CONCLUSION: A LPRR during UKA may be a simple and useful adjunct procedure to relieve PFJ symptoms with concomitant PFJOA.

Prospective comparative study of intraoperative "Towel clip test" and "Vertical patella test" assessing lateral retinaculum tightness in patients undergoing TKA

BACKGROUND

Proper patellar tracking is one of the most important aspect of TKA to ensure good functional outcome. A patellar tracking problem noted intraoperatively serves as a warning sign and should prompt the surgeon to reassess position of each component. Various tests are there to assess lateral retinaculum tightness viz. "No thumb test", "Towel clip test". A new test "Vertical patella test" is described to assess lateral retinaculum tightness. A study was conducted to assess the effectiveness, correlation and validity of two techniques.

MATERIALS & METHODS

Patients >50 years of age and with diagnosis of Osteoarthritis knee having less than 30 varus and flexion deformity going in for primary TKA were selected with a sample size of 100 knees in a tertiary care centre. Revision cases or patients with flexion contracture more than 30, complex knee surgery; with pre existing patellar tilt were excluded from study.

RESULTS

Results of both tests were found to correlate in 75% of case with sensitivity of 96.65% and specificity of 75.00%. Kappa came out to be 0.634 which shows good agreement of vertical patella test and towel clip test. Result was computed using excel and SPSS and was found to be significant with p value< 0.05. Lateral retinaculum release was done in 8 knees.

CONCLUSIONS

Vertical patella test correlates with towel clip test, is easy to perform and saves time. The limitation of our study was small sample size.

The influence of malalignment and ageing following sterilisation by gamma irradiation in an inert atmosphere on the wear of ultra-high-molecular-weight polyethylene in patellofemoral replacements

Complications of patellofemoral arthroplasty often occur soon after implantation and, as well as other factors, can be due to the design of the implant or its surgical positioning. A number of studies have previously considered the wear of ultra-high-molecular-weight polyethylene patellae following suboptimal implantation; however, studies have primarily been carried out under a limited number of degrees of freedom. The aim of this study was to develop a protocol to assess the wear of patellae under a malaligned condition in a six-axis patellofemoral joint simulator. The malalignment protocol hindered the tracking of the patella centrally in the trochlear groove and imparted a constant 5° external rotation (tilt) on the patella button. Following 3 million cycles of wear simulation, this condition had no influence on the wear of ultra-high-molecular-weight polyethylene patellae aged for 4 years compared to well-positioned non-aged implants (p > 0.05). However, under the malaligned condition, ultra-high-molecular-weight polyethylene patellae aged 8-10 years after unpacking (following sterilisation by gamma irradiation in an inert atmosphere) and worn ultra-high-molecular-weight polyethylene components also aged 4 years after unpacking (following the same sterilisation process) exhibited a high rate of wear. Fatigue failure due to elevated contact stress led to delamination of the ultra-high-molecular-weight polyethylene and in some cases complete failure of the patellae. The results suggest that suboptimal tracking of the patella in the trochlear groove and tilt of the patella button could have a significant effect on the wear of ultra-high-molecular-weight polyethylene and could lead to implant failure.

Should the position of the patellar component replicate the vertical median ridge of the native patella?

BACKGROUND

In total knee arthroplasty (TKA), the position of the patellar component can affect patellar tracking. However, the patellar component cannot always replicate the original high point of the patella because of anatomical variance. This study investigated whether altering the highest point of the patella can affect outcomes of primary TKA, especially in patients having a patella with a far-medialized median ridge.

METHODS

A retrospective review was performed for 177 knees (143 patients) treated with primary TKA between July 2011 and March 2014. Group 1 (34 knees) had the patellar component displaced over three millimeters from the median ridge, while Group 2 (143 knees) had the patellar component placed on the original median ridge position. The one-year follow-up outcomes were reviewed, including: patellar tilt angle, Knee Society Score, Feller Patellar Score, and modified Kujala Anterior Knee Pain Score.

RESULTS

Mean (±standard deviation) displacement of the patellar component in Group 1 was 3.97±0.97mm lateral to the original position of the median ridge, with a significant decrease in lateral patellar tilt angle (P<0.001). Lateral patellar tilt showed a positive correlation with the medialization of the patellar component (P<0.001, r=0.401). Ability to rise from a chair was better in Group 1 (P=0.025). There were no other between-group differences in other clinical outcomes.

CONCLUSIONS

There should be no need for the patellar component to replicate the original highest point of the native patella in primary TKA.

Decreased ratios of lateral to medial patellofemoral forces and pressures after lateral retinacular release and gender knees in total knee arthroplasty

PURPOSE

To demonstrate that lateral to medial patellofemoral force and pressure ratios could be a surrogate marker of retinacular tension and patellar tracking.

METHODS

The patellofemoral forces of six knees from three fresh-frozen half-body female cadavers were evaluated with a capacitive sensor under simulated operative conditions in six staged clinical scenarios: native knees, knee arthroplasty without patellar resurfacing, resurfaced knee and patella, resurfaced knee and patella with lateral release, gender-specific knee arthroplasty with patella resurfacing, and gender-specific knee arthroplasty with lateral release. Maximum force and peak pressure were simultaneously recorded during three to four ranges of motion. Average values were compared between lateral and medial patellofemoral compartments as an objective measure of patellar tracking for the different settings.

RESULTS

Significant differences in lateral and medial force and pressure differentials were seen in most scenarios despite clinically normal patellar tracking. Lateral to medial ratios of maximum force and peak pressure significantly increased after TKA (2.9, 2.1) and after patella resurfacing (2.8, 2.6) compared to the native knee (1.6, 1.8). Addition of a lateral release in resurfaced knees decreased the ratio of lateral to medial patellofemoral forces and pressures as did gender knee arthroplasty (1.5 and 1.1, 2 and 1.3, respectively). Pressure and force values most closely resembled the native knee in the resurfaced knee/resurfaced patella with lateral release and in the gender knee arthroplasty scenarios.

CONCLUSIONS

Use of lateral to medial patellofemoral force ratios as a surrogate objective marker for patellar tracking was validated in this study by decreasing ratios observed after lateral release in TKA and with gender-specific implants.

Medium-term evaluation of total knee arthroplasty without patellar replacement

Objective

To mid-term evaluate patients who were submitted to total knee arthroplasty without patellar resurfacing.

Methods

It was realized a retrospective cross-sectional study of patients who were submitted to total knee arthroplasty without patellar resurfacing. In all patients clinical examination was done based on the protocol of the Knee Society Scoring System, which assessed pain, range of motion, stability, contraction, knee alignment and function, and radiological evaluation.

Results

A total of 36 patients were evaluated. Of these, 07 were operated only on left knee, 12 only on right knee and 17 were operated bilaterally, totaling 53 knees. Ages ranged from 26 to 84 years. Of the 53 knees evaluated, 33 (62.26%) had no pain. The maximum flexion range of motion averaged 104.7°. No knee had difficulty in active extension. As to the alignment for anatomical axis twelve knees (22.64%) showed deviation between 0° and 4° varus. Thirty-nine (75.49%) knees showed pace without restriction and the femorotibial angle ranged between 3° varus and 13° valgus with an average of 5° valgus. The patellar index ranged from 0.2 to 1.1.

Conclusion

Total knee arthroplasty whitout patellar resurfacing provides good results in mid-term evaluation.

Lateral patellar facetectomy had improved clinical results in patients with patellar-retaining total knee arthroplasty

To evaluate the functional outcome of a partial lateral facetectomy in patellar-retaining total knee arthroplasty (TKA), we retrospectively analyzed 63 knees of 59 patients who underwent TKA for primary knee osteoarthritis with (32 knees of 30 patients, group 1) or without (31 knees of 29 patients, group 2) patellar facetectomy from September 2005 to July 2007. All cases were followed up for a minimum of 36 months. Although there was no significant differences between the 2 groups in preoperative patellar score, Western Ontario and McMaster Universities score, knee and function scores, postoperatively, group 1 showed more significant improvements in the scores and fewer lateral patellar osteophytes in radiographs than group 2. A partial lateral facetectomy is an effective way to improve the function of patellar-retaining TKA in patients with primary osteoarthritis.

Results of total knee replacement with/without resurfacing of the patella

OBJECTIVE

To study the difference of post-op patellofemoral pain, clunk and crepitus in patients with/without resurfacing at 5 years who had pre-op patellofemoral pain. To study the incidence of post-operative patellofemoral pain, clunk and crepitus following patelloplasty in both the groups.

METHODS

Retrospective review of 765 patients who had total knee replacement with/without resurfacing.Patients were asked about both pre-operative pain and also post-operative pain 5 years after the operation. Patients were examined by a specialist nurse at 5 years post-operatively to check for any patellofemoral clunk/crepitus.

CONCLUSION

In patients with pre-op PF pain, there is significant (p<0.005) higher incidence of post-op clunk in the R group. In patients without pre-op PF pain, there is significantly (p<0.005) higher incidence of post-op crepitus in the R group. In patients with/without pre-op PF pain, the incidence of post-op PF pain, clunk and crepitus is lower than in patients who underwent patelloplasty when compared to the other members of the NR group (statistically significant p<0.005).

LEVEL OF EVIDENCE

Type 4, Case series .

Should the 'no thumb technique' be the golden standard for evaluating patellar tracking in total knee arthroplasty?

We checked intraoperative patellar tracking with both 'towel clip technique' and the 'no thumb technique' on 97 patients (167 knees) who underwent primary total knee arthroplasty to decide whether to do or not to do lateral retinacular release. Patellar tracking was assessed under pneumatic tourniquet with the no thumb technique first and re-evaluated with the towel clip technique. The tracking was graded as total contact, good contact, lateral contact and subluxation. The knees graded as total or good contact with the no thumb technique were classified into group A; those graded lateral contact or subluxation by the no thumb technique but total or good contact by the towel clip technique were classified into group B; and those graded lateral contact or subluxation by both techniques were classified into group C; in which lateral releases were performed. One hundred three, 53 and 11 knees were classified into groups A, B and C respectively. Of the 167 knees, 64 (38.3%) showed poor tracking (lateral contact or subluxation) with the no thumb technique alone. Re-evaluation of these knees with the towel clip technique significantly reduced the number with poor tracking to 11 (6.6%) knees requiring lateral retinacular release (p < 0.05). The patients were followed up for 1 year without any patella-related complications occurring. Assessment of the patellar tracking using only the no thumb technique may overestimate the need for lateral retinacular release. The use of the no thumb technique as a screening test, and re-evaluation with the towel clip technique may reduce unnecessary lateral retinacular release.

Increased bone mineral density in the non-resurfaced patella after total knee arthroplasty: a clinical and densitometric study

We report the results of a longitudinal study of 40 patients with osteoarthritis who had primary prosthetic replacement without patellar resurfacing, and were followed at 6 months postoperatively with a densitometric study and clinically at a minimum follow-up of 2 years. Densitometric analysis showed a mean preoperative density at the affected knee of 0.69 g/cm(2) (CI: 0.62-0.76), compared to 0.86 g/cm(2) (CI: 0.79-0.93) for the opposite knee (p = 0.002). In our study population, the return to load and motion to the retained patella led to a significant increase in patellar bone density as measured by densitometry studies. This observation correlated with significant improvement in knee functional score.

The outerbridge classification predicts the need for patellar resurfacing in TKA

Patellar resurfacing (PR) in total knee arthroplasty (TKA) is controversial. The Outerbridge classification of cartilage defects in the patella is commonly used in the literature. The purpose of this study was to determine if the Outerbridge classification can predict the need for PR as part of total knee arthroplasty. Between 1995 and 2000, we performed a prospective, randomized study of 500 TKAs. We carried out PR depending on the Outerbridge classification of the patella at the time of surgery. Patients with Outerbridge Grades I, II, and III formed Group A, whereas patients with Grade IV formed Group B. Within each group, resurfacing was completed on half of the patients. Group A had 328 patients (164 with PR, 164 without PR). In Group B, there were 172 patients (86 with PR, 86 without PR). An identical prosthetic design was used for both groups. The minimum followup was 5 years (average, 7.8 years) for both Group A and Group B. At the end of followup, we assessed the number of patients in each group that required secondary resurfacing as a result of patellofemoral pain. Patients in Group A required fewer revisions for PF pain. In Group A, only one patient required a secondary PR (0.6% rate), whereas in Group B, 10 patients needed PR (11.6% rate). In Group B, the risk of need of a patellar resurfacing was 21.5 times greater than in Group A. On the basis of these findings, we recommend PR in Outerbridge Grade IV patellae, but not in Grades I, II, and III.

LEVEL OF EVIDENCE

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

A technique of staged lateral release to correct patellar tracking in total knee arthroplasty

Optimal patellar tracking and component alignment are important in achieving a well-functioning total knee arthroplasty (TKA). The patella is constrained partly by design of the prosthetic trochlear groove, and patellar tracking is governed by a combination of static and dynamic factors. Maltracking may result from excessive or unbalanced tension in the surrounding soft tissues. This article describes a staged progressive lateral release of the patellar retinaculum in TKA, which is classified into 6 stages. Stage 1 transects the deep lateral patellofemoral ligament; stages 2 to 6 extend the lateral patellar incision distally from vastus lateralis to the tibial tubercle. This technique was used in a series of 96 primary TKAs. We report the rates of the various stages of lateral release and the variables that might affect the decision to perform such a release.

A meta-analysis of patellar replacement in total knee arthroplasty

From individual randomized studies it is unclear whether the patella should be replaced during total knee replacement. We did a meta-analysis to provide quantitative data to compare patellar resurfacing with nonresurfacing during total knee arthroplasty. Only randomized, controlled trials reported between January 1966 and August 2003 comparing patellar replacement with patella retention were included for a total of 12 studies. Two reviewers assessed trial quality and extracted data from papers. The outcomes identified were reoperations for patellar problems, anterior knee pain, knee scores, stair climbing, and patient satisfaction. The resurfaced patella performed better, and we found an increased relative risk (defined by the ratio of the risk of the event in the resurfaced group on the risk of the event in the nonresurfaced group) for reoperation, for significant anterior knee pain, and for significant pain during stair climbing when the patella was left unresurfaced. No differences were observed between the two groups for International Knee Society function score, Hospital for Special Surgery score, and for patient satisfaction. Despite these general findings, forming a definitive conclusion is difficult because many confounding factors, such as component design, surgeon experience, and technical aspects of the surgery, might influence the result in a patient.

Total knee replacement and patellofemoral pain

BACKGROUND

The decision to resurface the patella or not during total knee replacement (TKR) is a controversial issue. During primary TKR some surgeons routinely resurface the patella, others operate a selective policy and a third group never resurfaces the patella.

AIM

This study attempts to investigate the relationship of patellofemoral knee pain and TKR.

MATERIALS AND METHODS

This was a prospective, non-randomised, multi-centre outcome study of 638 primary Insall Burstein II total TKRs, and their effect upon patellofemoral pain. Of those enrolled 378 knees had pre-operative patellofemoral pain; 236 of these underwent patella resurfacing and 142 did not. There were no statistically significant differences in the post-operative incidence of patellofemoral pain between the groups treated with resurfacing of the patella and those in which the patella was left intact. In those knees that developed patellofemoral pain after TKR there was no significant difference as to whether the knee had had resurfacing done or not.

CONCLUSION

Given that the cost of patella resurfacing is not insubstantial and that there are well-known complications resulting from it, we conclude that the role of patellar resurfacing for patellofemoral pain in knee arthritis remains unclear.

Mesh expansion release of the lateral patellar retinaculum during total knee arthroplasty

BACKGROUND

Release of the lateral patellar retinaculum can be used to treat patellofemoral instability and to balance the extensor mechanism during knee replacement operations. However, conventional lateral release disrupts the integrity of the lateral knee capsule, may damage the blood supply to the patella, and is associated with several other potential complications. Mesh expansion release of the lateral patellar retinaculum was developed to achieve the goal of lateral release and to reduce the potential for postoperative morbidity.

METHODS

Thirteen consecutive knees in eleven patients were treated with mesh expansion lateral release during a total knee arthroplastyand were evaluated after a minimum duration of follow-up of two years. The mesh release technique consisted of multiple, longitudinal, parallel 5 to 10-mm stab incisions to mesh and expand the lateral patellar retinaculum and thereby medialize the patella in the trochlear groove of the femoral implant.

RESULTS

Mesh expansion lateral release balanced the extensor mechanism in each knee, maintained the mechanical integrity of the lateral capsule, and avoided disruption of the lateral genicular blood supply to the patella. After a minimum duration of follow-up of two years, no complications had been noted in association with mesh expansion lateral release.

CONCLUSIONS

Mesh expansion release of the lateral patellar retinaculum effectively balanced the patellofemoral joint during total knee arthroplasty, maintained the integrity of the lateral capsule, and preserved the lateral genicular blood supply.

Secondary patellar resurfacing in total knee arthroplasty: results of multivariate analysis in two case-matched groups

Although patellofemoral symptoms after patellar-retaining knee arthroplasty are common, no evidence has been published in the literature on the potential benefit from patellar resurfacing at a later stage. This study evaluates the effect of secondary (delayed) patellar resurfacing using comparisons between 2 case-matched groups of patients with primary and secondary patellar resurfacing. Furthermore, multivariate statistical methods were applied to study factors that may influence the final outcome. Our results suggest that although significant clinical improvement was seen after delayed patella resurfacing, the outcome of secondary patellar resurfacing is inferior to that expected for a similar group of patients with primary resurfacing. Furthermore, the timing (delay period) of the secondary resurfacing procedure appears to negatively affect the final outcome. This suggests that secondary patellar resurfacing, when indicated, should be considered at an early stage.

Mesh expansion release of the lateral patellar retinaculum during total knee arthroplasty

BACKGROUND

Release of the lateral patellar retinaculum can be used to treat patellofemoral instability and to balance the extensor mechanism during knee replacement operations. However, conventional lateral release disrupts the integrity of the lateral knee capsule, may damage the blood supply to the patella, and is associated with several other potential complications. Mesh expansion release of the lateral patellar retinaculum was developed to achieve the goal of lateral release and to reduce the potential for postoperative morbidity.

METHODS

Thirteen consecutive knees in eleven patients were treated with mesh expansion lateral release during a total knee arthroplasty and were evaluated after a minimum duration of follow-up of two years. The mesh release technique consisted of multiple, longitudinal, parallel 5 to 10-mm stab incisions to mesh and expand the lateral patellar retinaculum and thereby medialize the patella in the trochlear groove of the femoral implant.

RESULTS

Mesh expansion lateral release balanced the extensor mechanism in each knee, maintained the mechanical integrity of the lateral capsule, and avoided disruption of the lateral genicular blood supply to the patella. After a minimum duration of follow-up of two years, no complications had been noted in association with mesh expansion lateral release.

CONCLUSION

Mesh expansion release of the lateral patellar retinaculum effectively balanced the patellofemoral joint during total knee arthroplasty, maintained the integrity of the lateral capsule, and preserved the lateral genicular blood supply.

Patellar resurfacing in total knee arthroplasty. A prospective, randomized study

BACKGROUND

Anterior knee pain following total knee arthroplasty is a common complaint and typically is attributed to the patellofemoral joint. The purpose of the present study was to compare the outcome of resurfacing and nonresurfacing of the patella, particularly with regard to anterior knee pain, and to clarify the indications for patellar resurfacing at the time of total knee arthroplasty.

METHODS

We performed a prospective, randomized study of 514 consecutive primary press-fit condylar total knee replacements. The patients were randomized to either resurfacing or retention of the patella. They were also randomized to either a cruciate-substituting or a cruciate-retaining prosthesis as part of a separate trial. The mean duration of follow-up was 5.3 years (range, two to 8.5 years), and the patients were assessed with use of the Knee Society rating, a clinical anterior knee pain score, and the British Orthopaedic Association patient-satisfaction score. The assessment was performed without the examiner knowing whether the patella had been resurfaced. At the time of follow-up, there were 474 knees. Thirty-five patients who had a bilateral knee replacement underwent resurfacing on one side only.

RESULTS

The overall prevalence of anterior knee pain was 25.1% (fifty-eight of 231 knees) in the nonresurfacing group, compared with 5.3% (thirteen of 243 knees) in the resurfacing group (p < 0.0001). There was one case of component loosening. Ten of eleven patients who underwent secondary resurfacing had complete relief of anterior knee pain. The overall postoperative knee scores were lower in the nonresurfacing group, and the difference was significant among patients with osteoarthritis (p < 0.01). There was no significant difference between the resurfacing and nonresurfacing groups with regard to the postoperative function score. Patients who had a bilateral knee replacement were more likely to prefer the resurfaced side.

CONCLUSIONS

As the present study showed a significantly higher rate of anterior knee pain following arthroplasty without patellar resurfacing, we recommend patellar resurfacing at the time of total knee replacement when technically possible.

Patellar resurfacing in total knee arthroplasty: a prospective, randomized trial

BACKGROUND

The management of the patella in total knee arthroplasty is still problematic. We aimed to identify differences in the clinical outcome of total knee arthroplasty according to whether or not patellar resurfacing had been performed in a prospective, randomized study of 220 osteoarthritic knees.

METHODS

Two hundred and twenty total knee arthroplasties in 201 patients were randomly assigned to be performed with either resurfacing or retention of the patella, and the results were followed for a mean of forty-eight months (range, thirty-six to seventy-nine months) in a double-blind (both patient and clinical evaluator blinded), prospective study. Evaluation was performed annually by an independent observer and consisted of assessment with the Knee Society clinical rating system, specific evaluation of anterior knee pain, a stair-climbing test, and radiographic examination.

RESULTS

Fifteen (12%) of the 128 knees without patellar resurfacing and nine (10%) of the ninety-two knees with patellar resurfacing underwent a revision or another type of reoperation related to the patellofemoral articulation. This difference was not significant (chi square with one degree of freedom = 0.206, p = 0.650). At the time of the latest follow-up, there was a significantly higher incidence of anterior pain (chi square with one degree of freedom = 5.757, p = 0.016) in the knees that had not had patellar resurfacing.

CONCLUSIONS

Patients who underwent patellar resurfacing had superior clinical results in terms of anterior knee pain and stair descent. However, anterior knee pain still occurred in patients with patellar resurfacing, and nine (10%) of the ninety-two patients in that group underwent a revision or another type of reoperation involving the patellofemoral joint. Weight but not body mass index was associated with the development of anterior knee pain in the patients without patellar resurfacing, a finding that suggests that patellofemoral dysfunction may be a function of joint loading rather than obesity.

Should the patella be resurfaced at total knee replacement?

Total knee replacement (TKR) presumably is replacement of the total knee articular surface. Sometimes it is and sometimes it is not. It is this author's firm conviction that the patella should be resurfaced in the vast majority of cases. Such advocacy must be critically justified and the potential drawbacks and alternatives examined.

Evaluation of patellar retinacular tension during total knee arthroplasty. Special emphasis on lateral retinacular release

Tension of a suture placed to the patella to close the medial capsule during 35 primary total knee arthroplasties was measured. The increase in tension with flexion after arthrotomy was significantly smaller in 10 knees with a subvastus incision (subvastus group) than in 25 knees with a standard medial parapatellar incision (standard group). With the prosthesis in place, the patella showed maltracking with the no-thumb technique in 1 knee (10%) of the subvastus group and in 9 knees (36%) of the standard group. A lateral retinacular release was performed in 5 of these 10 knees but not in the remaining 5 knees because the increase in tension was a minimum. There was no case of patellar maltracking at an average follow-up period of 2.1 years after surgery, suggesting that a lateral release is not always needed if retinacular tension shows no significant increase, even cases where the patella dislocates with the no-thumb technique.

Early patellofemoral revision following total knee arthroplasty

A consecutive series of 289 Miller-Galante (Zimmer, Warsaw, IN) total knee arthroplasties were studied, with particular reference to the patellofemoral joint. Sixteen knees were initially excluded; the remaining 273 arthroplasties were followed for 14 to 44 months. Thirty patients (11%) had patellofemoral pain. Twenty patients (7.3%) had revision patellofemoral surgery. Fourteen patients had revision surgery for patellar maltracking, of which 10 had resolution of their symptoms, 2 were improved, 1 had no change, and 1 developed a prosthetic infection. Six patients who had no evidence of patellar maltracking had revision surgery with a cemented metal-backed patellar component. Only two of these patients had symptom improvement from their revision surgery. A higher than usual incidence of patellar maltracking (5%) is reported. The first-generation Miller-Galante femoral component may contribute to the relative instability of patellofemoral tracking. Those patients with patellar maltracking were greatly improved by revision surgery; the results of revision surgery for anterior knee pain without associated patellar maltracking were disappointing.

Clinical comparison of the Miller Galante I and AMK total knee systems

One hundred patients with primary osteoarthritis of the knee were prospectively randomized to assess the clinical outcome between two contemporary knee designs, namely the Anatomic Modular Knee (AMK, DePuy, Warsaw, IN) and the Miller Galante I (MG I, Zimmer, Warsaw, IN). In addition, patients were stratified by surgeon. While the clinical outcome measured by the Hospital for Special Surgery knee scores was similar for both groups, there was a difference in the number of complications requiring further surgery. Extensor mechanism complications requiring further surgery occurred in four patients (3 MG I and 1 AMK); three patients in the MG I group required a distal realignment procedure for patellar dislocation, while none of the AMK patients had this complication. There was, however, one patellar fracture in the AMK group that required an open reduction. The authors postulate that the major difference contributing to patellofemoral complications relates to the patellofemoral design and patellar tracking, with the more anatomic AMK femoral component having better patellar tracking and stability clinically.