Partial lateral patellar facetectomy as an alternative to lateral release in Total Knee Arthroplasty (TKA)

Factors that impact the patellofemoral contact stress in the TKA: a review

Abnormal retro patellar stress is believed to contribute to patellofemoral complications after total knee arthroplasty (TKA), but the causal link between TKA and patellofemoral contact stress remains unclear. By reviewing the relevant studies, we found that both TKA implantation and additional patellar resurfacing increase retro patellar pressure. The rotation and size of the femoral component, thickness and position of the patellar component, installation of the tibial component, prosthesis design and soft tissue balance further influence patellofemoral stress. Specific measures can be applied to reduce stress, including the installation of the femoral prosthesis with an appropriate external rotation angle, placing the tibial component at a more posterior position and the patellar button at a more medial position, avoiding over-sized femoral and patellar components, selecting posterior-stabilized design rather than cruciate-retaining design, using gender-specific prosthesis or mobile-bearing TKA system, and releasing the lateral retinaculum or performing partial lateral facetectomy. Despite these measures, the principle of individualization should be followed to optimize the patellofemoral biomechanics.

Does Choice of Patellar Implant in Total Knee Arthroplasty Matter?: A Randomized Comparative Trial of 3 Commonly Used Designs

BACKGROUND

There is currently a lack of evidence to identify the optimal patellar implant design in total knee arthroplasty (TKA). The aim of this study was to assess clinical, intraoperative, radiographic, and scintigraphic differences between inlay (IN), onlay round (OR), and onlay oval (OO) patellar implants.

METHODS

A parallel-group, double-blinded, randomized trial compared IN, OR, and OO patellar implants using the same posterior-stabilized TKA prosthesis for each. Patient outcomes were prospectively followed for a minimum of 2 years, with survivorship outcomes followed for a mean of 5 years. The primary outcome was the between-group differences in the mean Kujala score change from preoperatively to 2 years postoperatively. The secondary outcomes included differences in other knee-specific and general health outcomes, intraoperative characteristics, radiographic parameters, patellar vascularity, and implant survivorship.

RESULTS

A total of 121 participants (40 in the IN group, 41 in OR group, 40 in the OO group) were allocated to 1 of 3 implant designs. At 2 years postoperatively, there were no significant differences in Kujala score changes between groups (p = 0.7; Kruskal-Wallis test). Compared with the IN group, the OR group showed greater improvements in Knee injury and Osteoarthritis Outcome Score (KOOS) Activities of Daily Living and in KOOS Quality of Life compared with the OO group. However, the OO design exhibited better bone coverage and lower lateral facetectomy rates compared with the IN and OR designs. The IN group had more lateral contact compared with the OO group (p = 0.02; Fisher exact test), but the overall value for lateral contact was not significant (p = 0.09; chi-square test). There were no differences in postoperative scintigraphic vascularity (p = 0.8; chi-square test). There was 1 revision for infection at 3 years postoperatively in the OO group, and no revision in the other groups.

CONCLUSIONS

Patellar design did not influence patellofemoral outcomes or survivorship. However, OR implants showed improvements in some secondary patient-reported outcome measures, and OO implants exhibited superior bone coverage and improvements in several intraoperative, radiographic, and scintigraphic outcomes. These findings, combined with superior long-term implant survivorship from previous studies, add support for the use of onlay designs in TKA.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Management of patella maltracking after total knee arthroplasty: a systematic review

PURPOSE

Patella maltracking is among the most frequent causes of poor outcomes and early failure after total knee arthroplasty (TKA), with an incidence that ranges from 1 to 20%. Even if there is agreement between authors regarding the preoperative and intraoperative management of patella maltracking in TKA, less clear are postoperative conducts. The purpose of this systematic review is to summarize and compare surgical techniques used to treat patella maltracking after TKA.

METHODS

A systematic review of the literature was performed with a primary search on Medline through PubMed. The PRISMA 2009 flowchart and checklist were used to edit the review. Screened studies had to provide clinical, functional and radiological results and complications of the proposed treatment to be included in the review.

RESULTS

A total of 21 articles were finally included. Three main types of surgical procedures and other minor techniques have been identified to manage patella maltracking after TKA. The choice of the proper technique to use in the specific case depends on several factors, first of all the malpositioning of the prosthetic components.

CONCLUSION

Patella maltracking after TKA represents a frequent and challenging problem for orthopedic surgeons. Treatments described in the literature are often able to correct an abnormal patellar tracking; nevertheless, authors report variable percentages of residual knee pain and dissatisfaction in re-treated patients. Therefore, it would be desirable to prevent the maltracking condition at the time of primary arthroplasty, using proper surgical precautions.

Lateral Patellar Facetectomy Reduces the Incidence of Anterior Knee Pain in Patellar Resurfaced Total Knee Arthroplasty

Lateral patellar facet impingement (LPFI) can cause anterior knee pain (AKP) after patellar resurfaced total knee arthroplasty (TKA). Recently, lateral patellar facetectomy (LPF), which has been used for LPFI, has been performed during primary TKA, providing good clinical outcomes. However, the effect of LPF on AKP in primary patellar resurfaced TKA has not been sufficiently studied. The purpose of this study was to examine the effect of LPF on the development of AKP in patellar resurfaced TKAs with minimum follow-up of 3 years. This retrospective cohort study included 84 knees of 66 consecutive patients who underwent patellar resurfaced TKA between April 2007 and November 2014 in our hospital. The subjects were divided into two groups: TKA with LPF (LPF group; 47 knees) and TKA without LPF (no-LPF group; 37 knees). Postoperative AKP, the primary outcome, the Japanese Orthopaedic Association (JOA) score, and range of motion were investigated at the final visit and compared between the two groups. Six knees (16.2%) had AKP in the no-LPF group, whereas none of the knees had AKP in the LPF group at the final visit. The incidence of AKP was significantly lower in the LPF group (p = 0.004). The postoperative JOA score and flexion angle were significantly higher in the LPF group than in the no-LPF group. LPF correlated with less incidence of postoperative AKP and improved the JOA score and knee flexion angle. In patellar resurfaced TKA, LPF may be considered an additional maneuver to avoid postoperative AKP.

New treatment of patellar instability after total knee arthroplasty: A case report and review of literature

BACKGROUND

Patellar instability is an uncommon complication after total knee arthroplasty (TKA). Partial lateral patella facetectomy (LPF) with lateral retinaculum release treatment of patellar instability is rarely reported.

CASE SUMMARY

We present a case of patellar instability 8 mo after primary TKA. Treatment of this complication was adapted to address the cause of the dislocation. To eliminate patellar instability, we restored the vastus medialis and performed LPF with lateral retinaculum release. We achieved normal patellar tracking. Clinical and radiographic evaluations at the 1-year postoperative follow-up were satisfactory.

CONCLUSION

LPF with lateral retinaculum release represents a promising option to restore central patellar tracking in patients with patellar instability after TKA in cases without component malposition.

Does total contact of the patella with the femoral trochlea during no thumb test significantly reduce anterior knee pain?

BACKGROUND

Complications such as anterior knee pain (AKP) and crepitus continue to be causes of dissatisfaction after total knee arthroplasty (TKA). This prospective study aimed to study the significance of total patellar contact with the femoral trochlea of the implant, with the no thumb test during trial reduction, and its effect on reducing AKP.

METHODS

Between 2014 and 2016, 445 patellofemoral joints (M:F 126:319, age 45-80 years) and their contact with the trochlea of the femoral component were graded at trial reduction without lateral retinaculum release (Grades I, Ia, II, III based on existing publications). The aim was to restore all patellae to pre-operative thickness. Posterior stabilized implants with a domed patella were used in all cases. The Knee Society Score (KSS) and Visual Analogue Scale (VAS) score were noted at follow up between 12 and 24 months after surgery.

RESULTS

AKP was significantly lower with 100% patellofemoral contact. The KSS and VAS had statistically significant P-values of 0.021 and 0.025 in Grade I and Ia contact, respectively. Better results were achieved where patellar thickness was restored in Grades I and Ia with P-values of 0.041 and 0.046 for VAS change and 0.038 and 0.044 for KSS change, respectively.

CONCLUSION

At follow up, superior results were obtained where there was a complete patellofemoral contact at trial reduction in Grade I and Grade Ia, and when other confounding factors such as patellar thickness and normal rotation of the femoral and tibial components were standardized. To minimize AKP it is imperative to have total patellar contact with the femoral trochlea.

Understanding the patellofemoral joint in total knee arthroplasty

Total knee arthroplasty (TKA) is one of the most successful procedures in orthopedic surgery. Nevertheless, postoperative patellofemoral complications remain a challenging problem, affecting a substantial proportion of patients. Complications involving the patellofemoral joint (PFJ) can occur in both resurfaced and nonresurfaced patellae. Types of PFJ complications include anterior knee pain, maltracking, fracture, avascular necrosis and patellar clunk. The causes of patellofemoral complications can be categorized into patient-, surgeon- and implant-related factors. Patient characteristics such as female sex, young age, depression and increased body mass index have been linked with increased complications. Important technical considerations to avoid complications include achieving appropriate rotational alignment of the femoral and tibial components, maintaining joint line height, medializing the patellar button and avoiding “overstuffing” the PFJ. Component design features such as conformity, shape and depth of the femoral trochlea have also been shown to be important. Although the cause of patellofemoral complications after TKA may sometimes be unknown, it remains important to minimize errors that can lead to these complications.

Patellar complications after total knee arthroplasty

Patellar complications are a source of poor total knee arthroplasty (TKA) outcomes that can require re-operation or prosthetic revision. Complications can occur with or without patellar resurfacing. The objective of this work is to answer six questions. (1) Have risk factors been identified, and can they help to prevent patellar complications? Patellar complications are associated with valgus, obesity, lateral retinacular release, and a thin patella. Selecting a prosthetic trochlea that will ensure proper patellar tracking is important. Resurfacing is an option if patellar thickness is greater than 12mm. (2) What is the best management of patellar fracture? The answer depends on two factors: (a) is the extensor apparatus disrupted? and (b) is the patellar implant loose? When either factor is present, revision surgery is needed (extensor apparatus reconstruction, prosthetic implant removal). When neither factor is present, non-operative treatment is the rule. (3) What is the best management of patellar instability? Rotational malalignment should be sought. In the event of femoral and/or tibial rotational malalignment, revision surgery should be considered. If not performed, options consist of medial patello-femoral ligament reconstruction and/or medialization tibial tuberosity osteotomy. (4) What is the best management of patellar clunk syndrome? When physiotherapy fails, arthroscopic resection can be considered. Recurrence can be treated by open resection, despite the higher risk of complications with this method. (5) What is the best management of anterior knee pain? The patient should be evaluated for causes amenable to treatment (fracture, instability, clunk, osteonecrosis, bony impingement on the prosthetic trochlea). If patellar resurfacing was performed, loosening should be considered. Otherwise, secondary resurfacing is appropriate only after convincingly ruling out other causes of pain. A painstaking evaluation is mandatory before repeat surgery for anterior knee pain: surgery is not in order in the 10% to 15% of cases that have no identifiable explanation. (6) What can be done to treat patellar defects? Available options include re-implantation (with bone grafting, cement, a biconvex implant, or a metallic frame), bone grafting without re-implantation, patellar reconstruction, patellectomy (best avoided due to the resulting loss of strength), osteotomy, and extensor apparatus allograft reconstruction. LEVEL OF EVIDENCE: V, expert opinion.

Osteophytes removal in patella versus lateral facetectomy of the patella in patella-retaining total knee arthroplasty

BACKGROUND

In this study, the results of the partial lateral facetectomy of the patella to better patellofemoral motion and congruence are compared with the results of the osteophyte removal of the patella and neurectomy only in total knee arthroplasty (TKA).

METHODS

Data from 55 patients undergoing TKA with osteophytes removal of the patella and neurectomy only, and those undergoing osteophytes removal of the patella and neurectomy and partial lateral facetectomy were reviewed retrospectively. Clinical outcomes were evaluated by knee society score (KSS) and functional score of knee. Clinical anterior knee pain (AKP) rating and knee range of motion and extension lag were assessed for each patient.

RESULTS

There was significant difference between two groups in AKP (p < 0.05), and the mean range of motion of the knee in groups 1 and 2 was 117° ± 9° and 116.6° ± 8.2°, respectively. Three (13%) patients of the reshaped patella group and three (11%) patients of the non-reshaped patella group had extension lag <10°, respectively. The mean KSS and knee functional scores showed no statistical difference between groups (p > 0.05).

CONCLUSION

Partial lateral facetectomy of the patella can decrease AKP and can be used routinely for every patient that surgeon does not decide to resurface the patella.

Lateral facetectomy decreased patellofemoral contact pressure in total knee replacement: A cadaveric study

BACKGROUND

To study the patellofemoral contact pressure in patellar non-resurfacing total knee replacement after lateral facetectomy in different amounts of bone removal.

METHODS

Eight knees from four fresh-frozen whole body cadavers were used for this study. Total knee replacement of all knees was performed by the same surgical technique. The contact pressure was measured and recorded when the knee performed passive motion from full extension to full flexion in native patella, lateral retinacular junction release, 10% lateral facetectomy, and 20% lateral facetectomy.

RESULTS

Peak patellofemoral contact pressure decreased progressively from native patellar, junctional release of the patella, 10% facetectomy, and 20% facetectomy. The peak patellofemoral contact pressures were statistically significantly different in each patellar condition (p = 0.025).

CONCLUSION

In the experimental study, lateral facetectomy can reduce the peak patellofemoral contact pressure in patellar non-resurfacing total knee arthroplasty.

The effect of tourniquets on patellofemoral joint congruity during total knee arthroplasty

BACKGROUND

Incongruity of the patellofemoral joint after total knee arthroplasty (TKA) causes anterior knee pain. Intraoperative congruity tests are necessary to avoid unnecessary lateral retinacular release, and the usage of tourniquets may influence these results. The purpose of this study was to examine the effect of tourniquets on patellofemoral joint congruity during TKA.

MATERIALS AND METHODS

Two hundreds and seventeen knees were examined after TKA. Skyline radiographs at 60° and 90° flexion were taken immediately after wound closure before and after tourniquet deflation to compare changes in patellar tilt angle.

RESULTS

In the patellar tilt angle at 60° flexion, lateral tilt was observed in 18 knees. Tourniquet deflation changed the patellar tilt angle by a mean -0.7° ± 1.2° (p = 0.030). Medial tilt was observed in 10 knees. Tourniquet deflation changed the patellar tilt angle by 0.9° ± 0.7° (p = 0.004). Tourniquet deflation improved the degree of lateral and medial patellar tilt. In the patellar tilt angle at 90° flexion, lateral tilt was observed in 118 knees. Tourniquet deflation changed the patellar tilt angle by a mean -1.1° ± 1.2° (p < 0.001). Medial tilt was observed in 71 knees. Tourniquet deflation changed the patellar tilt angle by 0.5° ± 1.0° (p < 0.001). Tourniquet deflation improved the degree of lateral and medial patellar tilt.

CONCLUSIONS

Tourniquet deflation improved patellofemoral congruity in a statistically significant way, but only to a small extent, indicating low clinical significance. Therefore, intraoperative congruity tests performed with tourniquets in place are reliable.

[Extensor mechanism complications in revision total knee arthroplasty : Joint exposure and prevention of extensor mechanism complications]

BACKGROUND

Revision total knee arthroplasty is complex surgery that has to be well planned from its indication to the actual surgical procedure.

OBJECTIVES

To review surgical techniques that allow a secure exposure of the joint in revision total knee arthroplasty.

MATERIALS AND METHODS

The authors summarize a review of the literature and present their own experience in knee joint exposure aiming to minimize extensor mechanism complications in revision TKA.

RESULTS

The choice of adequate skin incision, detailed scar removal and a systematic soft tissue release are inevitable prerequisites for an optimal joint exposure and the minimization of extensor mechanism complications. In most patients, a medial parapatellar arthrotomy is sufficient to expose the knee joint and, if necessary, allows a proximal extension using a quadriceps snip or VY-quadricepsplasty, or a distal extension via a tibial tubercle osteotomy. Whether the quick and easy quadriceps snip or a tibial tubercle osteotomy has to be performed depends in each case on the extent of scar formation, the extensor mechanism contracture and the preoperative position of the patella. In general, a parapatellar and lateral release has to be executed; therefore, a partial lateral facetectomy ensures a secure eversion of the patella. Alternative approaches to access the joint do not reveal significant advantages and play a minor role in revision total knee arthroplasty.

CONCLUSION

Revision total knee arthroplasty is a challenging surgical procedure. In addition to the regular soft tissue release techniques and joint approaches, the surgeon has to be aware of proximal and distal extension procedures to securely expose the joint and minimize the risk of extensor mechanism complications.