Evaluating the "Patella-Friendly" Concept in Total Knee Arthroplasty: A Minimum 15-Year Follow-Up Outcome Study Comparing Constant Radius, Multiradius Cruciate-Retaining, and Nonanatomical Cruciate-Retaining Implants

Patella is rarely resurfaced during primary total knee arthroplasty in clinical trials conducted in Greece: a systematic review

PURPOSE

The aim of the present study was to report the approach of Greek surgeons regarding patellar management and provide the outcomes and the rate of the need for secondary patella resurfacing.

METHODS

Following the PRISMA guidelines, PubMed, Scopus, and The Cochrane Central Register of Controlled Trials (CENTRAL) databases were accessed in January 2024. Clinical studies evaluating the outcomes of patients undergoing primary TKA were considered eligible for this systematic review if the following predefined criteria were fulfilled: (1) published in English, (2) were conducted in Greece, and had a minimum of 2-year follow-up. The methodological quality and publication bias were assessed using the Modified Coleman Methodology Score (mCMS) and ROBIS tool, respectively. Data was presented in tables using absolute values from individual studies. Pooled data were presented as means, ranges, and percentages.

RESULTS

Six clinical studies with a total of 1084 TKAs were included. Four studies were retrospectives, and two studies were prospective. Patella was only resurfaced in 0.6% of total TKAs. TKA without patellar resurfaced, which resulted in an improvement in functional outcome. Among studies, the overall need for revision incidence was 7.6% (68 out of 892 TKAs). Additionally, Aseptic loosening (2.4%) was the most common reason for revision due to patellofemoral joint complications, followed by secondary patellar resurfacing (2.1%) and deep infection (1.3%). The mean mCMS demonstrated a fair methodological quality level, and the ROBIS toll a low risk of bias in all four domains.

CONCLUSION

The available evidence supports that Greek surgeons mainly do not resurface the patella. However, patellar non-resurfacing yields good functional outcomes and presents relatively low revision rates for secondary patellar resurfacing.

LEVEL OF EVIDENCE

IV.

Incidence of Anterior Knee Pain and Functional Difficulty in a Prospectively Recruited Cohort Following Total Knee Arthroplasty With Selective Patellar Resurfacing

BACKGROUND

The influence of patellar resurfacing on anterior knee pain, stair climbing, and functional activity outcomes following total knee arthroplasty (TKA) are incompletely understood. This study examined the influence of patellar resurfacing on patient-reported outcome measures (PROMs) relating to anterior knee pain and function.

METHODS

The Knee Injury and Osteoarthritis Outcome Score of Joint Replacement (KOOS, JR.) patient PROMs were collected preoperatively and at 12 months follow-up for 950 TKAs performed over 5 years. Indications for patellar resurfacing included Grade IV patello-femoral (PFJ) changes or mechanical PFJ findings during patellar trialing. Patellar resurfacing was performed on 393 (41%) of the 950 TKAs performed. Multivariable binomial logistic regressions were performed, using KOOS, JR. questions assessing pain during stair climbing, standing upright, and function during rising from sitting as surrogates for anterior knee pain. Independent regression models were performed for each of the targeted KOOS, JR. questions, with adjustment for age at surgery, sex, and baseline pain and function.

RESULTS

No association was observed between 12-month postoperative anterior knee pain or function with patellar resurfacing (P = .17, .97). Patients who had moderate or greater preoperative pain on stairs had an increased likelihood of postoperative pain and functional difficulty (odds ratio 2.3, P = .013), while males were 42% less likely to report postoperative anterior knee pain (odds ratio 0.58, P = .002).

CONCLUSION

Selective patellar resurfacing based on PFJ degeneration and mechanical PFJ symptoms produces similar improvement in PROMs for resurfaced and unresurfaced knees.

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.

Decreased Trochlear Length Associated with Increased Anterior Knee Pain Following Total Knee Arthroplasty: A New Anatomical Perspective

BACKGROUND

Anterior Knee Pain (AKP) and patello-femoral crepitus (PFCr) continue to plague total knee arthroplasty (TKA) patients despite advances and modifications to implant design and surgical techniques. We present our study of the femoral trochlear length measurement pre- and post-implantation and its association with AKP/PFCr and clinical scores.

METHODS

Using computer navigation, we obtained several measurements in 263 TKA (posterior-stabilized) patients, which included femoral native trochlear measurement (NTM) and difference in trochlear length (DTL) between implant and native trochlea. We report their association with Knee Society Score (KSS), Western Ontario McMaster University Arthritic Index(WOMAC), and AKP/PFCr at 1 year postoperatively.

RESULTS

Mean KSS and WOMAC Scores were significantly worse in patients who had AKP (P=0.005 and P=0.002 respectively). Receiver Operating Characteristic (ROC curve) showed a statistically significant association between native trochlear measurement and AKP (Area under the curve[AUC] =0.609, P=0.014). Lower the native trochlear measurement, greater was the incidence of AKP. Analysis of the ROC curve identified the cut-off value of NTM to be ≤ 25.5 with sensitivity of 76.7(95% Confidence Interval (CI)- 57.7 - 90.1) and specificity of 46.9(95%CI- 41.9 - 55.1). Patients who had NTM of ≤25.5 had an odds ratio of 3.09 to have AKP. The DTL ranged from 7.4 to 32.1 millimeters, indicating that post-implantation there was lengthwise overstuffing along the trochlea in every patient.

CONCLUSION

We found that the shorter the native femoral trochlea and greater the difference between implanted and native trochlea, the higher was the occurrence of AKP. A mismatch in trochlear measurement pre- and post-implantation resulted in lengthwise overstuffing in the anterior knee causing AKP and PFCr.

Patellar resurfacing was not associated with a clinically significant advantage when a modern patellar friendly total knee arthroplasty is employed: A systematic review and meta-analysis

BACKGROUND

Modern total knee arthroplasty (TKA) femoral components are designed to provide a more optimal articular surface for the patella whether or not it has been resurfaced. Previous systematic reviews comparing outcomes of patellar resurfacing and no resurfacing combine both historic and modern designs.

AIMS

The aim of this study was to investigate the effect of patellar resurfacing in modern "patellar friendly" implants on (1) incidence of anterior knee pain, (2) patient reported outcomes (3) complication rates, and (4) reoperation rates compared with unresurfaced patellae in primary TKA.

METHODS

MEDline, PubMed and google scholar studies were evaluated using SIGN assessment tool and data analysis was conducted using Review Manager 5.2 on only randomised controlled trials. The search terms were: arthroplasty, replacement, knee (Mesh), TKA, prosthesis, patella, patellar resurfacing, patellar retaining.

RESULTS

Thirty-two randomised controlled studies were identified that reported the type of TKA implant used: 11 used modern "patellar friendly" implants; and 21 older "patellar non-friendly" implants. Among "patellar friendly" TKAs there were no significant differences in anterior knee pain rates between resurfaced and unresurfaced groups. Patellar resurfacing with "patellar friendly" implants had significantly higher clinical (mean difference (MD) -0.77, p = 0.007) and functional (MD -1.87, p < 0.0001) knee society scores (KSS) than unresurfaced counterparts but these did not exceed the minimal clinically important difference (MCID). Resurfacing with "patellar friendly" implants was not associated with a significant (p = 0.59) difference in the Oxford knee score (OKS), in contrast when a "patellar non-friendly" implant was used there was a significant difference (MD 3.3, p = 0.005) in favour of resurfacing. There was an increased risk of reoperation for unresurfaced TKAs with "non-patellar friendly" implants (Odds ratio (OR) 1.68, 95% CI 1.03-2.74, p = 0.04), but not for unresurfaced patellae with "patellar friendly" implants (OR 1.17, CI 0.59-2.30).

CONCLUSIONS

Patellar resurfacing in combination with a modern patellar friendly implant was not associated with a lower rate of anterior knee pain, complications, or reoperations compared to not resurfacing, nor did it give a clinically significant improvement in knee specific function. In contrast patellar resurfacing in combination with a "non-friendly" TKA implant was associated with a significantly better OKS and lower reoperation rate. Implant design should be acknowledged when patellar resurfacing is being considered.

Patellofemoral cartilage defects are acceptable in patients undergoing high tibial osteotomy for medial osteoarthritis of the knee

BACKGROUND

Patients suffering cartilage defects of the medial compartment with underlying varus deformity do benefit from high tibial osteotomy (HTO) even in the long term. Nonetheless, kinematic and geometric changes especially in the patellofemoral joint have been described. Purpose of the present study was to evaluate the influence of patellofemoral cartilage defects detected during the diagnostic arthroscopy and their influence on HTO's postoperative outcome.

METHODS

Ninety patients with a mean follow-up of 10.08 ± 2.33 years after surgery were included. Patients were divided into four groups according to their cartilage status in the patellofemoral joint (A = no defects, B = isolated lesions of the patella, C = isolated lesions of the trochlea, D = kissing lesions). Functional outcome was evaluated before surgery and about ten years thereafter by relying on the IKDC, Lysholm, and KOOS scores. Radiological parameters were assessed pre- and six weeks postoperatively.

RESULTS

In groups A to D, the HTO led to significant patellar distalisation in the sagittal view, with the mean indices remaining at or above the limit to a patella baja. All patients in all groups profited significantly from HTO (higher Lysholm score, lower VAS p < 0.001), patients in group D had the lowest outcome scores. Patella height negatively influenced outcome scores in group C (Blackburne-Peel-Index-VAS p = 0.033) and D (Caton-Deschamps-Index-Tegner p = 0.018), a larger valgus correction was associated with lower outcome scores in group D (Lysholm p = 0.044, KOOSpain 0.028, KOOSQOL p = 0.004).

CONCLUSION

Long-term results of HTO for varus medial compartment osteoarthritis remain good to excellent even in the presence of patellofemoral defects. Overcorrection should be avoided. Distal biplanar HTO should be considered for patients presenting trochlear or kissing lesions of the patellofemoral joint.

TRIAL REGISTRATION

DRKS00015733 in the German Registry of Clinical Studies.

Intraoperative analysis of patellofemoral joint morphology before and after total knee arthroplasty

Background

Patellofemoral problems after total knee arthroplast (TKA) are frequent and often associated with a change in the geometry of the trochlear groove.

Objective

The present study aimed to analyze the feasibility of intraoperative examination of the patellofemoral joint geometry before and after the implantation of bicondylar total knee replacements without exposing the patient to radiation.

Material and methods

The patellofemoral joint morphology geometries of 33 patients before and after implantation of a bicondylar total knee replacement was intraoperatively analyzed using a digital scanning method. Femoral surface geometries were extracted from intraoperatively recorded tactile scanning data using an in-house algorithm. The geometries were then characterized by sulcus height, medial femoral condyle height and lateral femoral condyle height.

Results

Our preliminary results show that these key geometric parameters are only partially restored after TKA leading to a distinctly different shaped profile of the anterior distal femur. Maximum and minimum mean differences in sulcus height, medial femoral condyle height, and lateral femoral condyle height before and after surgery were 2.00 mm/−3.06 mm, 2.51 mm/−6.25 mm and 2.74 mm/−3.58 mm, respectively.

Conclusion

A new method for intraoperative analysis of the patellofemoral joint morphology before and after TKA without radiation exposure was developed and utilized. Even with the use of modern total knee designs, the patellofemoral articulation is considerably changed postoperatively as quantified by the key parameters of sulcus height, medial femoral condyle height, and lateral femoral condyle height. This may result in altered knee biomechanics and might explain persistent patellofemoral disorders, which are often reported by patients after TKA.