Pre-operative patella alta does not affect midterm clinical outcomes and survivorship of patellofemoral arthroplasty

Abstract

Purpose The purpose of this study was to evaluate the efect of preoperative patella alta on clinical outcomes, survivorship, and complication and reoperation rates on patellofemoral arthroplasty (PFA). Methods All patients who underwent PFA for isolated patellofemoral arthritis by a single surgeon at our institution were identiied. Preoperative radiographs were measured by two independent observers for patellar height using the Caton Deschamps (CD), Insall-Salvati (IS), and Blackburne-Peele (BP) methods. Patients were classiied as either "patella alta" or "non-patella alta" for all three measurement methods. Clinical scores including KSS Pain, KSS Function, and Tegner Activity Scores were collected pre-and post-operatively. Failure was deined as conversion to total knee arthroplasty (TKA). Clinical outcomes and survivorship were compared between patients with "patella alta" and "non-patella alta" height measurements. Results There were 119 patients with 153 knees (86% female) included in the study with a mean age of 55.8 years. Outcome scores improved from pre-operative to post-operative for both patella alta and non-patella alta patients for Tegner, KSS pain and KSS function scores. The mean change in Tegner scores for patella alta and non-patella alta patients were not signiicantly diferent for CD (p = 0.24), IS (p = 0.25) or BP measurements (p = 0.39). The mean change in KSS pain scores between groups were not signiicantly diferent for CD (p = 0.33) or IS measurements (p = 0.22), but was improved more signiicantly in patella alta patients vs non-patella alta patients (21.2 and 14.4; p = 0.02) for BP measurement. The mean change in KSS function scores between groups was not signiicantly diferent for CD (p = 0.61) IS (p = 0.90) or BP measurements (p = 0.79). The overall survivorship from conversion to total knee arthroplasty (TKA) was 94.1% at a mean follow-up time of 5.0 (SD 2.6) years. There were no signiicant diferences in survivorship from TKA between patella alta and non-patella alta groups (CD: p = 0.72, IS: p = 0.63, BP: p = 0.66). Conclusions This study suggests that there are no signiicant diferences in clinical outcome scores or survivorship from TKA between patella alta and non-patella alta patients who underwent onlay design PFA. Both patella alta and non-patella alta patients demonstrated excellent improvement in outcome scores from pre-operative to post-operative. Level of evidence IV.

Patellofemoral arthroplasty with onlay prosthesis leads to higher rates of osteoarthritis progression than inlay design implants: a systematic review

“…Regarding KSS, almost all of the nine analysed studies reported an increase in both postoperative clinical/objective scores and functional scores, when compared to preoperative ones [5, 7, 12, 19, 30, 35, 43, 50]. Both currently circulating variants of KSS were used (KSS 1989 and KSS 2011).…”

“…Another weakness is the retrospective type of the majority of the included studies, which could have led to an unknown selection bias. Another important aspect is that there are no studies reporting at mid-and long-term follow ups regarding the new inlay type of prosthesis, meaning that safe conclusions, with regards to the clinical and functional [38] 16 HemiCap Wave 24.1 (6-34) 1 (6.3%) 0 (0.0%) Metcalfe [32] 558 Avon 180 (nm) 61 (10.9%) 61 (10.9%) Ajnin [2] 43 FPV 65 (30-119) 5 (11.6%) 6 (13.9%) Bohu [10] 30 Hermes 240 (nm) 9 (30.0%) 9 (30.0%) Imhoff [22] 24 HemiCap Wave 60 (nm) 0 (0.0%) 6 (25.0%) Rammohan [42] 103 Journey 60 (± 12, 24-108) 9 (8.7%) 2 (1.9%) Bernard [7] 153 Avon 60 (± 30) 9 (5.9%) 9 (5.9%) Pogorzelski [40] 62 HemiCap Wave 60 (± 25) 12 (19.4%) 12 (19.4%) Marullo [30] 120 Gender Solutions 84 (± 30, 24-142) 5 (4.2%) 1 (0.8%) outcomes, and the survivorship of this type of prosthesis should be drawn with all due caution. Lastly, many authors were consultants for the companies designing the type of prostheses investigated in the respective studies, which might have led to a conflict of interest.…”

Modern Patellofemoral Arthroplasty

“…Similarly, patella alta and trochlear dysplasia are significantly more frequent in PFOA with an increase in both trochlear angle and Dejour score noted by Mofidi et al 47,48 . PFA can reduce patella height; however, this has not been quantified and the effect of patella height on the overall outcome of PFA is uncertain with the literature showing mixed results 44,48-50 . Beckmann et al concluded that patients with patella alta are contraindicated for an inlay design based on their 2019 study showing a high rate of revision for patella clunk after PFA with the inlay HemiCAP Wave implant 51 .…”

Patella height influences patellofemoral contact and kinematics following cruciate‐retaining total knee replacement

“…In PF arthroplasty, clinical results are also controversial. Recently, a study by Beckmann et al 7 showed that patella alta (mISI 1.8 vs. 1.6) is a risk factor for early failure for inlay PF resurfacing, but the same effect could not be shown in midterm follow‐up for onlay PF resurfacing 69 …”

“…Recently, a study by Beckmann et al 7 showed that patella alta (mISI 1.8 vs. 1.6) is a risk factor for early failure for inlay PF resurfacing, but the same effect could not be shown in midterm follow-up for onlay PF resurfacing. 69 Regarding the clinical outcome, more attention should be given to evaluating patella height as an important parameter for the outcome after TKA. The previous paradigm that patella baja causes problems and patella alta is unproblematic is not based on biomechanical data, which suggests the contrary.…”