Preoperative patellofemoral anatomy affects failure rate after isolated patellofemoral inlay arthroplasty

Purpose To analyze whether preoperative patellofemoral anatomy is associated with clinical improvement and failure rate after isolated patellofemoral arthroplasty (PFA) using a modern inlay-type trochlear implant. Methods Prospectively collected 24 months data of patients treated with isolated inlay PFA (HemiCAP® Wave, Arthrosurface, Franklin, MA, USA) between 2009 and 2016, and available digitalized preoperative imaging (plain radiographs in three planes and MRI) were retrospectively analyzed. All patients were evaluated using the WOMAC score, Lysholm score, and VAS pain. Patients revised to TKA or not achieving the minimal clinically important difference (MCID) for the total WOMAC score or VAS pain were considered failures. Preoperative imaging was analyzed regarding the following aspects: Tibiofemoral OA, patellofemoral OA, trochlear dysplasia (Dejour classification), patellar height (Insall–Salvati index [ISI]; Patellotrochlear index [PTI]), and position of the tibial tuberosity (TT–TG and TT–PCL distance). Results A total of 41 patients (61% female) with a mean age of 48 ± 13 years could be included. Fifteen patients (37%) were considered failures, with 5 patients (12%) revised to TKA and 10 patients (24%) not achieving MCID for WOMAC total or VAS pain. Failures had a significantly higher ISI, and a significantly lower PTI. Furthermore, the proportion of patients with a pathologic ISI (> 1.2), a pathologic PTI (< 0.28), and without trochlear dysplasia were significantly higher in failures. Significantly greater improvements in clinical outcome scores were observed in patients with a higher preoperative grade of patellofemoral OA, ISI ≤ 1.2, PTI ≥ 0.28, TT–PCL distance ≤ 21 mm, and a dysplastic trochlea. Conclusion Preoperative patellofemoral anatomy is significantly associated with clinical improvement and failure rate after isolated inlay PFA. Less improvement and a higher failure rate must be expected in patients with patella alta (ISI > 1.2 and PTI < 0.28), absence of trochlear dysplasia, and a lateralized position of the tibial tuberosity (TT–PCL distance > 21 mm). Concomitant procedures such as tibial tuberosity transfer may, therefore, be considered in such patients. Level of evidence Level III, retrospective analysis of prospectively collected data.

Clinical results in reconstruction of medial patellofemoral ligament

Background: The reconstruction of the medial patellofemoral ligament (MPFL) is the most suitable treatment for the patellar instability at the present in patients with two or more episodes of dislocation or only one with condral lesion. This is because it is the principal medial stabilizer of the patella. This process could be supplemented with an osseous correction as tibial tuberosity transference. Objectives: assess the clinical results of the reconstruction of the MPLF in patients with patellar instability. Study Design: Case series, level of evidence IV. Methods: We enroll all patients with this procedure between form April 2011 to February 2015, the sample has 27 reconstruction in 25 patients, who has two or more episodes of patellar dislocation. The graft used was gracilis tendon, set with suture anchor, and tibial tuberosity transfer in 9 patients who need an osseous procedure. Results: The average Kujala score was 90,1 points ( 64-100). Was necessary tibial tuberosity transference in one third of se sample. And in those patients there no difference compared with the isolated reconstruction.There was no episode of patellar dislocation or a second surgical time in the sample. Conclusion: The reconstruction of MPLF show excellent clinical outcomes in a short and medium terms , with 0% of dislocation and no second surgical time, in this kind of patients.