Summary

Natural history of patellofemoral pain with and without predisposing factors, and without treatment, at a long term follow up

Abstract

Introduction

Patellofemoral pain is a common symptom, elicited by joint malalignment and/or by a deficiency in one of the joint stabilizers, representing different etiologies usually included under the term of “patellofemoral syndrome”. Some anatomical factors are considered predisposing, used to classify a patient into 3 subgroups, as proposed by Dejour: Objective Patellar Instability (OPI), Potential Patellar Instability (PPI), and Patellofemoral Pain Syndrome (PFPS); while many evidences were published about OPI and its treatments, less is known about the progression of PPI into OPI, and about natural history of PFPS.

Purpose

of this paper was to critically analyze the outcomes of patients suffering by patellofemoral pain, that didn’t underwent surgery, and at long-term follow-up, in terms of symptoms progression, CT evidences, Kujala and Tegner score.

Methods

Study design is prospective and longitudinal, in accordance with a study protocol set since 2002. Patients from the whole region with anterior knee pain were referred to our center and screened before continuing the therapeutic process with their physicians; all patients underwent a Lyonnese CT scan. Patients with a history of a traumatic injury, dislocations, and subluxations were excluded; demographics, clinical data, CT measurements, Kujala and Tegner scores were recorder at this point. After one and ten years, new examination was performed. Patients that underwent surgery were excluded, data about type of surgery and time from recruitment to surgery was noted. Only patients suffering from PFPS and PPI formed the final population: symptoms progression, CT scans modifications, Kujala and Tegner scores, and the need for recurrent NSAID’s therapy, rehabilitation and intrarticular therapy were analyzed.

Results

In total, 148 patients were recruited, and final population was made of 92 patients (mean age: 25 years, mean BMI: 22.7), divided in 71 cases of PFPS and 21 cases of PPI. Excluded patients, n=56, underwent surgery in between the follow-ups: 18 patients with PFPS and 38 with PPI, all after a mean 14 months from recruitment. After ten years, patients with PFPS showed significant (p<0,005) pain reduction, occurrence of articular blocks, stiffness, and subjective instability, and a significant (p<0,005) increase in metereopathic nuisance, use of NSAIDS, and need for physical rehabilitation; Tegner score demonstrated a mean reduction of 1 level of activities, and Kujala showed a little functional improvement increasing from 72,2 to 82,5. PPI group showed similar results with a higher occurrence, and need for physical rehabilitation; moreover, the magnitude of increase in Kujala score was higher compared to the PFPS group. The occurrence of documented dislocation in the 16% of the cases. CT analysis did not revealed modifications at the final follow-up.

Conclusions

The paper describes the natural history of untreated patellofemoral pain with or without predisposing factors for instability. Patients tend adapt to the patellofemoral condition through a limitation of the activities, cyclic use NSAIDS and rehabilitation, suffering from less pain described as a metereopathic nuisance, and in some cases suffering from subjective instability. Our data also showed good functional recovery, therefore advising for a more cautious attitude about PFPS, PPI, and surgical indications.