Diagnostic Value of MRI and Radiographs of the Knee to Identify Osteochondral Lesions in Acute Patellar Instability

Abstract

The purpose of this study was to define the diagnostic value of magnetic resonance imaging (MRI) and plain radiographs (X-ray [XR]) in identifying an osteochondral defect or loose body in patients undergoing operative treatment for patellar instability. A total of 87 patients treated operatively for patellar instability with medial patellofemoral ligament (MPFL) reconstruction between 2015 and 2019 were identified. Inclusion criteria were evidence of clinical patellar instability, preoperative XR and MRI studies, and concomitant diagnostic knee arthroscopy and MPFL reconstruction performed to address patellar instability. Patients were excluded if they had a history of prior procedure for patellar instability on the surgical knee, underwent MPFL reconstruction without concomitant diagnostic knee arthroscopy, or had an anterior cruciate ligament or posterior cruciate ligament deficient knee. Operative notes and arthroscopic images were reviewed to identify osteochondral or chondral injuries and loose bodies noted during diagnostic arthroscopy. The primary outcome was the identification of intra-articular loose bodies, chondral injury, or osteochondral defect on preoperative plain radiographs and MRI in patients with patellar instability. All MRIs were performed on a 3T MRI. The sensitivity and specificity of identifying loose bodies on MRI were 0.52 and 0.92 and on XR were 0.23 and 0.98, respectively. The sensitivity and specificity of identifying osteochondral lesions on MRI were 0.43 and 0.81 and on XR were 0.08 and 0.97, respectively. Of the 87 available reports, 45 (51%) described performing chondroplasty for Outerbridge grade II/III chondral lesions on diagnostic arthroscopy. In conclusion, MRI and XR are poorly sensitive at identifying loose bodies or osteochondral defects after patellar dislocations. The poor sensitivity of imaging studies must be considered when determining whether or not to recommend operative management to a patient with patellar instability. This is a Level IV, diagnostic study.

MRI as the optimal imaging modality for assessment and management of osteochondral fractures and loose bodies following traumatic patellar dislocation: a systematic review

“…Thirty‐eight articles [S.6a] qualified for inclusion of 1357 unique studies during the initial search conducted on February 26, 2021. Two studies [8, 15] qualified for inclusion upon a repeat search conducted on May 18, 2021 from 46 unique entries. No additional studies were identified and included through manually searching the references of the included studies.…”

“…MRI is often used to confirm the diagnosis and identify concomitant pathologies (71.1% of patients), such as osteochondral injuries and fractures [49], and provides a more comprehensive field of view and depiction of regional anatomy. A recent systematic review found higher sensitivity using MRI compared to plain radiography for the detection of both loose bodies (0.52 vs 0.23) and osteochondral lesions (0.43 vs 0.08) with comparable specificity (0.92 vs 0.98 and 0.81 vs 0.97, respectively) [8]. A prospective case control study suggested using MRI in anyone who suffers a patellar dislocation as OCF should always be suspected until proven otherwise [57].…”

“…Regarding resolution of these OCF, there lacks a consensus on the optimal approach and the decision ultimately comes down to fragment size and quality. For larger fragments (> 1 cm 2 [3, 28, 54], > 0.5 cm 2 [8], 1–3 mm [51], and 4–18 mm [16]) with enough donor site surface area, surgical fixation to bone with headless variable pitch screws [32] or the transpatellar suture technique [35] was the option of choice. For smaller, poor‐quality fragments or those with a long lag‐time before intervention, excision was preferred [S.6r].…”

Magnetic resonance imaging is able to detect patellofemoral focal cartilage injuries: a systematic review with meta-analysis

“…Therefore, correctly identifying the location and extent of cartilage defects will play a crucial role during the treatment planning. 1 3 Magnetic resonance imaging (MRI) plays a major role in the early diagnosis of PF joint disorders [1,6,9,22,33,51,59]. Cartilage injuries are often present and it is thus a cornerstone to know how reliable and accurate it is for detecting and grading PF cartilage defects.…”

“…Magnetic resonance imaging (MRI) plays a major role in the early diagnosis of PF joint disorders [1, 6, 9, 22, 33, 51, 59]. Cartilage injuries are often present and it is thus a cornerstone to know how reliable and accurate it is for detecting and grading PF cartilage defects.…”