Needle Arthroscopy Demonstrates High Sensitivity and Specificity for Diagnosing Intra-Articular Shoulder and Knee Pathology.

Introduction:  Needle arthroscopy has been introduced in recent years as an alternative to magnetic resonance imaging (MRI) for the evaluation of knee and shoulder conditions. It has continued to evolve at a rapid rate with newer generation models making in-office integration simple. As MRI can sometimes prove inconclusive, it is worthwhile to consider these alternative options for evaluating musculoskeletal pathology as a primary diagnostic tool.  Purpose: The purpose of this study is to evaluate the specificity and sensitivity of needle arthroscopy in diagnosing intra-articular shoulder and knee pathology in a small case series of patients who ultimately underwent surgical arthroscopy.

Methods: A retrospective, single-centre, single-surgeon, cohort study was performed over a three-year period from August 2018 to June 2021. During this time, diagnostic needle arthroscopy was performed on patients with suspected shoulder or knee pathology based on MRI findings and clinical exams. These patients subsequently underwent standard surgical arthroscopy.

Results: Thirty-four patients were included in the study. There were 35 joints included, 25 shoulders and 10 knees, with a mean age of 41.88 +/- 11.32 years and BMI of 29.33 +/- 6.27 in the shoulder group and a mean age of 45.5 +/- 14.54 and BMI of 31.5 +/- 4.94 in the knee group. When evaluating shoulder pathologies, needle arthroscopy showed a sensitivity of 0.93 for rotator cuff tears, 1.00 for labral tears and 1.00 for loose bodies. Needle arthroscopy for the shoulder was found to be 100% specific for all shoulder pathologies. Needle arthroscopy for the knee was found to have a 1.00 sensitivity for detecting chondral defects and 0.80 sensitivity for meniscal tears. There were once again no false positive needle arthroscopy findings amongst the knee group.

Conclusion: Needle arthroscopy is an accurate diagnostic tool for the evaluation of intra-articular knee and shoulder musculoskeletal pathology. It can provide a potential solution for MRI-derived diagnostic inaccuracies that can lead to missed pathologies or unindicated procedures. It is less invasive than surgical arthroscopy and should be considered a useful tool in the armamentarium of orthopedic surgeons.