Painful Pes Anserine Bursitis Following Total Knee Replacement Surgery: Two cases

Diagnostic ultrasound and ultrasound-guided injections for peri-articular pain after knee replacement

OBJECTIVE

The purpose of this technical report is to review the sonographic spectrum of abnormalities accounting for peri-articular pain after knee replacement surgery, as well as to demonstrate the clinical utility of ultrasound in the diagnosis and treatment of this subset of patients.

MATERIALS AND METHODS

Utilizing an imaging report database, we performed a search for ultrasound examinations performed by a single radiologist for knee pain after knee arthroplasty at our institution over a 10-year period. The search yielded 63 patients, whom we have categorized by causative pathology, with representative diagnostic and procedural ultrasound images selected for inclusion.

RESULTS

Our search yielded multiple causes of peri-articular knee pain after arthroplasty, including medial and lateral retinacular impingement and scarring, iliotibial band or conjoined tendon irritation, popliteus tendon impingement, medial collateral ligament impingement, pes anserine bursitis, and scarring of Hoffa's fat pad.

CONCLUSION

While knee arthroplasty is an often-successful procedure, it can be complicated by post-operative peri-articular knee pain. Ultrasound provides a valuable tool for the diagnosis of painful peri-articular knee pathology, as it allows for both static and dynamic evaluation, as well as direct correlation with patient symptoms, and is not confounded by the metal components. In addition to its diagnostic utility, ultrasound can also guide diagnostic and/or therapeutic injections of anesthetic and corticosteroid. Given these advantages, ultrasound is an important tool in managing the painful post-arthroplasty knee.

Pes anserinus pain syndrome following total knee arthroplasty for degenerative varus: incidence and predictors

PURPOSE

Pes anserinus pain syndrome (PAPS) is a well-described condition in the native knee; however, its incidence after total knee arthroplasty (TKA) is unknown. This study aimed to determine the incidence of PAPS after primary TKA, identify potential risk factors, and assess its response to treatment. Few case reports have been published until now; to our knowledge, ours is the first study assessing the incidence and predictors of post-TKA PAPS.

METHODS

A total of 389 primary TKAs performed for degenerative varus knee at a single institution by the same surgeon were analyzed. We recorded demographic variables, medical comorbidities, and clinical, radiographic, and surgical data. Specific predictors of interest were compared between post-TKA PAPS and controls.

RESULTS

The incidence was 5.6% (22/389). On univariate analysis, female sex (p = 0.03), body mass index (BMI) (41.3% ± 7.9; p < 0.001), and absence of pes anserinus release (p = 0.04) were significant predictors. On multivariable regression analysis, only BMI was a significant independent risk factor (p = 0.01). All patients were treated non-operatively; 81.8% responded to nonsteroidal anti-inflammatory drug-physical therapy program and 18.2% required an additional local steroid injection.

CONCLUSION

PAPS occurs after TKA; the incidence was found to be 5.6%. BMI seems to be an independent risk factor. It is a benign condition and can be effectively treated conservatively in most cases.