Medial abrasion syndrome: a neglected cause of persistent pain after knee arthroplasty

Introduction

Persistent post-operative pain (PPOP) has detracted from some otherwise successful knee arthroplasties. This study investigated medial abrasion syndrome (MAS) as a cause of PPOP after knee arthroplasty. The surgical techniques and outcomes of incorporating this concept into the management of both primary arthroplasty cases and patients suffering from unknown causes of PPOP after arthroplasties were presented.

Materials and methods

In a 1-year period, the author performed unicompartmental or total knee arthroplasty (the UKA or TKA group) that also eliminated medial abrasion phenomenon (MAP) on 196 knees of 150 patients at advanced stages of knee osteoarthritis (OA). During the same year, 16 knees of 16 patients with unknown causes of PPOP after knee arthroplasties were referred to the author for the arthroscopic medial release procedure (the AMR group) after being diagnosed as MAS. Subjective satisfaction, Knee Society Score (KSS), and Knee injury and Osteoarthritis Outcome Score (KOOS) evaluations were used for outcome study.

Results

All 166 patients were followed for more than 3 years (mean 3.7 years, 3.1–4.2) for the outcome study. All knees receiving arthroplasty showed medial plicae with MAP at the time of surgery. Only 2 of them suffered from PPOP: one was a neglected tibial plateau fracture with residual varus deformity after UKA, and the other was a late infection after TKA and received revision. The satisfactory rate was 98.8% in the UKA group, 99.1% in the TKA group, and 100% in the AMR group. The Knee Society Scores and all subscales of KOOS were statistically improved in all groups.

Conclusions

MAS is a cause of pain in patients who have received knee arthroplasties, and MAP should be eliminated to ensure a successful knee arthroplasty. PPOP after knee arthroplasty can be caused by MAS, which can be managed by AMR.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-020-02191-7.

Symptomatic medial synovial plica of the knee joint: an underestimated pathology in young patients

INTRODUCTION

To prospectively evaluate the outcome of arthroscopic resection of a symptomatic medial plica in patients under 30 years with evaluating the influence of sports, knee trauma and plica type.

METHODS

35 consecutive patients (38 knees), mean age 16.2 ± 4.7 years (9-26 years), 28 females (73.7%) were prospectively included. Patients with any additional surgical procedures or cartilage lesions > ICRS grade I were excluded. The influence of trauma to the knee, level of sport and the morphologic plica type on the outcome was evaluated in addition to standard knee scores before and 20.1 ± 9.3 months (12-44 months) after surgery.

RESULTS

The Knee Injury and Osteoarthritis Outcome Score improved significantly from 50.2 ± 19.1% (12.5-94.6) to 80.7 ± 15.3% (48.2-100; p < 0.001). The Tegner Activity Scale improved significantly from 2.2 ± 1.5 (0-6) to 4.9 ± 1.7 (3-10; p < 0.001) and the Kujala Anterior Knee Pain Scale improved significantly from 52.6 ± 16.6 (16-86) to 80.7 ± 16.5 (46-100; p < 0.001). The level of pain in the knee decreased from 7.9 ± 2.0 (1-10) to 3.1 ± 2.6 (0-9; p < 0.001) at follow-up on a numeric rating scale (0-10). Neither trauma to the knee, high impact sport, cartilage lesions to the medial femoral condyle nor the plica type or associated ICRS grade I cartilage lesion to the medial femoral condyle had a significant effect on the outcome parameters.

CONCLUSION

Arthroscopic resection of a symptomatic medial plica provides excellent clinical results in young patients. Trauma, high impact sports, ICRS grade I cartilage lesions to the medial femoral condyle or the plica type are not associated with a poorer outcome.

LEVEL OF EVIDENCE

Level IV, prospective case series with no control group.

Treatment of medial compartment knee osteoarthritis by arthroscopic 'L' medial release procedure

PURPOSE

To evaluate the clinical outcomes of an arthroscopic 'L' medial release (ALMR) procedure for the treatment of medial compartment knee osteoarthritis (MCKOA).

METHODS

Between January 2012 and December 2013, 372 patients with MCKOA of Kellgren's radiographic grade I-III were diagnosed. Among them, 252 patients with MCKOA received ALMR performed by a single surgeon. The other 120 patients received supportive treatment and were regarded as the control group. The Knee Society Score (KSS) at baseline and 2 years, and the subjective visual analogue scale (VAS) at baseline and 1st, 2nd, 6th, 12th, and 24th months were used for outcome studies.

RESULTS

There were 286 patients available for follow-up for more than 2 years and the mean follow-up period was 28 months. There were 202 patients with unilateral MCKOA in the ALMR group and 84 in the control group. The mean subjective VAS showed a statistically significant improvement after 6 months, and then remained relatively stable between the 6th and 24th month. The mean KSS for pain and function improved statistically at 2 years of follow-up.

CONCLUSIONS

This ALMR appears to be an effective and safe treatment for mild and moderate MCKOA.

Relationship between medial plica and medial femoral condyle--a three-dimensional dynamic finite element model

BACKGROUND

Many researches reported that the pathologic medial plica impinges on the facing medial femoral condyle during knee motion and leads to erosive changes of the articular cartilage. The purpose of this study was to construct a simplified three-dimensional dynamic finite element human knee model to evaluate the dynamics behaviour between different types of medial plicae with the facing medial femoral condyles during knee motion.

METHODS

A three-dimensional dynamic finite element model composed of femur, tibia, covering cartilage and medial plica was developed. The kinematics of this simulation model was verified by previous findings during arthroscopic examination. The validated model was used to investigate and compare the magnitudes of the cyclic pressures acting on the cartilage of the medial femoral condyles by three different types of medial plicae with various Young's moduli.

FINDINGS

All types of plicae remained in contact with the medial femoral condyles and shifted medially when the knees moved from extension to flexion. The contact pressures were positively correlated with the Young's moduli of the medial plicae. During the whole range of motion, the maximum contact pressures of all simulation scenarios occurred when the knees moved beyond 50° of flexion. When the Young's moduli of medial plicae were set greater than 60 MPa, all types of medial plicae would elicit contact pressures greater than 10 MPa on the medial femoral condyles.

INTERPRETATION

The close relationship and possible high contact pressure between fibrotic medial plica and medial femoral condyle during knee motion might be a cause of cartilage damage on the medial femoral condyle and warrants further investigation.