Summary
This study examined long-term outcomes in patients who experienced postoperative septic knee arthritis after anterior cruciate ligament (ACL) reconstruction, finding that even after successful infection treatment and graft preservation, these patients developed significantly more osteoarthritis and had a restricted range of motion compared to a noninfected group.
Abstract
Background
Postoperative septic knee arthritis is a feared complication following anterior cruciate ligament (ACL) reconstruction. In previous studies evaluating short-term and mid-term follow-up, good knee function has been described, however long-term consequences have not been investigated. Therefore, purpose of this study was to evaluate knee joint function, activity level, and osteoarthritis development in patients at least 8 years after postoperative septic knee arthritis following ACL reconstruction and to compare to a matched control group including patients after ACL reconstruction without any signs of septic knee arthritis.
Methods
From May 2010 to January 2012, 39 patients in our institution were treated with septic knee arthritis following ACL reconstruction with graft-retaining treatment protocols. Follow-up examinations after a minimum of 8 years included clinical examination, measurement of anterior translation (Rolimeter), IKDC, WOMAC, and Tegner-Score. Progression of osteoarthritis was described in radiographs using Kellgren-Lawrence-Score. Aspiration of synovial fluid was performed in patients with signs of persistent infection. Aspirated synovial fluid was evaluated macroscopically, microbiologically, and by multiplex PCR. Based on concomitant injuries, ACL graft, and preoperative Tegner Score (± 1), a 1:1 case-control matching group including patients ACL reconstruction without any signs of postoperative septic knee arthritis was assembled and examined in the same manner.
Results
20 patients with septic knee arthritis (51%) could be included after a mean follow-up period of 8.6yrs [8.0-9.8]. The control group included 20 patients (FU 10.0yr, [9.7-10.3]).
There were no significant side-to-side differences regarding Lachman Test (2.8 mm ± 1.7 mm vs. 2.3 mm ± 2.3mm; p=0,052). In the Infection Group, a significantly higher number of patients with extension deficite (7.8°±5,1°) (p=0.02) was noted. In both groups the mean Tegner-Score of 6.75 [3-10] and 6.85 [3-10], was significantly reduced (p<0.05) compared to the preoperative Score, however no significant difference in degree of reduction was noted (-2.1(± 2.7) vs. -1.1(±1.9) p=0.218). At =8 years follow up there was no significant difference regarding IKDC (p=0,409) and WOMAC-Score (p=0.621). A significantly higher grade of osteoarthritis was found in the infection group (1.7±0.8) compared to the control group (0.8±1.5) (p=0.021).
In three patients, there were clinical signs of persistent knee infection. Neither the microbiological examination nor the PCR of the joint puncture revealed persistent septic knee arthritis in any of these patients.
Discussion
Patients with postoperative septic knee arthritis following ACL reconstruction develop significantly more osteoarthritis and restricted range of motion even after successful rehabilitation of the infection and graft preservation compared to a matched noninfected group.