Irreducible Knee Dislocation Associated With a Tertiary Gastrocnemius Head: A Case Report

A systematic review on management and outcome of irreducible knee dislocations

BACKGROUND

Irreducible knee dislocations (IKD) are rare and can often be missed or misdiagnosed. The incidence of knee dislocation is quoted between 0.01% and 0.2% of all orthopaedic injuries, with up to 4% of these dislocations sub-classified as irreducible. The primary aim of this systematic review was to analyse cases of IKD described in the literature, with a secondary aim of producing a streamlined approach for managing these patients.

PATIENTS AND METHODS

A systematic review of the literature was conducted on 1st September 2021 in accordance with the PRISMA guidelines using the online databases Medline and EMBASE. The review was registered prospectively in the PROSPERO database. Case reports or clinical studies or reporting on IKD were included. The studies were appraised using the Methodological Index for Non-Randomized Studies (MINORS) tool and Newcastle-Ottawa quality assessment scale.

RESULTS

The search strategy identified 60 studies eligible for inclusion, giving a total of 114 cases of IKD. Posterolateral dislocation was most common, seen in 85% of cases. The dimple sign was present in 70%. All cases required surgical intervention to achieve joint reduction. The most commonly involved structure blocking reduction was the medial collateral ligament (MCL)±medial structures, seen in 52.4%. MCL reconstruction or repair was carried out in 32.3% cases. The overall incidence of neurovascular injury was 9% and the overall complication rate was 14.4%.

CONCLUSION

Based on the findings of this SR we conclude that: the most common type of IKDs are PL dislocations, and the MCL, medial retinaculum and capsule and vastus medialis oblique form the most common structures involved in block to reduction and often will require open reduction and repair in acute setting if arthroscopic reduction fails. The most common pattern of injury to ligament is likely to be ACL, PCL, MCL±other structures but the MCL will be the most commonly repaired ligament. The dimple sign is often present and is highly pathognomonic of IKD. The incidence of neurovascular injury is uncommon. The most common post-operative complications likely to be encountered is medial skin necrosis and postoperative knee stiffness. Therefore, patients should be mobilised as early as possible with ROM in hinge brace.

LEVEL OF EVIDENCE

IV.

The Efficacy and Outcome of a Two-Staged Operation for Irreducible Knee Dislocation: A Prospective Short-Term Follow-Up

Background: Irreducible knee dislocation (IKD) is a very rare but serious type of knee dislocation; it can lead to soft tissue necrosis due to incarceration of the medial structures and faces great difficulty in the postoperative rehabilitation, too. IKD needs careful pre-operative planning. There is no universal agreement about the appropriate surgical strategy for IKD. The purpose of this study was to investigate the clinical efficacy, safety, and outcome of the two-staged operation in treatment of IKD. Methods: IKD patients were included from June 1, 2016 to May 31, 2020. In the stage-1 surgery, acute reduction and extra-articular structure repair were performed. Following an intermediate rehabilitation, delayed cruciate ligament reconstructions were performed in stage-2. Physical examination, CT, MRI, and X-ray were performed during the pre-operative period. Knee function, joint stability, ligament laxity, knee range of motion (ROM), and alignment were accessed at follow-ups. The minimum and maximum follow-up times were 0.5 years and 1 year, respectively. Results: In total, 17 IKD patients were included. There were three subjects (17.65%) missing at the 1 year follow-up and the average follow-up was 11.18 ± 2.53 months. After stage-1, normal alignment and superior valgus/varus stability were restored in most subjects; however, a notable anterior-posterior instability still existed in most patients. The intermediate rehabilitation processed smoothly (6.94 ± 1.20 weeks), and all patients achieved knee ROM of 0-120° finally. At 0.5 years and 1 year follow-up after stage-2, all subjects had achieved normal knee stability, ROM, and satisfying joint function. No infection or DVT was observed. Conclusions: The two-staged operation for IKD has superior efficacy on knee stability and function, and it can facilitate the rehabilitation and achieve satisfactory short-term outcome.

The Effect of Irreducible Dislocation on Functional Outcomes in Knees With Multiligament Injuries: A Matched-Cohort Analysis

Background:

Most cases of bicruciate knee dislocation (KD) with associated posteromedial disruption (KD-IIIM) are reducible, but some cannot be reduced by closed reduction because of soft tissue incarceration.

Purpose:

To compare the clinical characteristics and functional outcomes of KD-IIIM injuries in patients with or without incarceration of soft tissue requiring open or arthroscopic reduction.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

This retrospective cohort study of patients with KD was conducted between January 2013 and December 2017 at a single large institution. We applied a 1:2 matching ratio between patients with irreducible KD-IIIM injuries (irreducible group; n = 14) and those with reducible KD-IIIM injuries (control group; n = 28). There were 13 patients in the irreducible group and 25 in the control group who completed follow-up (≥2 years) and were included in our analysis. The efficacy of treatment in patients with KD was evaluated based on range of motion, the Tegner score, the Lysholm score, and the International Knee Documentation Committee (IKDC) score.

Results:

At the end of follow-up, the mean Tegner score was 4.5 (range, 4-6), the mean Lysholm score was 79.2 (range, 60-95), and the mean IKDC score was 78.6 (range, 60.9-95.4) in the irreducible group. The respective results in the control group were 4.6 (range, 3-8), 83.1 (range, 39-100), and 80.6 (range, 42.5-96.6). These scores did not differ significantly between the 2 groups. Similarly, mean range of motion was similar between groups (irreducible, 118.1°; control, 124.8°). In the irreducible group, the acute subgroup showed significantly higher Lysholm and IKDC scores than the chronic subgroup, while the acute and chronic subgroups in the control group showed no significant differences in these respective outcome scores.

Conclusion:

In the present study, the treatment of irreducible KD led to similar functional outcomes compared with reducible KD. However, the treatment of chronic irreducible KD led to worse outcomes compared with acute irreducible KD, and therefore, urgent reduction is recommended in these patients.