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Fewer ligament reconstruction failures with hinged external fixation for knee dislocations

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Fewer ligament reconstruction failures with hinged external fixation for knee dislocations

Vol: 3| Issue: 5| Number:10| ISSN#: 2564-2537
Study Type:Therapy
OE Level Evidence:2
Journal Level of Evidence:1

Hinged external fixation in the treatment of knee dislocations: a prospective randomized study

J Bone Joint Surg Am. 2014 Feb 5;96(3):184-91. doi: 10.2106/JBJS.L.01603.

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100 patients with a total of 103 knee dislocations were randomized to receive either a hinged knee brace or external fixation with a Compass Knee Hinge as part of a postoperative rehabilitation protocol. This study aimed to determine whether an external fixator would provide equivalent knee range of motion and improve failure rate in comparison to a hinged knee brace up to at least 1 year postoperatively. Results revealed significantly lower individual ligament reconstruction failure rates with the Compass Knee Hinge compared to hinged knee brace use. Lower knee reconstruction failure rates were also associated with the external fixator, but statistical significance was not achieved. Clinical outcome and knee range of motion statistics were similar between groups.

Publication Funding Details +
Industry funded
Smith & Nephew
None disclosed

Risk of Bias


Reporting Criteria


Fragility Index


Was the allocation sequence adequately generated?

Was allocation adequately concealed?

Blinding Treatment Providers: Was knowledge of the allocated interventions adequately prevented?

Blinding Outcome Assessors: Was knowledge of the allocated interventions adequately prevented?

Blinding Patients: Was knowledge of the allocated interventions adequately prevented?

Was loss to follow-up (missing outcome data) infrequent?

Are reports of the study free of suggestion of selective outcome reporting?

Were outcomes objective, patient-important and assessed in a manner to limit bias (ie. duplicate assessors, Independent assessors)?

Was the sample size sufficiently large to assure a balance of prognosis and sufficiently large number of outcome events?

Was investigator expertise/experience with both treatment and control techniques likely the same (ie.were criteria for surgeon participation/expertise provided)?

Yes = 1

Uncertain = 0.5

Not Relevant = 0

No = 0

The Reporting Criteria Assessment evaluates the transparency with which authors report the methodological and trial characteristics of the trial within the publication. The assessment is divided into five categories which are presented below.




Outcome Measurements


Inclusion / Exclusion


Therapy Description



Detsky AS, Naylor CD, O'Rourke K, McGeer AJ, L'Abbé KA. J Clin Epidemiol. 1992;45:255-65

The Fragility Index is a tool that aids in the interpretation of significant findings, providing a measure of strength for a result. The Fragility Index represents the number of consecutive events that need to be added to a dichotomous outcome to make the finding no longer significant. A small number represents a weaker finding and a large number represents a stronger finding.

Why was this study needed now?

Knee dislocation can result in multiple-ligament injuries and are commonly caused from blunt trauma. Rehabilitation protocols have typically been focused on achieving and maintaining ligamentous stability following surgery. However, it has been suggested that such postoperative practices may compromise the long-term clinical outcome and increase the risk of arthrofibrosis, and that early aggressive protocols may be more beneficial. As such, the Compass Universal Hinge external fixator, initially developed for the elbow, was modified for the knee (Compass Knee Hinge) to accommodate these protocols, allowing early motion without increased stress. Thus, this study aimed to determine the efficacy of this device.

What was the principal research question?

Does a Compass Knee Hinge external fixator provide comparable knee range of motion and result in fewer failures when compared to a control external hinge brace following ligament reconstruction after a minimum of 12 months?

Study Characteristics -
100 patients with 103 knee dislocations (injuries to anterior cruciate ligament [ACL], and posterior cruciate ligament [PCL], posterolateral corner, and/or posteromedial corner) were randomized. Staged ligament reconstruction for the PCL, posterolateral corner, and posteromedial corner were performed 3-4 weeks following dislocation and ACL reconstructions were performed 6 weeks after initial surgery. Progressive postoperative protocols were followed in both groups. Patients received continuous passive motion machines and performed weight bearing as tolerated with the knee extended. Additionally, knee motion was progressively increased along with quadriceps and hamstring strengthening protocols.
Compass Knee Hinge: At the index surgery, patients received placement of the Compass Knee Hinge. Fluoroscopy was first performed to locate the isometric point on the femur for placement of a centering wire. The hinge was then fixed using femoral and tibial external fixation pins with Rancho Cubes.. In the event of surgery involving repair or reconstruction of the posteromedial and/or posterolateral corner, the centering wire was placed prior to the repair or reconstruction. The hinge was mounted and femoral external fixation pins placed through the Rancho Cubes. The hinge was then detached until repair/reconstruction was completed, after which it was placed back on, and fixed with tibial pins. The device was kept on the knee until the scheduled ACL reconstruction (i.e. 6 weeks after). (n=45 with 47 dislocations)
Hinged knee brace: Patients were fitted with a hinged knee brace following operation. (n=55 with 56 dislocations)
Outcomes included knee motion, stability (0 no laxity, 1+: 1-5mm, 2+: 6-10mm, and 3+: >10mm), and visual analog scale pain score. A stable and clinically successful knee was defined as 0 or 1+ laxity during clinical examination, whereas a failure was defined as 2+ or 3+ laxity. For ACL and PCL, a failure was defined as a side-to-side difference of >3mm using a KT-2000 arthrometer (mm). Return to employment/recreational activity, Lysholm, International Knee Documentation Comittee (IKDC) objective and subjective scores, Short form-36 (SF-36), and condition of soft tissue surrounding the knee (per Tscherne and Gustilo score) were also recorded.
RCT, Prospective
Follow-ups were conducted at 2, 6, 12, 26, and 52 weeks for the first year, and then once annually thereafter.

What were the important findings?

  • 9 of 32 (28%) reconstructions failed with the control hinge knee brace versus 7 of 47 (15%) with the Compass Knee Hinge, a nonsignificant difference (p=0.15).
  • A significantly larger percentage of individual ligament reconstruction failed with the control hinge knee brace (22/105 [21%]) compared to the Compass Knee Hinge (11/157 [7%]) (p<0.001).
  • Mean Lysholm scores were similar between groups, with scores of 87.7 (range: 61-100) and 87.2 (69-100) in the control hinge knee brace and Compass Knee Hinge groups, respectively, up to 1 year postoperatively, and 90.1 and 89.9, respectively, up to 2 years postoperatively.
  • IKDC subjective scores did not significantly differ between the control hinge knee brace and Compass Knee Hinge groups at 24 months; mean scores were 56.8 and 49.5, respectively. Acceptable IKDC objective scores (normal and nearly normal knees) were achieved in 75% and 81% of the groups, respectively.
  • Mean VAS pain scores were similarly low between groups; 2.5 (range: 0-7) vs. 2.8 (0-8) for control hinge knee brace and Compass Knee Hinge, respectively.
  • 82% of control hinge knee brace patients returned to work at full duty, 9% at light duty, and 9% did not return by final follow-up. In the Compass Knee Hinge group, these values were 73%, 9%, and 18%.
  • Overall, knee range of motion was good in both groups at the final evaluation. Mean range of motion was from 1 to 132 deg in the control group, and 2 to 124 deg in the Compass Knee Hinge group.

What should I remember most?

Patients who received a Compass Knee Hinge had a significantly lower individual ligament reconstruction failure rate compared to those who received an control hinge knee brace. Lysholm scores, IKDC subjective and objective scores, VAS pain scores, knee range of motion, and percentage of patients returning to work were similar between groups.

How will this affect the care of my patients?

The results indicated that progressive rehabilitation protocols can be achieved using a Compass Knee Hinge external fixator without compromising knee stability following knee reconstruction surgery. However, this device is expensive and takes time to apply, evoking a high learning curve and prolonging operation time. Future studies are warranted in larger populations to further investigate the efficacy of the Compass Knee Hinge.

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