Related Experiment Video
Updated: Jan 12, 2026
Diagnosis of Musculus Gastrocnemius Tightness - Key Factors for the Clinical Examination
Published on: July 7, 2016
Diagnosing Flexion Laxity After Knee Arthroplasty Using the "Hanging" Clunk Test and the Standard-To-Hanging Lateral
Thomas J Blumenfeld1, William L Bargar1, Derek F Amanatullah2
1UC Davis, Sutter Medical Center, Sacramento, California.
Background:
Flexion laxity after total knee arthroplasty (TKA) may be difficult to diagnose. We describe simple clinical and radiographic tests that may aid in the identification of this problem.
Methods:
There were 99 consecutive nonselected patients who had 128 TKAs presenting to our clinic for scheduled or unscheduled follow-up at a minimum of one year postprocedure, who were enrolled in an institutional review board-approved study. Patients were divided into two groups (cases = self-report of pain, controls = no pain). All patients underwent routine clinical and radiographic evaluation, as well as physical examination for a hanging clunk sign, and one additional radiographic examination (hanging lateral radiograph).
Results:
For the cases group (n = 51), a positive hanging clunk sign was identified in six patients. Clinical flexion laxity was identified in two patients. For the control group (n = 76), a positive hanging clunk sign was identified in 15 patients. Clinical flexion laxity was identified in three patients. At a standard-to-hanging lateral difference ≥ four mm, 11 patients complained of pain, and seven did not (61%, specificity: 91%, sensitivity: 23%, accuracy: 64%). The overall incidence of a positive hanging clunk sign was 16.5%.
Conclusion:
Isolated flexion laxity may be difficult to diagnose. Flexion laxity after TKA may be difficult to diagnose. The clinical complaint of pain correlated with a radiographic flexion gap difference of four mm or greater. The hanging lateral radiograph may assist in identifying isolated flexion laxity after TKA.
Level Of Evidence:
Level II diagnostic study.
