Patellofemoral stress-testing device offers more accuracy, validity vs physical examination
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According to study results, the Porto Patellofemoral Testing Device is a valid tool for quantification of the patellofemoral position and displacement and had high intra-rater reliability. The instrumented stress-testing device compared with the physical examination also showed more accuracy, more precision and less variability.
Researchers assessed eight asymptomatic patients who underwent bilateral patellofemoral-instrumented examination with the Porto Patellofemoral Testing Device and MRI to evaluate the intra-rater reliability of the instrumented assessment method. They also assessed six patients with unilateral patellofemoral instability who underwent physical examination and testing with the device. Two blinded surgeons performed manual examination and compared it to measures with the device. Investigators also calculated ligament stiffness and compared the injured lower limbs and the non-injured lower limbs.
Results demonstrated the device had a pre-determined and reproducible stress-force application with “excellent” intra-rater agreement. Investigators noted the manual exam was not precise with regard to the variable examiner-dependent stress-force application. The device compared with the manual exam for patients who reached maximum translation force had a greater lateral patellar translation. The device was more accurate and precise with regard to the measurement of the patellar position and displacement compared with the visual estimation of the translated quadrants by manual exam. No relevant changes in patellar displacement after 62 N were seen in ligament stiffness curves. – by Monica Jaramillo
Disclosures: The researchers report no relevant financial disclosures.
Perspective
Back to TopPeter Jokl, MD
Patella instability has traditionally been assessed by physical examination with manual displacement of the patella at various levels of knee flexion. Much of the data recorded during these exams have been fraught with examiner variability and poor reproducibility.
The potential of having an instrumented device that produces accurate and reproducible measurement (data) would be a welcome addition to our ability to define treatment parameters (both nonsurgical and surgical) and substantiate outcome measures for this common condition.
This study indicates, that using a Porto Patellofemoral Testing Device that measures patella laxity, that displacement measurements were highly reproducible and superior to manual testing results. If these results hold up in similarly designed studies, is user friendly and reasonably priced, it would be a valuable tool for physicians treating patella femoral instability conditions.
Department of orthopedics and rehabilitation
New Haven, Connecticut
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