The Hip-Spine Effect: A Biomechanical Study of Ischiofemoral Impingement Effect on Lumbar Facet Joints.
OBJECTIVE
To assess the relation between ischiofemoral impingement (IFI) and lumbar facet joint load during hip extension in cadavers.


METHODS
Twelve hips in 6 fresh T1-to-toes cadaveric specimens were tested. A complete pretesting imaging evaluation was performed using computed tomography scan. Cadavers were positioned in lateral decubitus and fixed to a dissection table. Both legs were placed on a frame in a simulated walking position. Through a posterior lumbar spine approach L3-4 and L4-5 facet joints were dissected bilaterally. In addition, through a posterolateral approach to the hip, the space between the ischium and the lesser trochanter was dissected and measured. Ultrasensitive, and previously validated, piezoresistive force sensors were placed in lumbar facet joints of L3-4 and L4-5. Lumbar facet loads during hip extension were measured in native hip conditions and after simulating IFI by performing lesser trochanter osteotomy and lengthening. Four paired t-tests were performed comparing normal and simulated IFI on the L3-L4 and L4-L5 facet joint loads.


RESULTS
After simulating IFI, mean absolute differences of facet joint load were 10.8 N (standard error of the mean [SEM] ±4.53, P = .036) for L3-4 at 10° of hip extension, 13.71 N (SEM ±4.53, P = .012) for L3-4 at 20° of hip extension, 11.49 N (SEM ±4.33, P = .024) for L4-5 at 10° of hip extension, and 6.67 N (SEM ±5.43, P = .245) for L4-5 at 20° of hip extension. A statistically significant increase in L3-4 and L4-5 lumbar facet joint loads of 30.81% was found in the IFI state as compared with the native state during terminal hip extension.


CONCLUSIONS
Limited terminal hip extension due to simulated IFI significantly increases L3-4 and L4-5 lumbar facet joint load when compared with non-IFI native hips.


CONCLUSIONS
This biomechanical study directly links IFI to increased lumbar facet loads and supports the clinical findings of IFI causing lumbar pathology. Assessing and treating (open or endoscopic) hip disorders that limit extension could have benefit in patients with concomitant lower back symptoms.
Hip Preservation Center, Baylor University Medical Center at Dallas, Dallas, Texas, U.S.A.; Orthopedic Unit, Clínica Las Américas, Medellín, Colombia; School of Medicine, Universidad de Antioquia, Medellín, Colombia. Electronic address: juangomezhoyos@gmail.com.
Juan
J
Gómez-Hoyos
Department of Bioengineering, University of Texas at Arlington, Arlington, Texas, U.S.A.
Anthony
A
Khoury
Hip Preservation Center, Baylor University Medical Center at Dallas, Dallas, Texas, U.S.A.
Ricardo
R
Schröder
College of Medicine, University of Oklahoma, Oklahoma City, Oklahoma, U.S.A.
Eric
E
Johnson
Hip Preservation Center, Baylor University Medical Center at Dallas, Dallas, Texas, U.S.A.
Ian J
IJ
Palmer
Hip Preservation Center, Baylor University Medical Center at Dallas, Dallas, Texas, U.S.A.
Hal D
HD
Martin
D000368:Aged; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D057925:Femoracetabular Impingement / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed; D021801:Zygapophyseal Joint / Q000000981:diagnostic imaging / Q000503:physiopathology*