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Contact pressure at osteochondral donor sites in the patellofemoral joint
Ralph B Garretson1, Leonid I Katolik, Nikhil Verma
1Department of Orthopedic Surgery, University of Pennsylvania Hospitals, Philadelphia, PA, USA.
Background:
The lowest contact pressure point is presumed to be the best site to harvest an osteochondral plug and minimize morbidity.
Hypothesis:
Patellofemoral contact pressures are not uniform and are lowest along the medial patellofemoral articulation.
Study Design:
Controlled laboratory study.
Methods:
Seven cadaveric knees were tested with an electroresistive, dynamic pressure sensor placed onto the femoral side of the patellofemoral joint. The extensor mechanism was loaded with 89.1 N and 178.2 N, and the knee was manually cycled 3 times (0 degrees -105 degrees ) per load. Mean trochlear pressures were calculated.
Results:
Mean contact pressures were greatest in the central trochlea (5.80 kgf/cm(2)), followed by the lateral (2.56 kgf/cm(2)) and medial trochlea (1.60 kgf/cm(2)) at 89.1 N (P <.05). At 178.2 N, pressures increased to 9.47, 5.81, and 2.75 kgf/cm(2), respectively (P <.05). Lateral trochlear pressures decreased moving distally from 1.25 to 0.50 kgf/cm(2) at 89.1 N and 4.57 to 1.29 kgf/cm(2) at 178.2 N.
Conclusions:
Contact pressures are lowest along the medial trochlea and decrease distally along the lateral trochlea.
Clinical Relevance:
Osteochondral plugs from the medial femoral trochlea may be desirable if trochlear size permits. If harvesting from the lateral femoral trochlea, consider harvesting distally near the sulcus terminalis.
