Home > Knee Injury > Patella Tendon Adhesions and Patello-Femoral Dysfunction – Considerations Post-Knee Arthroscopy

Patella Tendon Adhesions and Patello-Femoral Dysfunction – Considerations Post-Knee Arthroscopy

Fernandez JW, Akbarshahi M, Crossley KM, Shelburne KB, Pandy MG.  Model predictions of increased knee joint loading in regions of thinner articular cartilage after patellar tendon adhesions.  J Orthop Res. 2011 Mar 7. doi: 10.1002/jor.21345. [Epub ahead of print]

http://www.ncbi.nlm.nih.gov/pubmed/21384421

Purpose & Rationale: There is a high prevalence of patello-femoral pain following ACL reconstruction and other knee arthroscopic surgeries.  Development of patello-femoral pain post ACL reconstruction or knee arthroscopy can lead to poor functional outcomes, decreased physical performance, and early onset knee osteoarthritis.  As such, it is important to understand biomechanical factors that can lead to the development of patello-femoral pain post ACL reconstruction / knee arthroscopy.  Understanding these biomechanical factors can guide clinical interventions to prevent this series of events from occurring.

Overview of Research Methods: The article by Fernandez et al. describes a complex mathematical model (finite element model) to investigate the effects of patella tendon adhesions on patello-femoral biomechanics.  The authors simulate 3 different patella tendon adhesion conditions: 1) No adhesion (normal functioning patella tendon), 2) Midpoint adhesion (patella tendon adhered to the tibia up to the midpoint between the tibial tuberosity and tibial plateau), and 3) Full adhesion (patella tendon adhered to the tibia the entire length from the tibial tuberosity to tibial plateau).

The following variables were assessed during a simulated walking task: Patella flexion angle (amount the inferior pole of patella was flexed toward the knee joint center), Inferior patella displacement, Anterior tibial translation, Patella tendon shear force, Contact area, Contact pressure, Contact location.

Key Findings:

  • Patella flexion angle and inferior patella displacement were increased in both the midpoint and full adhesion conditions
  • Anterior tibial translation was increased in both the midpoint and full adhesion conditions
  • Patella tendon shear force was increased in both the midpoint and full adhesion conditions
  • Patella contact area, pressure and location were also altered in the midpoint and full adhesion conditions.  Specifically, the contact pressures actually decreased in the adhesion conditions.  However, the contact location shifted more distally to regions of thinner cartilage.

Clinical Implications: Patella tendon adhesions significantly alter patella positioning (increased flexion and inferior dispalcement.  This leads to a distal shift in patella contact location to regions where articular cartilage is thinnest.  Although patella contact pressures are also slightly decreased the combination of shifting patella contact location to the thinnest articular cartilage regions is believed to have significant clinical implications.  Repetitive loading over these thin cartilage regions may lead to articular cartilage thinning and ultimately damage.  Thus, the alterations in patella biomechanics that occur with patella tendon adhesions may be an important factor influencing the high prevalence of patello-femoral pain in those who undergo ACL reconstruction or knee arthroscopy.

Preventing the development of patella tendon adhesions should be a primary goal of the post-surgical rehabilitation process.  This may be accomplished by working to maintain patella and patella tendon mobility through manual mobilization.  Failure to maintain proper patella / patella tendon mobility during post-surgical rehabilitation may increase the risk of patella tendon adhesions developing.

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Categories: Knee Injury
  1. Carl Eaton
    May 25, 2011 at 4:42 pm

    Dr. Padua,
    Is there any research indicating that tib-fem rotational mobility my be a probelem pre or post ACL injury? Thanks again for the site!

  2. May 25, 2011 at 11:04 pm

    Carl,
    There are several studies that have demonstrated people with ACL-reconstruction to have increased tibial internal rotation during a variety of functional tasks (e.g. gait, pivoting, stair climbing). It is not clear whether this is due to the inability of the ACL-graft to simulate the native ACL or due to a lack of neuromuscular control that results from the injury itself. Regardless of the mechanism the surgical ACL-reconstruction process does not restore normal tibial rotation.
    There is speculation that uncontrolled/excessive tibial rotation post ACL-injury (either in ACL-reconstructed or ACL-deficient) may be a causative factor for the increased risk of early onset osteoarthritis (OA) in these individuals. However, research has not yet determined if uncontrolled/excessive tibial rotation post ACL-injury actually does predispose people to early onset OA.
    Below are a few references that describe the resulting alterations in tibial rotation in an ACL-injured population. The review article by Stergiou et al is a nice summary of the literature in this area and also discusses the possible association with early onset OA.

    References:
    Stergiou N, Ristanis S, Moraiti C, Georgoulis AD. Tibial rotation in anterior cruciate ligament (ACL)-deficient and ACL-reconstructed knees: a theoretical proposition for the development of osteoarthritis.
    Sports Med. 2007;37(7):601-13.

    Chouliaras V, Ristanis S, Moraiti C, Tzimas V, Stergiou N, Georgoulis AD. Anterior cruciate ligament reconstruction with a quadrupled hamstrings tendon autograft does not restore tibial rotation to normative levels during landing from a jump and subsequent pivoting.J Sports Med Phys Fitness. 2009 Mar;49(1):64-70.

    Georgoulis AD, Ristanis S, Chouliaras V, Moraiti C, Stergiou N. Tibial rotation is not restored after ACL reconstruction with a hamstring graft. Clin Orthop Relat Res. 2007 Jan;454:89-94.

    Ristanis S, Stergiou N, Patras K, Vasiliadis HS, Giakas G, Georgoulis AD. Excessive tibial rotation during high-demand activities is not restored by anterior cruciate ligament reconstruction. Arthroscopy. 2005 Nov;21(11):1323-9.

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