Magnetic Resonance Imaging Characteristics of the Medial Patellofemoral Ligament Lesion in Acute Lateral Patellar Dislocations Considering Trochlear Dysplasia, Patella Alta, and Tibial Tuberosity–Trochlear Groove Distance

Balcarek, Peter; Ammon, Jan; Frosch, Stephan; Walde, Tim A.; Schüttrumpf, Jan P.; Ferlemann, Keno G.; Lill, Helmut; Stürmer, Klaus M.; Frosch, Karl-Heinz

doi:10.1016/j.arthro.2009.11.004

« Previous Next »Arthroscopy: The Journal of Arthroscopic and Related Surgery
Volume 26, Issue 7 , Pages 926-935, July 2010

Magnetic Resonance Imaging Characteristics of the Medial Patellofemoral Ligament Lesion in Acute Lateral Patellar Dislocations Considering Trochlear Dysplasia, Patella Alta, and Tibial Tuberosity–Trochlear Groove Distance

Peter Balcarek, M.D.
- Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine, Göttingen, Germany
- Arthroscopic Section, German Society of Trauma Surgery, Hannover, Germany
- Address correspondence and reprint requests to Peter Balcarek, M.D., Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine, Robert-Koch-Strasse 40, 37075 Göttingen, Germany
Jan Ammon, M.D.
- Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine, Göttingen, Germany
Stephan Frosch, M.D.
- Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine, Göttingen, Germany
- Arthroscopic Section, German Society of Trauma Surgery, Hannover, Germany
Tim A. Walde, M.D.
- Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine, Göttingen, Germany
- Arthroscopic Section, German Society of Trauma Surgery, Hannover, Germany
Jan P. Schüttrumpf, M.D.
- Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine, Göttingen, Germany
- Arthroscopic Section, German Society of Trauma Surgery, Hannover, Germany
Keno G. Ferlemann, M.D.
- Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine, Göttingen, Germany
Helmut Lill, M.D.
- Arthroscopic Section, German Society of Trauma Surgery, Hannover, Germany
- Department of Trauma and Reconstructive Surgery, Diakoniekrankenhaus Friederikenstift, Hannover, Germany
Klaus M. Stürmer, M.D.
- Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine, Göttingen, Germany
Karl-Heinz Frosch, M.D.
- Department of Trauma Surgery, Plastic and Reconstructive Surgery, University Medicine, Göttingen, Germany
- Arthroscopic Section, German Society of Trauma Surgery, Hannover, Germany

Received 3 May 2009; accepted 9 November 2009. published online 04 March 2010.

Purpose

The objective of this study was to analyze the injury patterns of the medial patellofemoral ligament (MPFL) in acute lateral patellar dislocations (LPDs) considering the anatomically relevant factors of patellar instability.

Methods

Knee magnetic resonance images were collected from 73 patients within 7 weeks after LPD, and the injury patterns of the MPFL were evaluated for trochlear dysplasia, for patellar height, and for the tibial tuberosity–trochlear groove (TT-TG) distance.

Results

Injury to the MPFL was found in 98.6% of the patients (72 of 73) after the acute LPD, with a complete tear in 51.4% (37 of 72), most frequently localized at the femoral attachment site, and a partial tear in 48.6% (35 of 72). Injury to the femoral origin (Fem), to the midsubstance (Mid), and to the patellar insertion (Pat) of the MPFL was found in 50.0% (36 of 72), 13.9% (10 of 72), and 13.9% (10 of 72), respectively. More than 1 site of injury was found in 22.2% (16 of 72), most frequently as a combined injury at the femoral origin and at the patellar insertion sites (Pat+Fem) (13 of 16). The study population, as well as the Pat, Fem, and Pat+Fem subgroups, showed significantly different values of trochlear dysplasia and patellar height when compared with the control group, whereas the data of the Mid group were not significantly different. In addition, injury at the patellar insertion (Pat) was accompanied by a significantly increased TT-TG distance when compared not only with the control group but also with the Fem, Mid, and Pat+Fem groups.

Conclusions

The data from our study indicate that patterns of MPFL injury depend on trochlear dysplasia, patellar height, and TT-TG distance. They show a new aspect in the complex interplay between active, passive, and static stabilizers of the patellofemoral joint.