Sagittal plane tilting deformity of the patellofemoral joint: a new concept in patients with chondromalacia patella
The aims of this study were to evaluate sagittal plane alignment in patients with chondromalacia patella via magnetic resonance imaging (MRI), analyse the relationships between the location of the patellar cartilaginous lesions and sagittal alignment and finally investigate the relationships between the sagittal plane malalignment and patellofemoral loadings using by finite element analysis.
Fifty-one patients who were diagnosed with isolated modified Outerbridge grade 3–4 patellar chondromalacia based on MRI evaluation and 51 control subjects were evaluated. Chondromalacia patella patients were divided into three subgroups according to the chondral lesion location as superior, middle and inferior. The patella–patellar tendon angle (P–PT) was used for evaluation of sagittal alignment of patellofemoral joint. Each subgroup was compared with control group by using P–PT angle. To investigate the biomechanical effects of sagittal plane malpositioning on patellofemoral joint, bone models were created at 30°, 60° and 90° knee flexion by using mean P–PT angles, which obtained from patients with chondromalacia patellae and control subjects. The total loading and contact area values of the patellofemoral joints were investigated by finite element analysis.
The mean age of all participants was 52.9 ± 8.2 years. The mean P–PT angle was significantly lower in chondromalacia group (142.1° ± 3.6°) compared to control group (144.5° ± 5.3°) (p = 0.008). Chondral lesions were located in superior, middle and inferior zones in 16, 20 and 15 patients, respectively. The mean P–PT angles in patients with superior (141.8 ± 2.7) and inferior subgroups (139.2 ± 2.3) were significantly lower than the values in the control group (p < 0.05). The contact area values were detected higher in models with chondromalacia than in the control models at the same flexion degrees. There were increased loadings at 30° and 90° flexions in the sagittal patellar tilt models.
This study revealed that sagittal plain malpositioning of the patellofemoral joint might be related to chondromalacia, especially in the presence of lesions in the upper and lower part of the patella. This condition leads to supraphysiological loadings on the patellofemoral joint. Sagittal patellar tilt should be considered in the evaluation and management of patellar cartilage defects. Taking sagittal plane malalignment into consideration in patellofemoral joint evaluation will enable us to design new physical and surgical modalities.
Level of evidence
KeywordsPatellofemoral Chondromalacia patella Sagittal tilt Finite element analysis
- 1.Aksahin E, Kocadal O, Aktekin CN, Kaya D, Pepe M, Yılmaz S, Yuksel HY, Bicimoglu A (2016) The effects of the sagittal plane malpositioning of the patella and concomitant quadriceps hypotrophy on the patellofemoral joint: a finite element analysis. Knee Surg Sports Traumatol Arthrosc 24:903–908CrossRefPubMedGoogle Scholar
- 4.Belvedere C, Ensini A, Leardini A, Dedda V, Feliciangeli A, Cenni F, Timoncini A, Barbadoro P, Giannini S (2014) Tibio-femoral and patello-femoral joint kinematics during navigated total knee arthroplasty with patellar resurfacing. Knee Surg Sports Traumatol Arthrosc 22:1719–1727CrossRefPubMedGoogle Scholar
- 8.Caton J, Deschamps G, Chambat P, Lerat J, Dejour H (1981) Patella infera. Apropos of 128 cases. Rev Chir Orthop Reparatrice Appar Mot 68:317–325Google Scholar
- 19.Huang C-H, Hsu L-I, Chang T-K, Chuang T-Y, Shih S-L, Lu Y-C, Chen C-S, Huang C-H (2014) Stress distribution of the patellofemoral joint in the anatomic V-shape and curved dome-shape femoral component: a comparison of resurfaced and unresurfaced patellae. Knee Surg Sports Traumatol Arthrosc. doi:10.1007/s00167-014-3485-4 Google Scholar
- 24.Luyckx T, Didden K, Vandenneucker H, Labey L, Innocenti B, Bellemans J (2009) Is there a biomechanical explanation for anterior knee pain in patients with patella alta? Influence of patellar height on patellofemoral contact force, contact area and contact pressure. J Bone Joint Surg Br 91:344–350CrossRefPubMedGoogle Scholar
- 34.Tanamas SK, Teichtahl AJ, Wluka AE, Wang Y, Davies-Tuck M, Urquhart DM, Jones G, Cicuttini FM (2010) The associations between indices of patellofemoral geometry and knee pain and patella cartilage volume: a cross-sectional study. BMC Musculoskelet Disord 11:87CrossRefPubMedPubMedCentralGoogle Scholar