Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

The Radiological Work Up of Patients With Patellofemoral Pathology: ISAKOS 2015

2,263 views

Published on

Introduction: The radiological work-up of patients with patellofemoral disorders continues to be debated. The interchangeability of the tibial tubercle-trochlear groove (TT-TG) distance between computed tomography (CT) and magnetic resonance imaging (MRI) has recently been questioned. In addition, a new measurement-the tibial tubercle-posterior cruciate ligament (TT-PCL) distance-has shown that not all patients with a pathological TT-TG distance (>20 mm) have lateralization of the tibial tubercle. Another factor to consider when looking at the position of the tibial tubercle is the knee joint rotation, defined as the angle between the femoral dorsal condylar line and the tibial dorsal condylar line.

Aim: To determine, with a larger population, if the TT-TG measurements can be used interchangeably between CT and MRI and to confirm the correlation between the TT-PCL and TT-TG distances in determining tibial tubercle lateralization.

Study Design: Cohort study (diagnosis); Level of evidence, 2.
Patients with patellofemoral disorders and MRI and CT scans of the same knee (n = 141) were identified. The TT-PCL, the knee joint rotation, and TT-TG were measured independently by 2 fellowship-trained orthopaedic surgeons. Thirty measurements were repeated on a separate occasion to allow for an assessment of the intrarater reliability. The intraclass correlation coefficient (ICC) was used to assess reliability of the measurements.

Results: The mean TT-TG was 4.16 mm less on MRI (P < .05), with the mean TT-TG ± SD being 17.72 ± 5.15 mm on CT (range, 6.97-31.33 mm) and 13.56 ± 6.07 mm on MRI (range, 2-30.04 mm). The ICC for each rater comparing the 2 imaging modalities was only fair (0.54 and 0.48). The mean TT-PCL measurement was 20.32 ± 3.45 mm (range, 10.11-32.01 mm) with excellent interobserver and intraobserver reliability (>0.75). Based on the TT-TG and TT-PCL measurements, 4 groups of patients can be established. When knee joint rotation is compared among groups, an increased TT-TG may result from true lateralization of the tibial tubercle, an increased knee joint rotation, or both.

Conclusions: Based on a statistically significant mean difference (4.11 mm) and only a fair ICC (0.54 and 0.48) for raters comparing the 2 modalities, the measurements for the TT-TG cannot be used interchangeably between CT and MRI. Therefore, currently accepted values for TT-TG based on CT scans should not be applied to an MRI scan. The TT-PCL measurement is a measure of true lateralization of the tibial tubercle, while the TT-TG is an amalgamated measure of true lateralization and knee joint rotation.

Published in: Health & Medicine
  • Be the first to comment

The Radiological Work Up of Patients With Patellofemoral Pathology: ISAKOS 2015

  1. 1. The Radiological Work Up Of Patients With Patellar Femoral Pathology: Should The TT-TG Distance Be Measured On MRI And What Is Its Relationship To The TT-PCL Distance? C Anley1, G Morris1, A Saithna1, S James2, M Snow1 1 Arthroscopy Division, The Royal Orthopaedic Hospital, Birmingham, UK 2 Radiology Department, The Royal Orthopaedic Hospital, Birmingham, UK
  2. 2. Disclosures The authors have no financial conflicts related to this poster to disclose
  3. 3. TT-TG Measurement Tibial tubercle-Trochlear groove (TT-TG) traditionally radiographic measure to determine lateralisation of TT TT-TG > 20mm on CT surgical intervention Varies with knee flexion and difficult in trochlea dysplasia Dejour H, Walch G, Nove-Josserand L, Guier C. Factors of patellar instability: an anatomic radiographic study. Knee Surg Sports Traumatol Arthrosc. 1994;2(1):19-26
  4. 4. TT-PCL Measurement TT-PCL is the mediolateral distance between the midpoint of the insertion of the patellar tendon and the medial border of the posterior cruciate ligament Measured parallel to the dorsal tibia condylar line Normal: 24 mm dTCL: Dorsal tibia condylar line PCL: Posterior cruciate ligament; TT-PCL: Tibial tubercle-Posterior Cruciate Ligament distance Seitlinger G, Scheurecker G, Hogler R, Labey L, Innocenti B, Hofmann S. Tibial tubercle-posterior cruciate ligament distance: a new measurement to define the position of the tibial tubercle in patients with patella dislocation. Am J Sports Med. 2012;40(5):1119-1125 TT-PCL
  5. 5. Objective Radiographic study to: 1. Review whether TT-TG on CT and MRI are interchangeable 2. Establish if there is a correlation between TT lateralisation as indicated by TT-TG and TT-PCL
  6. 6. Methods 141 scans (108F 33M) with patellar pathology and both MRI and CT scan, were identified on the hospital PACS system. Ave age: 28.5 yrs (10-59, SD ±11.13 yrs) TT-TG, TT-PCL and Knee Joint Rotation were measured independently by two fellowship trained orthopaedic surgeons according to the methods used by Seitlinger et al and Shoettle Thirty measurements where repeated on a separate occasion to allow for an assessment of the intrarater reliability
  7. 7. Results: TT-PCL Mean TT-PCL: 20.32mm (10.11-32.01, SD: ± 3.45mm) Excellent (> 0.75) inter- and intraobserver agreement 14% (20/141) TT-PCL > 24 mm of which 55% (11/20) had TT-TG >20mm on CT 31% (44/141) TT-TG > 20mm on CT of which 25% (11/44) had TT-PCL >24mm
  8. 8. Results: TT-TG CT vs MRI Interobserver and intraobserver agreement was considered excellent (> 0.75) for both MRI and CT (0.98 and 0.97) ICC for each rater comparing the two imaging modalities was only fair (0.54 and 0.48) Measurements are not interchangeable between the two modalities CT MRI Mean 17.72mm 13.56mm Mean difference: 4.16mm Range 6.97-31.33mm 2-30.04mm SD ±5.15 ±6.07 P value p<0.001
  9. 9. Results Based on the TT-TG and TT-PCL measurements, 4 groups of patients can be established. When comparing knee joint rotation (KJR) between groups, we noted that an increased TT- TG may result from either true lateralisation of the TT, an increased knee joint rotation or a combination of both.
  10. 10. Results: TG and PCL TG <20mm PCL<24mm TG<20mm PCL>24mm TG>20mm PCL<24mm TG>20mm PCL>24mm Number (%) 88 (62.4%) 9 (6.4%) 33 (23.4%) 11 (7.8%) Mean TG Mean PCL 15.04 18.92 15.06 25.92 23.22 20.82 25.42 25.88 SD TG SD PCL ±3.12 ±2.66 ±3.55 ±2.42 ±2.77 ±2.27 ±3.99 ±1.75 CT KJA 6.8 6.7 12.5 10.3 P < 0.05
  11. 11. Conclusion Commonly accepted values for the TT-TG distance cannot be used interchangeably between CT and MRI and a TT-TG >20mm measured on MRI should not be used as an indication for surgery
  12. 12. Conclusion The TT-PCL measurement is a measure of true lateralisation of the tibial tubercle while the TT- TG is an amalgamated measure of true lateralisation and KJR. The clinical relevance of these different groups requires further investigation and may explain the poor results in some patients following tibial tubercle transfers.
  13. 13. References Dejour H, Walch G, Nove-Josserand L, Guier C. Factors of patellar instability: an anatomic radiographic study. Knee Surg Sports Traumatol Arthrosc. 1994;2(1):19-26 Seitlinger G, Scheurecker G, Hogler R, Labey L, Innocenti B, Hofmann S. Tibial tubercle-posterior cruciate ligament distance: a new measurement to define the position of the tibial tubercle in patients with patella dislocation. Am J Sports Med. 2012;40(5):1119-1125 Schoettle PB, Zanetti M, Seifert B, Pfirrmann CW, Fucentese SF, Romero J. The tibial tuberosity–trochlear groove distance: a comparative study between CT and MRI scanning. Knee. 2006;13:26-31.

×