scholarly journals Trochlear dysplasia - congenital anomaly or biomechanical development

2018 ◽  
Vol 71 (3-4) ◽  
pp. 96-99
Author(s):  
Zlatko Temelkovski ◽  
Zoran Bozinovski ◽  
Alan Andonovski ◽  
Biljana Andonovska

Introduction. The aim of this study was to investigate the appearance of the trochlear groove in infants and to present the possible causes for the development of trochlear dysplasia as one of the most severe pathologic findings in patients with patellar instability. Material and Methods. Knee ultrasonography was performed in 200 infants, 3 to 6 months of age. The measurements were made at 30 and 60 degrees of knee flexion, in order to measure the trochlear bone and cartilaginous sulcus angle on the patellar surface of the femur and to determine the degree of trochlear dysplasia. A 7-megahertz probe was used for measurements, which was tangentially placed with the reference to the posterior femoral joint. Results. A completely flat trochlear bony sulcus angle was registered in all infants aged 3 to 6 months. The mean cartilaginous sulcus angle was between 149 ? 5.4? and 19 infants had a sulcus angle over 159?. Eleven infants with trochlear dysplasia were in breech presentation at birth. Conclusion. Our study showed that the cartilaginous part of the trochlear groove was already well developed at birth. Breech presentation of the fetus could be a predisposing factor for dysplasia of the cartilaginous part of the trochlear groove. The bony part of the trochlear groove is dysplastic in infants and it gradually gets deeper, later getting a shape of the overlying articular cartilage. The influence of the Delpech law, with lower pressure in the trochlear groove, could be the possible mechanical theory explaining the development of the trochlear dysplasia in the later stage of the childhood.

2020 ◽  
Vol 8 (6) ◽  
pp. 232596712092548
Author(s):  
Matthew Colatruglio ◽  
David C. Flanigan ◽  
Sarah Harangody ◽  
Robert A. Duerr ◽  
Christopher C. Kaeding ◽  
...  

Background: Recurrent patellar instability is frequently treated surgically with reconstruction of the medial patellofemoral ligament (MPFL). Patients with significant patella alta, trochlear dysplasia, and/or an elevated tibial tubercle–trochlear groove (TT-TG) distance may benefit from a concurrent bony procedure such as tibial tubercle osteotomy or trochleoplasty. The indications to perform such procedures are traditionally based on imaging criteria but remain controversial. Patellar apprehension is common in patients with patellar instability but typically resolves in higher degrees of knee flexion. Hypothesis: The persistence of patellar apprehension at greater than 60° of knee flexion is associated with patella alta, an increased TT-TG distance, and trochlear dysplasia. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 76 patients with recurrent patellar instability were prospectively identified in a sports medicine clinic. Patellar apprehension was evaluated in each patient. Apprehension was defined as the patient reporting that the patella felt unstable to lateral patellar translation. Apprehension was first assessed at full knee extension and repeatedly assessed as the knee was flexed in 10° intervals, as measured using a goniometer. The degree of flexion at which patellar apprehension disappeared was recorded. Plain radiographs and magnetic resonance imaging (MRI) scans were obtained for all patients. Patellar height was assessed with the Caton-Deschamps (CD) index, and trochlear morphology was assessed through measurements of the sulcus angle and depth on MRI and classified using the Dejour classification system. Imaging measurements of patients in whom apprehension resolved by 60° of knee flexion were compared with measurements for those with apprehension that persisted deeper into flexion. Results: Apprehension resolved by 60° of flexion in 56 patients and persisted into deeper flexion in 20 patients. The patients with a delayed resolution of apprehension demonstrated a higher CD index; elevated TT-TG distance; increased sulcus angle; decreased sulcus depth; and higher incidence of Dejour type B, C, or D dysplasia (all P < .05). Of the 20 patients with a delayed resolution of apprehension, 18 had either Dejour type B, C, or D dysplasia or a CD index of at least 1.30. A delayed resolution of apprehension was present in 11 of the 16 patients with Dejour type B, C, or D dysplasia. Conclusion: Overall, 90% of patients with significant patella alta and the majority of patients with high-grade trochlear dysplasia demonstrated patellar apprehension that persisted beyond 60° of knee flexion. Additionally, 90% of patients with persistent apprehension had significant patella alta and/or trochlear dysplasia. Further work is needed to evaluate the utility of these findings to inform surgical decision-making in this population.


2020 ◽  
Vol 8 (7_suppl6) ◽  
pp. 2325967120S0034
Author(s):  
Matthew Colatruglio ◽  
David Flanigan ◽  
Sarah Harangody Robert Magnussen

Objectives: Recurrent patellar instability is frequently treated surgically with reconstruction of the medial patellofemoral ligament (MPFL). Patients with significant patella alta, trochlear dysplasia, and/or an elevated tibial tubercle-trochlear groove (TT-TG) distance may benefit from a concurrent bony procedure such as a tibial tubercle osteotomy or trochleoplasty. The indications to include such procedures are traditionally based on imaging criteria, but remain controversial. Patellar apprehension is common in patients with patellar instability but typically resolves in higher degrees of knee flexion. We hypothesis that the persistence of patellar apprehension at greater than 60 degrees of knee flexion is associated with patella alta, increased TT-TG distance, and trochlear dysplasia. Methods: Seventy-six patients with recurrent patellar instability were prospectively identified in a sports medicine clinic. Patellar apprehension was evaluated in each patient. Apprehension was defined as the patient reporting that the patella felt unstable to lateral patellar translation. Apprehension was first assessed at full knee extension and repeated assessed as the knee was flexed in 10 degrees intervals as measured with a goniometer. The degree of flexion at which patellar apprehension disappeared was recorded. Plain films and MRI were obtained in all patients. Patellar height was assessed with the Caton-Deschamps (CD) index and trochlear morphology was assessed through measurement of the sulcus angle and depth on MRI and classification with the Dejour classification system. Imaging measurements of patients in which apprehension resolved by 60 degrees of knee flexion were compared with measures for those with apprehension that persisted deeper into flexion. Results: Apprehension resolved by 60 degrees of flexion in 55 patients and persisted into deeper flexion in 21 patients. The patients with delayed resolution of apprehension demonstrated a higher CD Index, elevated TT-TG distance, increased higher sulcus angle, decreased trochlear depth, and a higher incidence of Dejour B, C, or D dysplasia (all p < 0.05, Table 1). Of the 21 patients with delayed resolution of apprehension, 18 had either Dejour B, C, or D dysplasia or a Caton-Deschamps Index of at least 1.3. Delayed resolution of apprehension was present in 11 of the 16 patients with Dejour B, C, or D dysplasia. Conclusion: The presence of patellar apprehension in higher degrees of knee flexion is associated with patella alta, increased TT-TG distance, and more severe trochlear dysplasia. Further work is needed to evaluate utility of this exam finding to inform surgical decision-making in this population.


2020 ◽  
Vol 8 (7_suppl6) ◽  
pp. 2325967120S0048
Author(s):  
Lilah Fones ◽  
Regina Kostyun ◽  
James Pace

Objectives: Osteochondral damage is a potential consequence of patellar instability that is associated with an increased risk of arthritis and lower patient reported outcomes. Currently, there is little evidence of risk factors associated with osteochondral damage in the setting of patellar instability. The purpose of this study was to identify the association of patient demographics, chronicity of patellar instability, and radiographic measurements with osteochondral damage in adolescent patients with patellar instability. Methods: Upon obtaining Institutional Review Board approval, a chart review was conducted to identify patients 18 years of age and younger treated for patellar instability between 2013 and 2018 at a tertiary referral center. Patients with both acute traumatic and chronic recurrent dislocations with magnetic resonance imaging (MRI) results available were included. Patients were excluded if they had a previous ipsilateral patellar instability surgical intervention. MRI exams were reviewed, and measurements were conducted for Caton-Deschamps (CD) ratio, proximal tibial tubercle to trochlear groove (pTT-TG), distal tibial tubercle to trochlear groove (dTT-TG), lateral trochlear inclination (LTI), lateral patellar inclination (LPI), and sulcus angle. Logistical regression was conducted using binary outcome of presence or absence of osteochondral damage (Statistical Analysis Software, Cary, NC). Odds ratios were calculated for parameters that were statistically significant (p<0.05). Results: A total of 129 knees and 122 patients (average age at first visit 14.4±3.0, 51% female) were identified with patellar instability, of which 53% had osteochondral damage. Approximately one third of patients (67%) were treated with surgical management. There was no association identified between osteochondral damage and sex, age, BMI, symptom duration, physeal status, or number of dislocation (acute vs chronic). Of the radiographic measurements evaluated, LTI, LPI, sulcus angle and dTT-TG all had a statistically significant association with the presence of osteochondral damage (Table 1). Every 1-unit decrease in LTI (more trochlear dysplasia) was associated with a 6% increased chance of osteochondral damage. Every 1-unit increase in LPI, sulcus angle, and dTT-TG is associated with an increased chance of osteochondral damage of 5.5%, 5.8%, and 11.3%, respectively. The CD ratio and pTT-TG had no association with osteochondral damage. Confidence intervals, p-values, and odds ratios are presented in Table 1. Conclusions: There is an association between radiographic parameters, particularly those that correlate with higher levels of trochlear dysplasia, and osteochondral damage in adolescent patients with patellar instability, but no association with being either an acute or chronic dislocator. Clinically, this may impact the management of patients presenting with patellar instability and no radiographic evidence of osteochondral damage. In these patients, clinicians may have a lower threshold for surgical interventions in those with higher levels of trochlear dysplasia as evidenced by decreased LTI and an increased LPI, sulcus angle, and dTT-TG.


2019 ◽  
Vol 47 (6) ◽  
pp. 1323-1330 ◽  
Author(s):  
Elliot Sappey-Marinier ◽  
Bertrand Sonnery-Cottet ◽  
Padhraig O’Loughlin ◽  
Herve Ouanezar ◽  
Levi Reina Fernandes ◽  
...  

Background: Reconstruction of the medial patellofemoral ligament (MPFL) is widely acknowledged as an integral part of the current therapeutic armamentarium for recurrent patellar instability. The procedure is often performed with concomitant bony procedures, such as distalization of the tibial tuberosity or trochleoplasty in the case of patella alta or high-grade trochlear dysplasia, respectively. At the present time, few studies have evaluated the clinical effectiveness of MPFL reconstruction as an isolated intervention. Purpose: To report the clinical outcomes of isolated MPFL reconstruction in cases of patellar instability and to identify predictive factors for failure. Study Design: Case series; Level of evidence, 4. Methods: A retrospective analysis of prospectively collected data was performed, including all patients who had undergone isolated MPFL reconstruction between January 2008 and January 2014. Preoperative assessment included the Kujala score, assessment of patellar tracking (“J-sign”), and radiographic features, such as trochlear dysplasia according to Dejour classification, patellar height with the Caton-Deschamps index (CDI), tibial tubercle–trochlear groove distance, and patellar tilt. The Kujala score was assessed postoperatively. Failure was defined by a postoperative patellar dislocation or surgical revision for recurrent patellar instability. Results: A total of 239 MPFL reconstructions were included; 28 patients (11.7%) were uncontactable and considered lost to follow-up. Thus, 211 reconstructions were analyzed with a mean follow-up of 5.8 years (range, 3-9.3 years). The mean age at surgery was 20.6 years (range, 12-48 years), and 55% of patients were male. Twenty-seven percent of patients had a preoperative positive J-sign, and 93% of patients had trochlear dysplasia (A, 47%; B, 25%; C, 15%; D, 6%). The mean CDI was 1.2 (range, 1.0-1.7); mean tibial tubercle–trochlear groove distance, 15 mm (range, 5-30 mm); and mean patellar tilt, 23° (range, 9°-47°). The mean Kujala score improved from 56.1 preoperatively to 88.8 ( P < .001). Ten failures were reported that required surgical revision for recurrent patellar instability (4.7%). Uni- and multivariate analyses highlighted 2 preoperative risk factors for failure: patella alta (CDI ≥1.3; odds ratio, 4.9; P = .02) and preoperative positive J-sign (odds ratio, 3.9; P = .04). Conclusion: In cases of recurrent patellar instability, isolated MPFL reconstruction would appear to be a safe and efficient surgical procedure with a low failure rate. Preoperative failure risk factors identified in this study were patella alta with a CDI ≥1.3 and a preoperative positive J-sign.


2021 ◽  
Vol 8 (1) ◽  
Author(s):  
A. Castelli ◽  
E. Jannelli ◽  
E. Ferranti Calderoni ◽  
G. Galanzino ◽  
A. Ivone ◽  
...  

Abstract Purpose This study aimed to highlight short- and medium-term outcomes of combined medial patello-femoral ligament (MPFL) reconstruction and anterior tibial tuberosity (ATT) transposition surgery in patients with recurrent patellar instability and different degrees of trochlear dysplasia. Methods Between January 2014 and May 2019, 25 patients with patellar instability underwent a surgical procedure combining the lowering/transposition of the ATT and the MPFL reconstruction. Each patient were preoperative assessed by Kujala score, International Knee Documentation Committee (IKDC), Tegner activity level scale. The assessment of instability predisposing factors was carried out with patellar height, tibial tuberosity-trochlear groove (TT-TG) distance, trochlear dysplasia, sulcus angle, patellar tilt and MPFL injuries. Functional outcomes were evaluated with Kujala, IKDC and Tegner scores at 3, 6 and 12 months after surgery. Results The average age of the patients was 20 years (range 13–43 years). Pre- operative Caton–Deschamps index was pathological in 10 (40%). Sulcus angle was elevated in 13 patients (52%) and TT-TG distance was irregular in 17 patients (68%). Trochlear dysplasia was present in 13 patients (9 type A, 3 type B, 1 type C according to Dejour’s Classification). No re-dislocation occurred during the follow-up. There was a significant increase in the Kujala, IKDC and Lysholm scores after 3, 6 and 12 months, and the results were compared for the different follow-up times and patient’s trochlear dysplasia degree. Conclusion This prospective observational longitudinal study identified good clinical outcomes in patients who underwent MPFL reconstruction and ATT transposition for patellar instability. Finally, the different risk factors for patellar instability examined, particularly the presence of trochlear dysplasia, did not significantly influence the final functional results, which range from good to excellent without re-dislocation episodes.


2019 ◽  
Vol 7 (7_suppl5) ◽  
pp. 2325967119S0030
Author(s):  
S. Evan Carstensen ◽  
Matthew Tyrrell Burrus ◽  
Scott Feeley ◽  
Jourdan M. Cancienne ◽  
David R. Diduch

Objectives: Patellar instability caused by trochlear dysplasia may be addressed by sulcus-deepening trochleoplasty. A paucity of data exists from the United States regarding this procedure and no long term follow up. The purpose of this study was to evaluate the outcome data of patients undergoing sulcus-deepening trochleoplasty for high-grade trochlear dysplasia at our institution. Methods: Sixty-four patients (71 knees) with severe trochlear dysplasia were prospectively enrolled and underwent sulcus-deepening trochleoplasty using the Dejour method from 2011-2018. Thirty-six of 71 knees (50.6%) had prior surgery and failed prior surgical management for patellar instability. Concomitant procedures during trochleoplasty were performed at varying rates. Radiographic analysis, physical examination, and clinical follow-up were obtained for all patients. At enrollment, patients completed preoperative visual analog scores (VAS), international knee documentation committee (IKDC) and Kujala scores, which were repeated at their 6 month, 1 year, 2 year, 3 year, and 4 year follow-up visits. Preoperatively, the patellotrochlear index (PTI), trochlear spur height, and trochlear depth were all measured. The patient’s sulcus angle was measured preoperatively and postoperatively on sunrise (merchant) view xray. Of the entire cohort, 43 patients (49 knees) had at least one year complete follow-up including xrays, physical exam, and patient-reported outcome measures and were included in the study. Results: The majority of patients were female (81.6%) with a mean age of 19.6 (+/- 6.8y). Follow-up ranged from 12 months to 78.4 months (mean 27.7 +/- 15.4). At the time of enrollment, mean BMI was 27.1 kg/m2 (+/-6.3) with one current smoker and one diabetic patient. Mean duration of symptoms prior to surgery was 75.2 months (+/- 72.5; r: 4-370mos). All knees were either Dejour B (81.3%) or D (18.8%) with a mean Caton-Deschamps index (CDI) of 1.20 (+/-0.2). Mean spur height preoperatively was 7.41 mm (+/1.84 mm) with a mean trochlear depth -0.18 (+/-2.71). Mean patellotrochlear index (PTI) was 0.41 (+/0.41). There were zero episodes of recurrent instability. All patients reported clinically significant improvements compared with baseline preoperative outcome scores. The mean preoperative IKDC score was 49.99, which improved to 79.86 (p&lt0.001), and the mean preoperative Kujala score was 55.88, which improved to 85.80 (p&lt0.001). Patients reported high satisfaction rates (9.5 +/-1.6 out of 10). All but 1 patient (96.9%) returned to work while 88.2% of patients were able to return to sport. Ten knees (20.4%) developed arthrofibrosis and required manipulation under anesthesia while eight of which underwent simultaneous arthroscopic lysis of adhesions. At the latest follow-up, mean knee range of motion was 132.4 +/- 13.2 degrees. Preoperative VAS was 3.31 (right) and 4.16 (left) while postoperative was 1.31 (right) and 1.76 (left) (p=0.007 R, 0.002 L). Radiographic analysis of the sulcus angle demonstrated a significant decrease from 148.86 degrees (+/-11.42) preoperatively to 135.11 degrees (+/-8.85) postoperatively (p<0.001). Conclusion: In the setting of severe trochlear dysplasia, sulcus-deepening trochleoplasty can provide a reliable and successful surgical solution to recurrent patellar instability. At a minimum of one year follow-up, the majority of patients were satisfied with their outcome corroborated by their subjective, validated outcome measures.


2021 ◽  
Vol 9 (10_suppl5) ◽  
pp. 2325967121S0028
Author(s):  
Clarabelle DeVries ◽  
James Bomar ◽  
Andrew Pennock

Objectives: Patellar instability is a common condition of adolescents with an incidence of 29 to 43 per 100,000. Trochlear dysplasia has been found in up to 85% of those with recurrent patellar instability and has been found in association with ACL rupture. However, the prevalence of trochlear dysplasia in the general population has not yet been defined. The purpose was to define the prevalence of trochlear dysplasia as defined by ultrasound in a skeletally mature population and characterize associations of trochlear dysplasia with patellofemoral pathology. Methods: Skeletally mature adolescents and parents aged 50 and under presenting to orthopedics clinics were recruited from 2019 to 2020. Those with a history of intra-articular fracture, total knee arthroplasty, and syndromic ligamentous laxity or neuromuscular disease were excluded. Surveys were collected detailing any history of knee symptoms and surgery as well as an abbreviated Anterior Knee Pain Score (AKPS) with a score of 4 or greater being considered positive. Ultrasounds were obtained of bilateral knees and the osseous sulcus angle of the trochlea as well as the trochlear depth were measured (Figure 1). Basic descriptive statistics are reported. Results: One hundred and two patients (203 knees) were studied. The mean osseous sulcus angle was 144.1±6.8° and the mean trochlear depth was 5.5±1.4mm. The distribution of outcomes of interest can be found in Table 1. High grade trochlear dysplasia was defined as two standard deviations from the mean which was shown to be a sulcus angle ≥158˚ or a trochlear depth of ≤3mm. Prevalence of high grade trochlear dysplasia based on sulcus angle was 3.0% and 5.9% based on trochlear depth. In the presence of high grade trochlear dysplasia as defined by osseous sulcus angle, there was a 32 times increased risk of previous patellar instability (p=0.007) and 10 times increased risk of a positive AKPS (p=0.016). All those with high grade trochlear dysplasia as defined by osseous sulcus angle had a history of, or current, patellofemoral pain. Conclusions: The prevalence of trochlear dysplasia in the general population is approximately 6%. There are significant associations of trochlear dysplasia not only with patellar instability but also with patellofemoral pain. Use of ultrasound to diagnose trochlear dysplasia may prove to be a rapid and useful tool in guiding patient education and treatment decisions.


2021 ◽  
Vol 0 ◽  
pp. 1-7
Author(s):  
Vijinder Arora ◽  
Abhiraj Kakkar

Objectives: In this study, we have attempted to evaluate the predisposing factors of patellar instability on magnetic resonance imaging (MRI) and to compare the significance of measurement at the level of trochlear bone versus cartilage for trochlear dysplasia. Material and Methods: Thirty patients of patellar instability were assessed on MRI for risk factors of patellar instability including trochlear dysplasia, tibial tuberosity to trochlear groove (TT-TG) distance, and patellar height ratio. Results: Twenty-one (70%) and 27 (90%) cases were positive for decreased trochlear depth when measured at the level of trochlear bone and cartilage, respectively. Eighteen (60%) and 25 (83.33%) cases were positive for trochlear facet asymmetry when measured at trochlear bone and cartilage, respectively. Twelve cases (40 %) were positive for patella alta. Ten cases (33.33%) were positive for decreased lateral trochlear inclination. Seven cases (23.3%) had increased TT to TG distance. Twenty-four cases (80%) were of age equal to or <25 years. Conclusion: According to our study, trochlear dysplasia is the most common predisposing factor of patellar instability (100%) followed by patella alta (40%) and TT-TG distance (23.3%). Trochlear depth and facet asymmetry produce better results as a predisposing factor for instability of patella when measured at the level of trochlear cartilage as compared to trochlear bone with P = 0.001.


2018 ◽  
Vol 100-B (6) ◽  
pp. 811-821 ◽  
Author(s):  
K. Fu ◽  
G. Duan ◽  
C. Liu ◽  
J. Niu ◽  
F. Wang

Aims The aim of this study was to investigate the changes in femoral trochlear morphology following surgical correction of recurrent patellar dislocation associated with trochlear dysplasia in children. Patients and Methods A total of 23 patients with a mean age of 9.6 years (7 to 11) were included All had bilateral recurrent patellar dislocation associated with femoral trochlear dysplasia. The knee with traumatic dislocation at the time of presentation or that had dislocated most frequently was treated with medial patellar retinacular plasty (Group S). The contralateral knee served as a control and was treated conservatively (Group C). All patients were treated between October 2008 and August 2013. The mean follow-up was 48.7 months (43 to 56). Axial CT scans were undertaken in all patients to assess the trochlear morphological characteristics on a particular axial image which was established at the point with the greatest epicondylar width based on measurements preoperatively and at the final follow-up. Results Preoperatively, there were no statistically significant differences between the trochlear morphology in the two groups (sulcus angle, p 0.852; trochlear groove depth, p 0.885; lateral trochlear inclination, p 0.676; lateral-to-medial facet ratio, p 0.468; lateral condylar height, p 0.899; medial condylar height, p 0.816). Many radiological parameters of trochlear morphology were significantly different between the two groups at the final follow-up, including well-known parameters, such as the mean sulcus angle (Group S, 146.27° (sd 7.18); Group C, 160.61° (sd 9.29); p < 0.001), the mean trochlear groove depth (Group S, 6.25 mm (sd 0.41); Group C, 3.48 mm (sd 0.65); p < 0.001) and the mean lateral trochlear inclination (Group S, 20.99° (sd 3.87); Group C, 12.18° (sd 1.85); p < 0.001). Lesser known parameters such as the ratio of the lateral to medial trochlear length (Group S, 1.46 (sd 0.19); Group C, 2.14 (sd 0.42); p < 0.001), which is a measurement of facet asymmetry, and the lateral and medial condylar height were also significantly different between the two groups (p < 0.001). Conclusion The femoral trochlear morphology can be improved by early (before epiphyseal closure) surgical correction in children with recurrent patellar dislocation associated with femoral trochlear dysplasia. Cite this article: Bone Joint J 2018;100-B:811–21.


2021 ◽  
pp. 036354652098781
Author(s):  
Mathias Paiva ◽  
Lars Blønd ◽  
Per Hölmich ◽  
Kristoffer Weisskirchner Barfod

Background: Tibial tubercle–trochlear groove (TT-TG) distance is often used as a measure of lateralization of the TT and is important for surgical planning. Purpose: To investigate if increased TT-TG distance measured on axial magnetic resonance images is due to lateralization of the TT or medialization of the TG. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 84 knees (28 normal [NK], 28 with trochlear dysplasia [TD], and 28 with patellar dislocation without TD [PD]) were examined. The medial border of the posterior cruciate ligament (PCL) was chosen as the central anatomic landmark. The distance from the TT to PCL (TT-PCL) was measured to examine the lateralization of the TT. The distance from the TG to the PCL (TG-PCL) was measured to examine the medialization of the TG. Between-group differences were investigated by use of 1-way analysis of variance. Results: The mean values for TT-TG distance were 8.7 ± 3.6 mm for NK, 12.1 ± 6.0 mm for PD, and 16.7 ± 4.3 mm in the TD group ( P < .01). The mean values for TT-PCL distance were 18.5 ± 3.6 mm for NK, 18.5 ± 4.5 mm for PD, and 21.2 ± 4.2 mm in the TD group ( P = .03). The mean values for TG-PCL distance were 9.6 ± 3.0 mm for NK, 7.1 ± 3.4 mm for PD, and 5.1 ± 3.3 mm in the dysplastic group ( P < .01). Conclusion: The present results indicate that increased TT-TG distance is due to medialization of the TG and not lateralization of the TT. Knees with TD had increased TT-TG distance compared with the knees of the control group and the knees with PD. The TT-PCL distance did not differ significantly between groups, whereas the TG-PCL distance declined with increased TT-TG.


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