Changes in femoral trochlear morphology following surgical correction of recurrent patellar dislocation associated with trochlear dysplasia in children

2018 ◽  
Vol 100-B (6) ◽  
pp. 811-821 ◽  
Author(s):  
K. Fu ◽  
G. Duan ◽  
C. Liu ◽  
J. Niu ◽  
F. Wang
Keyword(s):  
Patellar Dislocation ◽  
Trochlear Dysplasia ◽  
Morphological Characteristics ◽  
Groove Depth ◽  
Surgical Correction ◽  
Trochlear Groove ◽  
Recurrent Patellar Dislocation ◽  
Sulcus Angle ◽  
The Mean

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.

Changes in Patellar Morphology Following Soft Tissue Surgical Correction of Recurrent Patellar Dislocation in Children With Low-grade Trochlear Dysplasia

2021 ◽  
Author(s):  
Conglei Dong ◽  
Yanyang Wang ◽  
Chao Zhao ◽  
Jinghui Niu ◽  
Wei lin ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Patellar Dislocation ◽  
Trochlear Dysplasia ◽  
Morphological Characteristics ◽  
Surgical Correction ◽  
Low Grade ◽  
Recurrent Patellar Dislocation ◽  
The Mean ◽  
Patellar Morphology

Abstract Purpose: Studies indicated that patellofemoral joint dysplasia could be caused by patellar dislocation. The purpose of the study was to investigate the changes in patellar morphology following soft tissue surgical correction of recurrent patellar dislocation in children with low-grade trochlear dysplasia.Methods: The prospective study was performed between November 2007 and December 2012. Finally, 25 cases, with the mean age of 8.4 years (range from 7 to 10 years), were admitted to our study. All patients were diagnosed as bilateral recurrent patellar dislocation associated with femoral trochlear dysplasia. The knee that had suffered an injury or dislocated most frequently was treated with medial patellar retinacular plasty (Group S). The contralateral knee, which served as a control was treated conservatively (Group C). Axial CT scans were undertaken in all patients to assess the patellar morphological characteristics on a particular axial image which was established at the point with the greatest patellar width based on measurements preoperatively and at the final follow-up.Results: Preoperatively, there were no statistically significant differences between the patellar morphology in the two groups (P>0.05). Many radiological parameters of patellar morphology were significantly different between the two groups at the final follow-up, including well-known parameters, such as the mean patellar width (Group S, 40.58 mm (SD 1.26); Group C, 36.41 mm (SD 1.17); p < 0.001), the mean patellar thickness (Group S, 11.59 mm (SD 0.74); Group C, 9.38 mm (SD 0.56); p < 0.001) and the mean wiberg index (Group S, 0.54 (SD 0.06); Group C, 0.72 (SD 0.08); p < 0.001). Little known parameters such as the ratio of length of lateral patella to medial patella (Group S, 1.26 (SD 0.17); Group C, 1.69 (SD 0.21); p < 0.001), which is a measurement of facet asymmetry. However, the wiberg angle was not significantly different between the two groups (Group S, 128.63° (SD 9.05); Group C, 125.47° (SD 13.96); p > 0.05) at the final follow-up.Conclusions: The patellar morphology can be significantly improved by early (before epiphyseal closure) soft tissue surgical correction in children with patellar instability associated with low-grade femoral trochlear dysplasia (Dejour A and B).

Surgical Treatment With Closing-Wedge Distal Femoral Osteotomy for Recurrent Patellar Dislocation With Genu Valgum

2018 ◽  
Vol 46 (7) ◽  
pp. 1632-1640 ◽  
Author(s):  
Kyung Wook Nha ◽  
Yoonwon Ha ◽  
Seungmin Oh ◽  
Vivek P. Nikumbha ◽  
Sae Kwang Kwon ◽  
...  
Keyword(s):  
Surgical Treatment ◽  
Patellar Dislocation ◽  
Femoral Osteotomy ◽  
Genu Valgum ◽  
Lateral Release ◽  
Trochlear Groove ◽  
Recurrent Patellar Dislocation ◽  
Distal Femoral Osteotomy ◽  
The Mean

Background: Closing-wedge distal femoral osteotomy (CWDFO)—combined with medial reefing and lateral release, if necessary— has been used to treat recurrent patellar dislocation (RPD) with genu valgum. Purpose: To evaluate the clinical and radiologic outcomes of surgical treatment with CWDFO for treatment of RPD with genu valgum. Study Design: Case series; Level of evidence, 4. Methods: Fourteen consecutive patients (23 knees) with RPD and genu valgum were treated with CWDFO. Patients with a minimum 2-year follow-up period were eligible for this study. Patients with prior failed surgery were also eligible. Radiographic evaluation was performed with mechanical femorotibial and lateral distal femoral angle. The radiographic parameters presenting patellar positions and pathologic abnormalities associated with RPD were evaluated. Chondral lesion changes in second-look arthroscopic examination were examined, and clinical outcomes (eg, occurrence of redislocation, range of motion, and clinical scores) were assessed pre- and postoperatively at a minimum of 2 years. Results: At a mean follow-up of 30.7 months (range, 25-62 months), the mean mechanical femorotibial and mechanical lateral distal femoral angles changed significantly from valgus 5° (range, 2°-11°) to varus 3° (2°-11°; P < .001) and from 83° (range, 78°-86°) to 89° (84°-92°; P < .001), respectively. The mean patellar congruence angle improved from 40° lateral (range, 20°-53° lateral) to 4° medial (23° medial to 21° lateral; P < .001), as did the lateral patellofemoral angle from 26° (range, 8°-62°) to 9° (0°-15°; P < .001). Computed tomography scans showed that the mean distance of patellar lateral shift decreased from 13.5 mm (range, 4-22 mm) to 2.0 mm (–4 to 5 mm; P < .001). The mean tibial tubercle to trochlear groove distance significantly decreased from 20.4 to 13.5 mm ( P < .001), while the Caton-Deschamps ratio did not change significantly after surgery ( P = .984). Chondral lesions of the patella and trochlear groove significantly improved or were maintained. None of the patients experienced subluxation or redislocation after surgery. Patellar instability symptoms also improved, as validated by radiographic and other clinical outcomes. Conclusion: CWDFO combined with medial reefing and lateral release successfully treated RPD with genu valgum for a minimum follow-up of 2 years, with improved patellar alignment and stability.

scholarly journals Changes in patellar morphology following surgical correction of recurrent patellar dislocation in children

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Weifeng Li ◽  
Qian Wang ◽  
Hui Li ◽  
Shunyi Wang
Keyword(s):  
Patellar Dislocation ◽  
Morphological Characteristics ◽  
Surgical Correction ◽  
Ct Scans ◽  
Control Group ◽  
Recurrent Patellar Dislocation ◽  
Radiological Parameters ◽  
Significant Difference ◽  
Patellar Morphology

Abstract Background The aim of this study was to evaluate patellar morphological changes following surgical correction of recurrent patellar dislocation in children. Methods A total of 35 immature children aged 5 to 10 years who suffered from bilateral recurrent patellar dislocation associated with abnormal patella morphology were enrolled in this study. The knees with the most frequent dislocations (treated with medial patellar retinacular plasty) were selected as the study group (SG), and those undergoing conservative treatment for the contralateral knee were selected as the control group (CG). Computed tomography (CT) scans were performed on all children preoperatively and at the last follow-up to evaluate morphological characteristics of the patella. Results All the radiological parameters of the patella showed no significant difference between the two groups preoperatively. At the last follow-up for CT scans, no significant differences were found for the relative patellar width (SG, 54.61%; CG, 52.87%; P = 0.086) and the relative patellar thickness (SG, 26.07%; CG, 25.02%; P = 0.243). The radiological parameters including Wiberg angle (SG, 136.25°; CG, 122.65°; P < 0.001), modified Wiberg index (SG, 1.23; CG, 2.65; P < 0.001), and lateral patellar facet angle (SG, 23.35°; CG, 15.26°; P < 0.001) showed statistical differences between the two groups. Conclusions The patellar morphology can be improved by early surgical correction in children with recurrent patellar dislocation. Therefore, early intervention is of great importance for children diagnosed with recurrent patellar dislocation.

scholarly journals Changes in Patellar Morphology Following Surgical Correction of Recurrent Patellar Dislocation in Children

2021 ◽  
Author(s):  
Weifeng Li ◽  
Qian Wang ◽  
Hui Li ◽  
shunyi wang
Keyword(s):  
Patellar Dislocation ◽  
Morphological Changes ◽  
Morphological Characteristics ◽  
Surgical Correction ◽  
Ct Scans ◽  
Control Group ◽  
Recurrent Patellar Dislocation ◽  
Radiological Parameters ◽  
Significant Difference

Abstract Background: The aim of this study was to evaluate the morphological changes of patella following surgical correction of recurrent patellar dislocation in children. Methods: 35 immature children aged 5 to 10 years who suffered from bilateral recurrent patellar dislocation associated with abnormal patella morphology. The knee had most frequently patellar dislocation, which was underwent medial patellar retinacular plasty, and defined as in the study group(SG). The contralateral knee was treated conservatively and defined as in the control group (CG). Computed tomography (CT) scans were performed on all children preoperatively and at the last follow-up to evaluate the patellar morphological characteristics. Results: All the radiological parameters of the patella, showed no significant difference between the two groups, Preoperatively. At the last follow-up for CT scans, no signifcant diferences were evaluable for the relative patellar width (SG, 54.61%; CG, 52.87%; p=0.086) and the relative patellar thickness (SG, 26.07% ; CG, 25.02%; p = 0.243). The radiological parameters including Wiberg-angle (SG, 136.25°; CG, 122.65°; p < 0.001), modified Wiberg-index (SG, 1.23; CG, 2.65 ; p < 0.001), and lateral patellar facet angle (SG, 23.35° ; CG, 15.26°; p < 0.001) showed statistical differences between the two groups. Conclusions: The morphology of the patella can be improved by early surgical correction in children with recurrent patellar dislocation. Early intervention for children with recurrent patellar dislocation is important.

Bisect offset ratio and cartilaginous sulcus angle are good combined predictors of recurrent patellar dislocation in children and adolescents

2021 ◽  
pp. jisakos-2020-000461
Author(s):  
Sheanna Maine ◽  
Christina Ngo-Nguyen ◽  
Martina Barzan ◽  
Chris Stockton ◽  
Luca Modenese ◽  
...  
Keyword(s):  
Patellar Dislocation ◽  
Trochlear Dysplasia ◽  
Pediatric Population ◽  
Tibial Tubercle ◽  
Trochlear Groove ◽  
Recurrent Patellar Dislocation ◽  
Patellar Tilt ◽  
Level Of Evidence ◽  
Femoral Torsion ◽  
Sulcus Angle

ObjectivesRecurrent patellar dislocation (RPD) is found most commonly in the juvenile population. While risk factors have been well-established in adults, there remains a paucity in radiographical data to define normal and pathoanatomical juvenile cohorts. The objectives of this paper were to elucidate the differences in the patellofemoral joint between RPD and typically developed (TD) juvenile populations, using MRI measurements, and determine the best independent and combined predictors of RPD.MethodsA prospective, cross-sectional study was conducted with 25 RPD and 24 TD participants aged between 8 and 19 years. MR images were obtained to assess common measures of lower limb alignment, patellofemoral alignment, and trochlear dysplasia.ResultsSignificant differences were evident for acetabular inclination, tibial-femoral torsion, tibial tubercle-to-trochlear groove (TT-TG) distance, lateral patellar tilt (LPT), cartilaginous sulcus angle (CSA) and bisect offset ratio (BOR). CSA and BOR were included in the final predictive model, which correctly classified 89.4% of RPD cases.ConclusionRadiographical parameters that stratify risk of RPD in adults are also able to predict RPD in the pediatric population (TT-TG, LPT, CSA and BOR). Together, CSA and BOR accurately identified 89.4% of RPD. These measures should be included in the evaluation of pediatric patients who present with patellar dislocation.Level of evidenceLevel II.

The 3-in-1 Procedure for Recurrent Dislocation of the Patella in Skeletally Immature Children and Adolescents

2009 ◽  
Vol 37 (9) ◽  
pp. 1814-1820 ◽  
Author(s):  
Francesco Oliva ◽  
Mario Ronga ◽  
Umile Giuseppe Longo ◽  
Vittorino Testa ◽  
Giovanni Capasso ◽  
...  
Keyword(s):  
Children And Adolescents ◽  
Patellar Dislocation ◽  
Case Series ◽  
Skeletal Maturation ◽  
Isokinetic Strength ◽  
Skeletally Immature ◽  
Recurrent Patellar Dislocation ◽  
Level Of Evidence ◽  
The Mean

Background Recurrent patellar dislocations are common injuries in children and adolescents. The subjective and functional results of soft tissue surgical management in a population that was skeletally immature at the time of surgery have not been reported. Hypothesis The 3-in-1 procedure is an effective treatment for recurrent patellar dislocation in skeletally immature patients. Study Design Case series; Level of evidence, 4. Methods Twenty-five skeletally immature patients (age at operation, 13.5 ± 3.8 years) who were practicing sports and suffering from recurrent unilateral patellar dislocation were included in the study and followed until skeletal maturation. Clinical evaluation included the modified Cincinnati rating system and the Kujala score, anthropometry, plain radiography, and isokinetic dynamometry. Results The average follow-up was 3.8 years (range, 2.5-6 years). The mean modified Cincinnati score increased from 51.7 ± 12.6 preoperatively to 94.3 ± 10.8 (P < .02), while the mean Kujala scores increased from 52.4 ± 12.7 preoperatively to 93.8 ± 14.2 (P < .02). The Insall-Salvati index remained essentially unchanged, being 1.04 ± 0.2 preoperatively and 1.02 ± 0.3 at latest follow-up. Significant differences were found between the operated and the contralateral limb in the various isokinetic strength variables at all angular velocities measured at the latest follow-up (.05 < P < .0042). Conclusion The 3-in-1 procedure is a safe, reliable management option for recurrent patellar dislocation in skeletally immature patients. Side-to-side differences in isokinetic strength and in anthropometric indices persist despite subjective success of the procedure.

scholarly journals Increased tibial tubercle-trochlear groove and patellar height indicate a higher risk of recurrent patellar dislocation following medial reefing

2021 ◽  
Author(s):  
Marc-Daniel Ahrend ◽  
Tobias Eisenmann ◽  
Moritz Herbst ◽  
Boyko Gueorguiev ◽  
Gabriel Keller ◽  
...  
Keyword(s):  
Patellar Dislocation ◽  
Recurrent Dislocation ◽  
Patellar Height ◽  
Tibial Tubercle ◽  
Trochlear Groove ◽  
Recurrent Patellar Dislocation ◽  
Patellar Tilt ◽  
Level Of Evidence ◽  
Sulcus Angle ◽  
Patellar Shift

Abstract Purpose Identifying anatomical risk factors on recurrent dislocation after medial reefing is important for deciding surgical treatment. The present study aimed to retrospectively analyze the preoperative magnetic resonance imaging (MRI)-based parameters of patients treated with medial reefing and whether these parameters lead to a higher risk of recurrent dislocation. Methods Fifty-five patients (18.6 ± 6.6 years) who underwent medial reefing after primary traumatic patellar dislocation (84% with medial patellofemoral ligament [MPFL] rupture) were included. Patients were followed up for at least 24 months postoperatively (3.8 ± 1.2 years) to assess the incidence of recurrent patellar dislocation. In patients without recurrent dislocation, the Kujala and subjective IKDC scores were assessed. Moreover, the tibial tubercle-trochlear groove (TT-TG), sulcus angle, patellar tilt, patellar shift, and lateral trochlea index (LTI) were measured. The patellar height was measured using the Caton-Dechamps (CDI), Blackburne-Peel (BPI), and Insall-Salvati index (ISI). The cohort was subclassified into two groups with and without recurrent dislocation. Differences between groups were analyzed with respect to the MRI parameters. Results Forty percent had a pathological sulcus angle of > 145°, 7.2% had an LTI of < 11°, 47.3% had a patellar tilt of > 20°, and 36.4% had a TT-TG of ≥ 16 mm. Increased patellar height was observed in 34.5, 65.5, and 34.5% of the patients as per CDI, BPI, and ISI, respectively. Nineteen (34.5%) patients suffered from recurrent dislocation. Compared with patients without recurrent dislocation, those with recurrent dislocation had a significantly lower LTI (p = 0.0467). All other parameters were not significantly different between the groups. Risk factor analysis showed higher odds ratios (OR > 2), although not statistically significant, for MPFL rupture (OR 2.05 [95% confidence interval 0.38–11.03], LTI (6.6 [0.6–68.1]), TT-TG (2.9 [0.9–9.2]), and patellar height according to ISI (2.3 [0.7–7.5]) and CDI (2.3 [0.7–7.5])). Patients without recurrent dislocation had a Kujala score of 93.7 ± 12.1 (42–100) points and an IKDC score of 90.6 ± 11.7 (55.2–100) points. Conclusion Anatomical, MRI-based parameters should be considered before indicating medial reefing. A ruptured MPFL, an LTI < 11°, a TT-TG ≥ 16 mm, a patellar tilt > 20 mm, and an increased patellar height according to ISI and CDI were found to be associated, although not significantly, with a higher risk (OR > 2) of recurrent patellar dislocation after medial reefing. Thorough preoperative analysis is crucial to reduce the risk of recurrent dislocation in young patient cohorts. Level of evidence Level IV

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
Keyword(s):  
Knee Flexion ◽  
Patellar Instability ◽  
Trochlear Dysplasia ◽  
Breech Presentation ◽  
Trochlear Groove ◽  
Mechanical Theory ◽  
Predisposing Factor ◽  
Sulcus Angle ◽  
Pathologic Findings ◽  
The Mean

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.

scholarly journals Evaluation of risk correlation between recurrence of patellar dislocation and damage to the medial patellofemoral ligament in different sites caused by primary patellar dislocation by MRI: a meta-analysis

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Boyong Jiang ◽  
Chenggang Qiao ◽  
Yuting Shi ◽  
Yizhong Ren ◽  
Changxu Han ◽  
...  
Keyword(s):  
Surgical Treatment ◽  
Patellar Dislocation ◽  
Medial Patellofemoral Ligament ◽  
Meta Analysis ◽  
Recurrent Dislocation ◽  
Cochrane Library ◽  
Trochlear Groove ◽  
Recurrent Patellar Dislocation ◽  
Sulcus Angle ◽  
Dislocation Group

Abstract Purpose Non-surgical treatment of primary patellar dislocation has a high risk of recurrent dislocation; thus, we tried to identify injuries in which sites of the medial patellofemoral ligament (MPFL) were most associated with recurrent dislocation by analyzing relevant original literature in order to provide improved suggestions on early surgical treatment. Methods According to the preset retrieval strategy, the original studies were retrieved until January 2020 using MEDLINE, Embase and Cochrane Library. Review Manager 5.3 software was used to summarize and compare the differences of recurrent dislocation of MPFL injuries at different attachments. Results Although the incidence of recurrent patellar dislocation at the femoral attachment of MPFL was higher overall (femoral only vs. patellar only vs. combined: 37.6% vs. 32.3% vs. 35.8%), no statistical difference was found among the three groups (femoral only vs. patellar only, RR = 1.32 [95% CI 0.89–1.95]; P = 0.17) (femoral only vs. combined, RR = 1.15 [95% CI 0.59–2.22]; P = 0.68) (patellar only vs. combined, RR = 0.94 [95% CI 0.69–1.29]; P = 0.72). In addition, the sulcus angle of recurrent dislocation group is significantly greater than that in the non-recurrent dislocation group (MD = 3.06 [95% CI 0.42–5.70]; P = 0.02). Conclusions Based on the pooled data collected from the original studies available, the risk of recurrent patellar dislocation due to damage to the MPFL at different sites did not differ. Additionally, the sulcus angle in the group with recurrent dislocation was considerably higher when comparing with the group without recurrent dislocation, that is, the shallower and flatter of the trochlear groove, the higher the risk of recurrent patellar dislocation.

scholarly journals Preoperative Complete Patellofemoral Dislocation in Extension Predicts an Inferior Clinical Outcome After Medial Patellofemoral Ligament Reconstruction in Patients With Recurrent Patellar Dislocation

2020 ◽  
Vol 8 (7) ◽  
pp. 232596712093898
Author(s):  
ZhiJun Zhang ◽  
GuanYang Song ◽  
QianKun Ni ◽  
Tong Zheng ◽  
Yanwei Cao ◽  
...  
Keyword(s):  
Patellar Dislocation ◽  
Trochlear Dysplasia ◽  
Tibial Tubercle ◽  
Control Group ◽  
3 Dimensional ◽  
Patellar Maltracking ◽  
Patient Reported ◽  
The Mean ◽  
Redislocation Rate

Background: Habitual patellar dislocation in extension (HPD-E) is a distinctive subtype of recurrent patellar dislocation (RPD); HPD-E represents the most severe type of patellar maltracking in RPD. It has been reported that the presence of preoperative patellar maltracking is associated with a worse clinical outcome after medial patellofemoral ligament (MPFL) reconstruction (MPFL-R). Purpose: To describe the radiological characteristics of HPD-E and to compare clinical outcomes after MPFL-R among patients with and without preoperative HPD-E. Study Design: Cohort study; Level of evidence, 3. Methods: From January 2012 to December 2015, a total of 230 consecutive patients (246 knees) with RPD were treated with MPFL-R alone or combined with tibial tubercle osteotomy. Among them, 28 patients diagnosed with HPD-E by preoperative 3-dimensional computed tomography (CT; HPD-E group) were matched in a 1:1 fashion to 28 control participants who did not show HPD-E (control group). Routine radiography and CT were performed to evaluate patellar height, trochlear dysplasia, tibial tubercle–trochlear groove distance, and torsional deformities. The mean patellar laxity index and lateral patellar translation assessed with stress radiography were measured preoperatively and postoperatively to quantify MPFL laxity. At minimum 2-year follow-up, patient-reported outcomes (Kujala, Lysholm, and Tegner scores), patellar maltracking, and redislocation rates were compared between the HPD-E and control groups. Results: The radiological characteristics of the HPD-E group were as follows: 89% (25/28) of patients had severe trochlear dysplasia (Dejour type B or D), and the mean femoral anteversion angle was 35.5° ± 4.7°. At the final follow-up, the HPD-E group had a significantly lower Kujala score (76.2 vs 84.5, respectively; P = .001), Lysholm score (75.4 vs 86.6, respectively; P < .001), and Tegner score (4.1 vs 5.8, respectively; P = .021) compared with the control group. The postoperative patellar laxity index (43% vs 19%, respectively; P < .001) and redislocation rate (25% vs 0%, respectively; P = .01) were significantly higher in the HPD-E group than in the control group. Conclusion: Preoperative 3-dimensional CT is a reliable method of identfying patients with HPD-E. Treatment of HPD-E by MPFL-R alone or combined with tibial tubercle osteotomy resulted in a higher redislocation rate, more severe MPFL residual laxity, and lower patient-reported outcome scores compared with patients without HPD-E who underwent MPFL-R.

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