High-grade Trochlear Dysplasia Research Articles

Good 5-year results and a low redislocation rate using an á la carte treatment algorithm for patellofemoral instability in patients with severe trochlea dysplasia.

Trochlear dysplasia is a major risk factor for recurrent patellar instability, reduced quality of lifeand osteoarthritis of the patellofemoral joint. Patellar instability in patients with trochlear dysplasia can be treated by trochleoplasty, usually in combination with medial patellofemoral ligament reconstruction (MPFL-R). An á la carte treatment algorithm, which also addresses patella alta, lateralisation of the tibial tuberosityand valgus or torsional malalignment when present has been standard in one clinic for treatment of patellar instability patients since 2009, based on the hypothesis that it results in optimal subjective and clinical outcome, normalisation of the lateral trochlea inclination (LTI) angle and a low rate of patellar redislocation. This prospective study reports the 5-year results for consecutive patients with high-grade trochlea dysplasia operated according to the algorithm 2010-2017, evaluated preoperatively and 1, 2and 5 years postoperatively. Clinical information on previous surgery and postoperative patellar stability, range-of-motion (ROM)and subsequent surgery were registered. Subjective outcome was evaluated by four patient-reported outcome measures (PROMs): Kujala, Lysholm, International Knee Documentation Committee and Knee injury and Osteoarthritis Outcome Score. The LTI angle was measured pre- and postoperatively on magnetic resonance imaging scans. There were 131 patients (87 females) with a median age of 22 years (range: 14-38). All had a trochleoplasty and an MPFL-R. Additional procedures (tibial tuberosity medialisation/distalisation and/or femoral/tibial osteotomy) were performed in 52%. All PROM scores improved from preoperatively to 1-year follow-up with further improvement at 2 and 5 years after surgery (p < 0.05). Three patients (2%) had a traumatic patellar dislocation 9, 12and 24 months postoperativelyand 38% underwent subsequent surgery (hardware removal, arthroscopically assisted brisement force, knee arthroscopy). A normalisation of the LTI angle (≥11°) was achieved in 76%. Treatment according to the à la carte algorithm for patients with patellar instability and high-grade trochlear dysplasia resulted in significant clinical and subjective improvement in all PROM scores and a very low redislocation rate (2%) 5years after surgery. Level II.

Medial orientation of the trochlear groove is a strong indicator of high-grade trochlear dysplasia.

The objective is to evaluate the orientation of the trochlear groove in patients with objective patellar instability (OPI) compared to a control group. The hypothesis is that the trochlear groove angle (TGA) is correlated with the severity of the trochlear dysplasia. From 2019 to 2023, magnetic resonance imaging of 82 knees with OPI were compared with 82 control knees. TGA quantified the angle between the femoral anatomical axis and the trochlear groove. The intraclass correlation coefficient for TGA was evaluated. Central spur in the sagittal plane (CSSP) and cranial trochlear orientation (CTO) angle were also measured. TGA, CSSP and CTO were compared between the two groups. A TGA subgroup analysis separating the OPI group into low-grade (CSSP < 5 mm or negative CTO) and high-grade dysplasia (CSSP ≥ 5 mm or positive CTO) was also performed. A significant difference (p < 0.001) was found between the TGA of the OPI group (mean [SD], 11.3 [3.7]°) and the control group (4.2 [2.5]°). TGA for patients with high-grade dysplasia (11.9 [3.8]°) was significantly higher than patients with low-grade dysplasia (9.6 [3.9]°). Patients with OPI have a TGA of 11°, compared to the control group, which exhibits a TGA of 4°. The femoral mechanical axis can be considered an appropriate threshold for separating these two groups. Furthermore, TGA is correlated with the severity of dysplasia. Case-control study. Level III.

The role of the most cranial trochlear orientation in patellar maltracking to better characterise trochlear morphology.

The purpose of our study is to describe a magnetic resonance imaging quantitativeparameter to assess the morphology of the trochlea that could be measurable from normal to high-grade trochlear dysplasia while evaluating the most proximal slice with trochlear cartilage. Two groups of patients have been compared: patients with no patellofemoral pain, no previous trauma and undergoing surgery for a suspected isolated meniscal tears (group A) and patients with objective patellar instability (group B). The cranial trochlear orientation (CTO) angle is defined as the angle between the posterior bicondylar line and the most lateral and most medial points on the subchondral bone covered by cartilage digitised on the first and most cranial image with the trochlear cartilage clearly visible. The final cohort included 253 patients (109 in group A and 144 in group B). CTO was significantly higher in group B (-2.5 ± 8.4 vs. -10.8 ± 5,1; p < .001). Moreover, 75% of knees in group B had a CTO > -7°, while 75% of knees in group A had a CTO < -7°. CTO was measurable in all 253 knees, whereas the lateral trochlear inclination and the sulcus angle were measurable in only 202 knees. The entire cohort was also divided into knees with CTO ≤ 0° and CTO > 0°. All knees with a CTO > 0 were in group B, and 49% of knees with CTO < 0 were in group B. CTO was positively correlated with lateral patellar tilt. CTO is the only parameter that can be measured on the most cranial slice, in every patient, even in high-grade trochlear dysplasia. According to this new system, the axial trochlear shape may be divided into two types: a positive CTO and a negative CTO, with the trochlea serving, respectively, as a medial and lateral barrier. Level III.

Clinical outcomes of derotational femoral osteotomy combined with medial patellofemoral ligament reconstruction in patients with patellar dislocation and increased femoral anteversion unaffected by the pattern of distribution of femoral torsion.

The aim of this study was to evaluate the clinical effect of derotational femoral osteotomy combined with medial patellofemoral ligament reconstruction for patellar dislocation and the effect of the distribution of femoral torsion at different segments on postoperative function. Forty-two patients with patellar dislocation who underwent derotational femoral osteotomy from 2017 to 2021 were retrospectively analysed. All patients received computed tomography scans from the hip to the knee to evaluate correction of the femoral anteversion (FA) angle, patellar tilt angle (PTA) and congruence angle (CA) after derotational femoral osteotomy. Subjective scores, such as the Kujala, Lysholm, International Knee Documentation Committee (IKDC), Tegner and visual analog scale (VAS) scores, were used to evaluate knee function before and after the operation. Patients with supracondylar torsion > distal torsion were categorized into the supracondylar torsion group and patients with distal torsion > supracondylar torsion were categorized into the distal torsion group. Subgroup analyses were performed. No presentation of redislocation occurred in these patients at the minimum 2-year follow-up visit. The mean preoperative FA angle in the supracondylar torsion group was 30.2° ± 4.2°, and the mean postoperative FA angle was 14.5° ± 2.5° (p < 0.001). The mean preoperative FA angle was 26.7° ± 1.4° and the mean postoperative FA angle was 14.1° ± 1.4° in the distal torsion group. In addition, postoperative PTA and CA were significantly corrected in both groups (p < 0.001). The postoperative Kujala, Lysholm, IKDC, Tegner and VAS scores were significantly improved in both groups (p < 0.001). Subgroup analyses showed a higher preoperative FA in the supracondylar torsion group and a higher occurrence of high-grade trochlear dysplasia in the distal torsion group. However, there was no significant difference in their postoperative clinical outcomes. Through a minimum of 2-year follow-up visits of patients with patellar dislocation and increased FA, it was found that derotational femoral osteotomy could significantly reduce FA and improve subjective knee function. The pattern of torsion distribution did not significantly affect the clinical outcomes of derotational femoral osteotomy. These findings readvised orthopaedic surgeons that derotational femoral osteotomy remains the preferred procedure for correcting rotational malalignment, but that they should be more cautious about its indications. Level IV.

Sulcus-Deepening Trochleoplasty for High-Grade Trochlear Dysplasia: Demystifying the Procedure-a Review of the Current Literature.

The most common and biomechanically influential pathoanatomic risk factor for recurrent patellofemoral instability is trochlear dysplasia. Sulcus-deepening trochleoplasty is a procedure developed to address high-grade trochlear dysplasia in the setting of patellofemoral instability. The purpose of this paper is to outline the current classification and surgical management of trochlear dysplasia as well as to review the current literature on the clinical outcomes and complications of sulcus-deepening trochleoplasty. This review outlines the most recent literature reporting evidence behind the decision-making to perform a trochleoplasty in the setting of patellofemoral instability and high-grade trochlear dysplasia. Critical parameters include grade of trochlear dysplasia, severity of symptoms, pertinent physical examination findings, surgical techniques, modifications for skeletally immature patients, and considerations for the revision setting. Historic studies have elicited concerns regarding high reported complication rates for trochleoplasty; however, recent studies consistently report good clinical outcomes and acceptable complication rates, similar to those of other patellar stabilizing procedures. The addition of a trochleoplasty in patients with high-grade dysplasia results in a lower re-dislocation rate, significant improvements in patient-reported outcome measures (PROMs) as well as high levels of patient satisfaction and return to sport. The use of sulcus-deepening trochleoplasty for the treatment of high-grade dysplasia and recurrent patellofemoral instability is a well-established technique with good outcomes and an acceptable complication profile. In patients with high-grade dysplasia, trochleoplasty results in lower re-dislocation rates, high patient satisfaction scores, and good clinical and functional outcomes. An understanding of trochleoplasty and its indications should be in the armamentarium of surgeons treating patellofemoral instability.

Derotational distal femur osteotomy combined with medial patellofemoral ligament reconstruction yields satisfactory results in recurrent patellar dislocation with excessive femoral anteversion angle and trochlear dysplasia.

The purpose of this study was to evaluate the clinical outcomes of medial patellofemoral ligament (MPFL) reconstruction combined with derotational distal femur osteotomy in patients with recurrent patellar dislocation who had excessive femoral anteversion angle and trochlear dysplasia. Between 2015 and 2020, 64 patients (64 knees) with recurrent patellar dislocation, who had excessive femoral anteversion angle (≥ 25°) and trochlear dysplasia and were surgically treated using derotational distal femur osteotomy and MPFL reconstruction, were eligible for this retrospective study. These patients were assigned to two groups according to the grade of trochlear dysplasia. Group A (type A trochlear dysplasia, n = 33) and Group B (type B, C, D trochlear dysplasia, n = 31). Preoperative and postoperative patellar tilt angle (PTA), Caton-Deschamps index (CD-I), tibial tubercle-trochlear groove (TT-TG) distance and femoral anteversion angle were evaluated. Patient outcomes were assessed using the preoperative and postoperative International Knee Documentation Committee (IKDC) score, Kujala score, Lysholm score, Tegner score, and visual analog scale (VAS) score. A total of 64 patients (64 knees) were evaluated in this study, with a mean follow-up period of 28.4 ± 3.6months. There were no cases of wound infection, osteotomy site fractures, deep venous thrombosis of the lower extremities, or re-dislocation in the two groups during the postoperative follow-up period. All patients returned to full extension and flexion. The postoperative Tegner score, Lysholm score, Kujala score, IKDC score, VAS score, PTA, CD-I, TT-TG distance, and femoral anteversion angle were significantly improved compared with the preoperative status (P < 0.05). There was no significant difference between the two groups (n.s.). MPFL reconstruction combined with derotational distal femur osteotomy showed satisfactory clinical outcomes during follow-up in patients with recurrent patellar dislocation who had excessive femoral anteversion angle and trochlear dysplasia. Even patients with high-grade trochlear dysplasia showed satisfactory results. For those patients, additional surgery is not necessary. Level III.

Effect of Lower Extremity Torsion on Clinical Outcomes After Medial Patellofemoral Ligament Reconstruction and Tibial Tubercle Transfer for Recurrent Patellofemoral Instability

Background: Increased femoral torsion (FT) or tibial torsion (TT) has been suggested to be a potential risk factor for recurrent patellofemoral instability. However, the influence of increased FT or TT on the postoperative clinical outcomes of recurrent patellofemoral instability has rarely been investigated. Purpose: To assess the effect of increased FT or TT on postoperative results in patients with recurrent patellofemoral instability after combined medial patellofemoral ligament reconstruction (MPFLR) and tibial tubercle transfer, along with the influence of other risk factors. Study Design: Cohort study; Level of evidence, 3. Methods: Out of 91 patients, the study’s analyses included 86 patients with recurrent patellofemoral instability who were treated with MPFLR and tibial tubercle transfer and enrolled between April 2020 and January 2021. FT and TT were assessed using preoperative computed tomography images. According to the torsion value of FT or TT, patients were categorized into 3 groups for each of FT and TT: group A (<20°), group B (20°-30°), and group C (>30°). Patellar height, femoral trochlear dysplasia, and the tibial tuberosity–trochlear groove (TT-TG) distance were also assessed. Patient-reported outcome scores (Tegner, Kujala, International Knee Documentation Committee [IKDC], Lysholm, and Knee injury and Osteoarthritis Outcome Score [KOOS]) were evaluated pre- and postoperatively. Clinical failure of MPFLR was recorded. Subgroup analysis was conducted to evaluate the effect of increased FT or TT on the postoperative outcomes. Results: A total of 86 patients were enrolled with a median follow-up time of 25 months. At the final follow-up, all functional scores improved significantly. Patella alta, high-grade trochlear dysplasia, and increased TT-TG distance did not have any significant effect on the postoperative functional scores. Regarding FT, subgroup analysis indicated that all functional scores of group C were lower than those of groups A and B except the KOOS knee-related Quality of Life score. For TT, group C had lower scores than group A for all functional outcomes except Tegner and KOOS Quality of Life and lower scores than group B for Kujala, IKDC, KOOS (Symptoms and Sport and Recreation subscales), Tegner, and Lysholm scores. The comparison between group A and group B, whether for FT or TT, revealed no significant differences. Conclusion: For patients with recurrent patellofemoral instability, increased lower extremity torsion (FT or TT >30°) was associated with inferior postoperative clinical outcomes after combined MPFLR and tibial tubercle transfer.

Clinical and Second-look Arthroscopic Results for Derotational Distal Femoral Osteotomy With Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Dislocation With Increased Femoral Anteversion: A Series of 102 Cases With a Minimum Clinical Follow-up of 2 Years

Background: Derotational distal femoral osteotomy (DDFO) has been used to treat patients with recurrent patellar dislocation (RPD) with increased femoral anteversion. However, no study has reported second-look arthroscopic findings in the patellofemoral joint after DDFO. Purpose: To report clinical and second-look arthroscopic outcomes for DDFO with combined medial patellofemoral ligament reconstruction (MPFL-R) in treating RPD with increased femoral anteversion. Study Design: Case series; Level of evidence, 4. Methods: From 2015 to 2019, 131 consecutive patients (144 knees) with RPD were treated with combined MPFL-R and DDFO. Patients with a femoral anteversion angle >30° and a minimum 2-year clinical follow-up period were included in the study. Three-dimensional computed tomography was performed to evaluate rotational deformities of the lower leg. Radiographic parameters presenting bony abnormalities associated with RPD were measured. Second-look arthroscopic evaluations were available for 86 knees to assess patellar tracking and chondral lesion changes. Moreover, clinical and radiologic outcomes were assessed pre- and postoperatively at a minimum 2 years. Results: A total of 102 knees in 92 patients were included in the present study with a mean clinical follow-up of 4.1 years (range, 2.0-5.6 years). Mean ± SD femoral anteversion changed significantly from 34.7°± 7.5° preoperatively to 11.3°± 0.2° postoperatively (P < .001), and mean tibial tubercle–trochlear groove distance decreased significantly from 19.6 ± 3.5 mm preoperatively to 17.4 ± 3.2 mm postoperatively (P < .001). In the majority of knees, at the time of second-look arthroscopic assessment, chondral lesion status remained unchanged at the lateral patellar facet (96%) and trochlear groove (95%); in contrast, chondral damage at the medial patellar facet was aggravated in 9 cases (10%). All functional scores (Tegner, Lysholm, visual analog scale, and Kujala scores) improved significantly at final follow-up. None of the patients experienced redislocation or subluxation after surgery. Conclusion: Chondral lesions in the patellofemoral joint remained unchanged in the majority of cases in second-look arthroscopy after combined MPFL-R and DDFO. Moreover, high-grade trochlear dysplasia and arthroscopic residual patellar maltracking might be associated with cartilaginous deterioration at the medial patellar facet after surgery.

Failure of isolated medial patellofemoral ligament reconstruction in children: Risk factors and management.

Patellofemoral instability is a frequent cause of referral in pediatric sports medicine. Isolated medial patellofemoral ligament reconstruction is widely used and provides satisfactory outcomes with a low failure rate. Given the success of this surgical technique, the literature on medial patellofemoral ligament reconstruction failures in the pediatric population is limited. Moreover, given the multifactorial nature of patellofemoral instability, the heterogeneity of the current literature, and the paucity of pediatric studies, medial patellofemoral ligament reconstruction failures are often difficult to analyze. The purpose of this study was to retrospectively review the associated risk factors, surgical management, and the clinical outcomes at 2-year follow-up of skeletally immature patients that presented to our clinic with a failed medial patellofemoral ligament reconstruction. Of the 181 cases in 155 patients included in this study, treatment failed in 12 (7%). All 12 patients presented with at least one risk factor for patellofemoral instability, the most common being trochlear dysplasia and a high-grade J sign. We conclude that isolated medial patellofemoral ligament reconstruction for patellofemoral instability in children has a low failure rate. Clinicians must assess pre-operative risk factors before surgical treatment is considered. A high-grade J sign and high-grade trochlear dysplasia were associated with medial patellofemoral ligament reconstruction failure in this cohort. Tailoring treatment to patients' associated risk factors selection may improve outcomes.

Poster 235: Surgical Management of Patellar Instability in Adolescents with High Grade Trochlear Dysplasia

Objectives:High-grade trochlear dysplasia (HGTD) has previously been identified as a risk factor for failure of surgical management of patellofemoral instability (PFI). However, limited data exists on the influence of the type of surgical procedure performed on postoperative outcomes in these patients. The purpose of this study was to identify the rates of failure of primary PFI surgery in patients with HGTD compared to those without HGTD and to assess the effect of the type of surgery on recurrent instability and return to OR.Methods:We retrospectively reviewed patients aged ≤19 years who underwent primary surgery for PFI at our institution between 2008 and 2017. Patients underwent procedures including medial retinacular plication (MRP), medial patellofemoral ligament reconstruction (MPFLR), tibial tubercle osteotomy (TTO), or combined procedures. We excluded patients with incomplete imaging data, BMI >30kg/m2, those that underwent surgery for fixation of a chondral fracture >1cm, and patients with a diagnosis of syndromic disorder. Trochlear dysplasia was evaluated based on pre-operative MRI. Patients were divided between those that had HGTD and those without HGTD. Comparisons were made between the two groups and logistic regression analysis was utilized to determine if surgery category was associated with rate of recurrence in the HGTD patients.Results:Three-hundred three patients, average age 15.1 years, underwent primary surgical stabilization for PFI with median follow up time of 3.0 years. Forty-nine percent (149/303) of the cohort had HGTD. Demographics were comparable between HGTD groups (Table 1). When compared to the patients without HGTD, patients with HGTD showed similar rates of recurrent instability, return to the OR for instability, and return to the OR for other reasons. Looking at patients with just HGTD, there was a significant association between surgery type and outcomes (Table 2). HGTD patients who underwent MPFLR had a 63% decrease in the odds of experiencing recurrent instability compared to those undergoing MRP (OR=0.37; p=0.03). Similarly, the TTO surgery group had an 80% decrease in the odds of experiencing recurrent instability compared to patients undergoing MRP (OR=0.20; p=0.002).Conclusions:While adolescents with PFI and HGTD overall have similar results after surgical stabilization, there is a significant effect of the type of surgery performed. Patients with HGTD that underwent MRP had significantly more instability and return to the OR for instability surgeries than patients that underwent other procedures. Based on this data, adolescents with PFI and HGTD should be considered for more powerful surgeries to limit the risk of recurrence or return to the OR.Table 1.Patient Demographics and Outcomes Compared Between Trochlear Dysplasia Groups (n=303)Table 2.Outcomes of Patients with HGTD Compared by Type of Surgery (N=149).

Surgical Management of Patellofemoral Instability in Adolescents with High Grade Trochlear Dysplasia

Background:High-grade trochlear dysplasia (HGTD) has previously been identified as a risk factor for failure of surgical management of patellofemoral instability (PFI). However, limited data exists on the influence of the type of surgical procedure performed on postoperative outcomes in these patients.Hypothesis/Purpose:The purpose of this study was to identify the rates of failure of primary PFI surgery in patients with HGTD compared to those without HGTD and to assess the effect of the type of surgery on recurrent instability and return to OR.Methods:A retrospective review was performed on patients aged ≤19 years who underwent primary surgery for PFI at a single tertiary care center between 2008 and 2017. Patients underwent procedures including medial retinacular plication/reefing/advancement (MRP), graft-based medial patellofemoral ligament reconstruction (MPFLR), tibial tubercle osteotomy with or without MRP (TTO), or combined MPFLR + TTO. Exclusion criteria were BMI >30kg/m2, surgery for fixation of chondral fractures >1cm, and diagnosis of a syndromic disorder. Trochlear dysplasia was evaluated based on pre-operative MRI according to the Dejour classification system. Those with Dejour grade B or higher were designated as having HGTD. Comparisons were made between HGTD patients and non-HGTD patients, with logistic regression utilized to determine if surgery type was associated with recurrent PFI and revision PFI surgery.Results:303 patients (mean age 15.1 years, 71% female) underwent primary surgical stabilization for PFI with median follow up time of 3.0 years. Approximately half (149/303, 49%) of the cohort had HGTD. Demographics were comparable between HGTD and non-HGTD patients (Table 1). HGTD and non-HGTD cohorts showed similar rates of post-operative instability, revision PFI surgery, and non-PFI secondary surgery. HGTD patients (Table 2) who underwent MPFLR had a 63% decrease in the odds of post-operative PFI compared to those who underwent MRP (OR=0.37; p=0.03). HGTD patients who underwent TTO had an 80% decrease in the odds of post-operative PFI compared to patients undergoing MRP (OR=0.20; p=0.002).Conclusion:Adolescents with PFI and HGTD have similar results after surgical stabilization to those patients without HGTD. Within the HGTD cohort, however, the type of surgery performed significantly influenced outcome. Patients with HGTD that underwent MRP had significantly more recurrent PFI and revision PFI surgery than patients that underwent other procedures, suggesting a limited role for this procedure in this sub-population of PFI patients.Table 1.Patient Demographics and Outcomes Compared Between Trochlear Dysplasia Groups (n=303).Table 2.Outcomes of Patients with HGTD Compared by Type of Surgery (N=149).

Rotational alignment of the femoral trochlea in Asians: Implication on implant choice and position for managing isolated patellofemoral osteoarthritis

Introduction Maltracking of the patella is a key contributor to early failure of patellofemoral arthroplasty (PFA). Native femoral trochlear morphology dictates implant rotation and patella tracking of in-lay PFA implants. This is the first study amongst Asians designed to assess the normal rotational alignment of the trochlear groove and evaluate its implication on PFA implant choice and position. Methods Trochlear inclination angle (TIA) was measured from 211 magnetic resonance images of Asian knees retrieved from a single centre in Hong Kong. TIA assesses rotation of the femoral trochlear groove relative to the axis perpendicular to Whiteside’s line (anteroposterior axis of the femur). Results The mean trochlear inclination in normal Asian knees was 11.5° ± 2.5° (mean ± standard deviation) internal rotation. High-grade dysplastic knees, according to Dejour classification, were significantly more internally rotated with a mean of 12.8° ± 3.6° (p = 0.025). Conclusion Trochlear inclination in Asians is comparable to Caucasians. In-lay PFA implants do not alter native pathological bony trochlear anatomy, and may result in patella maltracking in patients with high grade trochlear dysplasia or excessive trochlear inclination. These patients may benefit from on-lay implants, which allows restoration of normal trochlear inclination, as well as lateralisation and deepening of the trochlear groove. Patella tracking is however, dynamic and multi-factorial. Further clinical studies are therefore warranted to reconcile our anatomical findings with clinical outcomes.

Isolated MPFL reconstruction for recurrent lateral patellar instability in patients with TT-TG distance &lt;25 mm: A calculated safe risk!

Objectives: The objectives of the study were to describe the surgical technique of our modification of isolated medial patellofemoral ligament (MPFL) reconstruction, in patients with patellar instability. As per literature, isolated MPFL reconstruction is advocated if tibial tubercle-trochlear groove (TTTG) &lt;20 mm. Our study proposes isolated MPFL reconstruction in patients with TT-TG &lt;25 mm and aims to determine any predisposing anatomic variants to aid in the treatment algorithm. Materials and Methods: A retrospective analysis of 52 patients with patellar instability (TT-TG &lt;25 mm), who underwent isolated MPFL reconstruction was undertaken. The study population was divided into two groups; TT-TG &lt;20 mm and TT-TG = 20–24 mm. Both groups were assessed radiologically and on the basis of clinical and functional outcome (KUJALA score), over 5-year follow-up period. Results: The mean age of the study population was 21.98 years, with a female (63.5%) majority. Among the 52 patients included in the study, 39 patients (75%) had TT-TG &lt;20 mm and 13 patients (25%) had TT-TG = 20–24 mm. We noticed statistically significant improvement in both groups with respect to clinical and functional outcome, with no reported complications. None of the patients had patella alta or high grades of trochlear dysplasia. Conclusion: MPFL reconstruction without concomitant bony procedures can be safely performed in patients with a TT-TG &lt;25 mm, in the absence of patella alta or high-grade trochlear dysplasia. Our modification of isolated MPFL reconstruction has shown excellent long-term results. In addition, our technique uses only a single interference screw, thereby reducing cost of surgery and implant hardware.

Prevalence of Trochlear Dysplasia and Associations with Patellofemoral Pathology (166)

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.

Prevalence of Trochlear Dysplasia and Associations with Patellofemoral Pain and Instability in a Skeletally Mature Population.

Patellar instability among adolescents has an incidence of 29 to 43 per 100,000 per year. Trochlear dysplasia has been found in up to 85% of those with recurrent patellar instability. The prevalence of trochlear dysplasia in the general population has not yet been defined. The purpose of the present study was to determine the prevalence of trochlear dysplasia as defined by ultrasound in a skeletally mature population and to characterize associations of trochlear dysplasia with a history of patellofemoral instability or pain. Skeletally mature adolescents and parents of patients (≤50 years of age) who had presented to orthopaedic clinics were prospectively enrolled from 2019 to 2020. Those presenting with knee pain, open physes, prior intra-articular fracture, total knee arthroplasty, and syndromic ligamentous laxity or neuromuscular disease were excluded. Information regarding a history of anterior knee pain, patellar instability, and/or surgery was obtained, and an abbreviated Anterior Knee Pain Scale (AKPS) was collected. An AKPS score of ≥4 was considered positive. Bilateral ultrasound of the knee was performed, and the osseous sulcus angle of the trochlea and the trochlear depth were measured. Basic descriptive statistics are reported. One hundred and two patients (203 knees) were studied. The mean sulcus angle was 144.1° ± 6.8°, and the mean trochlear depth was 5.5 ± 1.4 mm. High-grade trochlear dysplasia was defined as the 95th percentile and above, which was shown to be a sulcus angle of ≥154° or a trochlear depth of ≤3 mm for female patients and ≤4 mm for male patients. The prevalence of high-grade trochlear dysplasia was 5.4% based on the sulcus angle and 9.9% based on trochlear depth. Knees with high-grade trochlear dysplasia based on the sulcus angle were 11 times more likely to have had previous patellar instability (p = 0.013). The prevalence of high-grade trochlear dysplasia in the general population is approximately 10%, and there may be an association with patellar instability. The use of ultrasound to diagnose trochlear dysplasia may prove to be a rapid and useful tool for guiding patient education and treatment decisions. Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Interobserver reliability is higher for assessments with 3D software-generated models than with conventional MRI images in the classification of trochlear dysplasia

PurposeTrochlear dysplasia is a significant risk factor for patellofemoral instability. The severity of trochlear dysplasia is commonly evaluated based on the Dejour classification in axial MRI slices. However, this often leads to heterogeneous assessments. A software to generate MRI-based 3D models of the knee was developed to ensure more standardized visualization of knee structures. The purpose of this study was to assess the intra- and interobserver agreements of 2D axial MRI slices and an MRI-based 3D software generated model in classification of trochlear dysplasia as described by Dejour.MethodsFour investigators independently assessed 38 axial MRI scans for trochlear dysplasia. Analysis was made according to Dejour’s 4 grade classification as well as differentiating between 2 grades: low-grade (types A + B) and high-grade trochlear dysplasia (types C + D). Assessments were repeated following a one-week interval. The inter- and intraobserver agreement was determined using Cohen’s kappa (κ) and Fleiss kappa statistic (κ). In addition, the proportion of observed agreement (po) was calculated for assessment of intraobserver agreement.ResultsThe assessment of the intraobserver reliability with regard to the Dejour-classification showed moderate agreement values both in the 2D (κ = 0.59 ± 0.08 SD) and in the 3D analysis (κ = 0.57 ± 0.08 SD). Considering the 2-grade classification, the 2D (κ = 0.62 ± 0.12 SD) and 3D analysis (κ = 0.61 ± 0.19 SD) each showed good intraobserver matches. The analysis of the interobserver reliability also showed moderate agreement values with differences in the subgroups (2D vs. 3D). The 2D evaluation showed correspondences of κ = 0.48 (Dejour) and κ = 0.46 (high / low). In the assessment based on the 3D models, correspondence values of κ = 0.53 (Dejour) and κ = 0.59 (high / low) were documented.ConclusionOverall, moderate-to-good agreement values were found in all groups. The analysis of the intraobserver reliability showed no relevant differences between 2 and 3D representation, but better agreement values were found in the 2-degree classification. In the analysis of interobserver reliability, better agreement values were found in the 3D compared to the 2D representation. The clinical relevance of this study lies in the superiority of the 3D representation in the assessment of trochlear dysplasia, which is relevant for future analytical procedures as well as surgical planning.Level of evidenceLevel II.

Assessment of patellar dislocations in childhood and adolescence : Accident-related or predisposition-related?

Numerous predisposing factors are known for patellar dislocations but the extent to which these or the trauma cause the dislocation is often unclear. This study investigated whether the analysis of the accident mechanism and anatomical predisposition in juvenile patellar dislocations enables a conclusion as to the causality. Retrospective cohort study, evidence levelIII. In-house employers' liability insurance association (BG) cases with the diagnosis of patella dislocation in patients under 18years were descriptively evaluated with respect to demographic and predisposing aspects as well as regarding accident information. The accident mechanisms were sorted into subgroups: direct impact, trivial trauma, fall, torsional trauma. A total of 54 patellar dislocations were identified with apatient age of 14 years (range 9-18 years). Amild valgus configuration was found in 39% of the cases, on average normal torsion, a tibial tuberosity-trochlea groove (TTTG) distance of 17 mm (range 8-24mm), with 41% ahigh proportion of patella alta and atrochlear deformity in 57%. Only 20% of the children had no relevant predispositions. The trivial traumas showed the highest proportion of recurrent dislocations with 50% and in the other accident categories the proportion of first dislocations was >75%. In the fall cohort the rate of children without relevant predisposition was highest. The predisposition rate in infantile patellar dislocations is high; however, falls are always significant accident events as well as medial direct impact. Torsional trauma is also a significant causative factor, unless high-grade trochlear dysplasia is present, whereas trivial traumas are not.

Radiographic clues to the unstable knee: are findings of trochlear dysplasia on lateral knee radiographs reliable and predictive of patellar dislocation?

Trochlear dysplasia (TD) is a key predisposing risk factor for patellar instability (PI) and lateral patellar dislocation (LPD) injuries. It is useful to understand the reliability of radiographic findings of TD and the accuracy of knee radiographs in diagnosing patients with recent LPD. The purposes of our study are to evaluate the inter-rater reliability of specific radiographic signs of PI and staging of TD between radiologists and orthopedic surgeons, and to identify which findings are associated with recent LPD. This retrospective study comprised 336 patients aged 8 to 18 who obtained knee radiographs over a 3-year period. Two radiologists and two orthopedic surgeons, blinded to patient history, examined radiographs for indicators of PI. Using data from 19 confirmed LPD cases and 317 controls, inter-observer agreement (kappa, Pearson's correlation coefficient) was assessed, as was the odds ratio for likelihood of LPD. There was nearly perfect agreement between radiologists for patella-tendon ratios (Pearson's correlation coefficient 0.8377, P < 0.0001) and discrimination between normal knees and high-grade TD (kappa 0.9213, P < 0.0001). There is fair agreement between radiologists and surgeons distinguishing between normal knees and high-grade TD (kappa 0.5843, P < 0.0001). Lateral knee radiographs interpreted as high-grade TD were highly predictive of LPD (odds ratio 7.58-54.8) among all readers. There is high agreement between radiologists when evaluating lateral knee radiographs for signs of TD, validating the results of prior literature. Radiographic findings TD, patella alta, and effusion are variable predictors of recent LPD, greatest among patients with TD.

Outcomes of MPFL reconstruction with tibial tubercle transfer for recurrent patellar instability with high grade trochlear dysplasia in Indian population

BackgroundPatellar instability is a painful condition which affects the quality of life and mobility of young individuals. The aim of this study is to observe the results of medial patello-femoral ligament reconstruction with hamstring autograft along with a modified Fulkerson osteotomy, for recurrent instability of patella with high-grade trochlear dysplasia in Indian population. Materials & methodsWe conducted a prospective observational study of 26 knees (21 patients) who attended our outpatient department from June 2014 to February 2019, with recurrent instability of the patella and high-grade trochlear dysplasia. All knees were treated with MPFL reconstruction with hamstring autograft and modified Fulkerson osteotomy. ResultsThe mean follow-up period was 30 months (range: 24–50). The mean Lysholm scores improved from 49.9 (range: 30–63) preoperatively to 82.5 (range: 51–100) (p < 0.05), Kujala scores from 55.5 (36–67) to 85.9 (55–100) and International Knee Documentation Committee (IKDC) scores from 50.2 (31.6–62.3) to 82.9 (54.7–98.3) (p < 0.05) at 2 years follow-up. TT-TG distance decreased from 21.2 mm (18–25) to 11.6 mm (10–13) (p < 0.05) and patellar tilt angle decreased from 24.2° (18°-35°) to 7.2° (5°-10°) (p < 0.05). One knee had superficial skin infection in immediate post-operative period. Three knees had postoperative stiffness, which improved on manipulation under anesthesia. Six knees had implant irritation from the osteotomy screws which were removed after bony union was achieved. Functional scores were low in two knees due to patello-femoral pain, but they did not have recurrent instability. ConclusionMPFL reconstruction with tibial tubercle transfer gives good functional outcomes in 92.3% patients with recurrent patellar instability, associated with high-grade trochlear dysplasia in Indian population.

Why compromise the patella? Five-year follow-up results of medial patellofemoral ligament reconstruction with soft tissue patellar fixation

PurposeThis study investigates the redislocation rate and functional outcome at a minimum follow-up of five years after medial patellofemoral ligament (MPFL) reconstruction with soft tissue patellar fixation for patella instability.MethodsPatients were retrospectively identified and knees were evaluated for trochlea dysplasia according to Dejour, for presence of patella alta and for presence of cartilage lesion at surgery. At a minimum follow-up of five years, information about an incident of redislocation was obtained. Kujala, Lysholm, and Tegner questionnaires as well as range of motion were used to measure functional outcome.ResultsEighty-nine knees were included. Follow-up rate for redislocation was 79.8% and for functional outcome 58.4%. After a mean follow-up of 5.8 years, the redislocation rate was 5.6%. There was significant improvement of the Kujala score (68.8 to 88.2, p = 0.000) and of the Lysholm score (71.3 to 88.4, p = 0.000). Range of motion at follow-up was 149.0° (115–165). 77.5% of the knees had patella alta and 52.9% trochlear dysplasia types B, C, or D. Patellar cartilage legions were present in 54.2%. Redislocations occurred in knees with trochlear dysplasia type C in combination with patella alta.ConclusionMPFL reconstruction with soft tissue patellar fixation leads to significant improvement of knee function and low midterm redislocation rate. Patients with high-grade trochlear dysplasia should be considered for additional osseous correction.