Abstract
Introduction
Patellar instability is a common condition affecting approximately 6 individuals per 100,000, but among adolescents, this incidence is notably higher. Trochlear dysplasia has been recognized as the pathoanatomic risk factor exerting the most significant biomechanical influence. Over time, various surgical techniques have been developed to address trochlear dysplasia. The purpose of this study is to evaluate the clinical outcomes, return to sport, as well as complications and re-operation rate of sulcus deepening trochleoplasty performed in a cohort of young and active patients using the Bereiter technique.
Materials and methods
Between January 2019 and February 2022, 11 cases of recurrent patellar dislocations underwent trochleoplasty. Preoperative radiological assessment included X-rays, CT scans following the Lyons and MRI. Inclusion criteria for the study and trochleoplasty indications included patients aged 10–25 with recurrent patellar dislocations unresponsive to nonoperative treatment and minimum type B trochlear dysplasia. Clinical follow-up occurred at 1-3-6 months and annually, with control X-rays at these intervals. Patient-reported outcome scores included the Knee Society Score, Kujala score, and Karnofsky performance status scale.
Results
Between January 2019 and February 2022, 11 patients underwent trochleoplasty and were included in this study. Preoperative radiological measurements indicated mean values: sulcus angle (152.5°), trochlear depth (3.4 mm), Caton-Deschamps index (1.2), tibial tuberosity to trochlear groove (TT-TG) distance (17.5 mm), external patellar tilt angle (6.8°), femoral anteversion (11.5°), and tibial torsion (32°). All patients were followed up for at least 2 years, with an average of 43 months. Concurrent surgeries included tibial tuberosity transposition (100 %), MPFL reconstruction in 9 cases (81.8 %) and 2 patients also underwent division of the external alar ligament (18,2 %). PROMs at final follow-up showed mean values: Knee Society Score (KSS) (80.5), Kujala score (88.3), and Karnofsky performance status scale (88.8). Return to sport was reported by all active patients. Three cases required secondary surgical intervention for removal of the screws.
Conclusion
Trochleoplasty, especially with the Bereiter "thin flap" approach, improves patellofemoral congruency. Combining trochleoplasty with tibial tuberosity transposition addresses mal-tracking related to severe dysplasia and other à-la-carte procedures like medial patellofemoral ligament (MPFL) reconstruction enhance stability. In young and active patients, it resolves instability issues and reduces the likelihood of further dislocations with high return to sport rates.
1. Introduction
Patellar instability is a common condition affecting 6 individuals per 100,000, while among adolescents, this rate is notably elevated, being 7 times higher with approximately 30 cases per 100,000 patients.1 Pathoanatomic risk factors encompass trochlear dysplasia, patella alta, femoral and tibial torsional malalignment, lateralized tibial tubercle, and genu valgum.2 Among these factors, trochlear dysplasia has been recognized as the pathoanatomic risk factor exerting the most significant biomechanical influence.3
Trochlear dysplasia involves a lack of concavity in the trochlear groove, resulting in a flat or convex trochlea. It has been demonstrated to elevate patellofemoral pressures, diminish the contact area between the patella and femur, and substantially decrease the force necessary for patellar dislocation within the initial 45° of flexion.4 Trochlear dysplasia is present in more than 80 % of patients with patellar instability.5
The classification of trochlear dysplasia, according to Dejour, primarily relies on lateral radiographs combined with axial imaging. This system categorizes dysplasia into four subtypes: Type A, characterized by a shallow trochlea and the presence of a "crossing sign"; Type B, features a flat trochlea and a supratrochlear spur; Type C, exhibits a double contour due to a hypoplastic medial condyle and a convex trochlea; Type D, the most severe form, which presents a combination of all the aforementioned features.6
Over time, various surgical techniques have been developed to address trochlear dysplasia. Originally described by Masse in 1978 and subsequently refined by Henri Dejour in 1987, sulcus deepening trochleoplasty involves the removal of subchondral bone to enable reshaping of the trochlea into a deeper groove.7,8 Bereiter and Gautier introduced a modification to the Dejour technique for deepening the sulcus by employing a lateral parapatellar approach to elevate a thin (2–3 mm) osteochondral flap. This approach, utilizing a thin flap, eliminates the need for an osteotomy of the articular surface, as the flap is more malleable and allows for greater plastic deformation to conform it to the newly formed groove.9
The aim of this study is to assess the clinical outcomes of sulcus deepening trochleoplasty utilizing the Bereiter technique in conjunction with other surgical procedures targeting the pathoanatomic factors contributing to patellar instability. In literature only few studies investigate the outcomes and return to sport rates following trochleoplasty surgery. Therefore, given its relevance particularly in young and active patients, we believe that further research in this field is needed. Our objective is to perform tailored procedures aiming to establish an à-la-carte surgical approach in order to address individual patient needs effectively in a cohort of young and active patients. We documented pre and post-operatively radiological measurements, as well as post-operative subjective patient improvement and patient reported outcome measures (PROMs), return to sport, complications and re-operation rate following trochleoplasty.
2. Materials and methods
Between January 2019 and February 2022 11 cases of recurrent patellar dislocations underwent surgical management with trochleoplasty. Patients were identified retrospectively from a database of trochleoplasty cases that had been prospectively maintained since 2002 and those who underwent surgery in the last 5 years were selected for the present study. All surgical interventions were executed by the same experienced knee surgeon within a high-capacity institution.
The radiological assessment of patients to determine the eligibility for surgical intervention involved the performance of anteroposterior and lateral knee X-rays, as well as CT and MRI scans.
The radiographic study included the acquisition of knee anteroposterior, lateral, and patella axial views. The preoperative X-rays allowed to measure sulcus angle in axial view as well as trochlear depth and Caton-Deschamps index in true lateral view. The first two measurements are are employed to attain a preoperative assessment of the trochlear size, while the third one is indicative of the patellar height.10,11 (Fig. 1).
Fig. 1.
Pre and post-operative comparison of Xrays in AP and lateral view.
Computed Tomography was performed following the Lyons protocol described by Dejour et al., in 1994.11 This specific protocol that relies on obtaining different sections of the lower limbs which are superimposed allows for the calculation of the following parameters: the tibial tuberosity to trochlear groove (TT-TG) distance, external patellar tilt angle, femoral anteversion and tibial torsion (Fig. 2).
Fig. 2.
Parameters calculated in Computed Tomography performed following the Lyons protocol: tibial tuberosity to trochlear groove (TT-TG) distance (a), external patellar tilt angle (b), femoral anteversion (c) and tibial torsion (d).
Preoperative MRI was utilized to categorize the trochlear dysplasia type (A to D), aligning with the Dejour classification. Furthermore, the lateral trochlear inclination angle was measured in order to assess the trochlear dysplasia, that is identified as the most useful measurement.12
The criteria for study inclusion and indications for trochleoplasty were patients aged between 10 and 25 years, experience of recurrent patellar dislocations with no response to at least 6 months of nonoperative treatment, and a minimum type B trochlear dysplasia according to Dejour et al. As far as the radiological measurements are concerned, the inclusion criteria involved the following thresholds: sulcus angle >145°, trochlear depth < 4 mm, tibial tuberosity to trochlear groove (TT-TG) distance >15 mm, external patellar tilt angle >20°, femoral anteversion <45°, tibial torsion <45° and trochlear inclination angle <11°.
As far as the clinical presentation is concerned, inclusion criteria were persistent knee pain in chronic patellar instability resulting in a reduction or cessation of regular sporting acitivity.
Patients were ineligible for inclusion in the present study in instances of prior lower limb procedures (except MPFL reconstruction), systemic neurological conditions (e.g. cerebral palsy) and cases of dysplastic trochlea type A according to Dejour classification.
All patients were provided with clinical follow-up at 1-3-6 months and afterwards annually. Moreover, control X-rays in standard anteroposterior and lateral view were performed at 1-3-6 months and annually. The post-operative radiological measurements recorded included trochlear depth and Caton-Deschamps Index, since the other pre-operative measurements were obtained through Xrays in axial view, CT scans and MRI which were not repeated after the surgery (Fig. 1).
At the end of follow up patient-reported outcome scores (PROMs) were collected. In particular, Knee Society Score (KSS) was used in order to assesses the knee joint itself and the functional outcome as it evaluates the patient's capacity to walk and climb stairs.13 Furthermore, the Kujala score was obtained as an evaluation system specific for patellofemoral disorders.14 Lastly, the Karnofsky performance status scale was employed to assess the patient's functional status.15
2.1. Surgical technique
The patient is positioned supine on the operating table with a tourniquet at the thigh level, which is used only during the first arthroscopic phase. To begin, via usual portals a knee arthroscopic evaluation is carried out in order to assess the presence of potential femoropatellar cartilage damage as well as of meniscal or associated cartilaginous lesions that can eventually be treated.
At the end of the arthroscopic phase, the knee is flexed at 45° and a lateral incision is made alongside the patella, extending from the superolateral edge to the inferolateral edge, approximately 8–10 mm from the lateral margin. After subcutaneous dissection and exposure of the lateral retinaculum, the latter is incised, taking care not to proximally incise the tendon of the vastus lateralis, and proceeding distally with an incision of the superficial layer only. Dissection of the superficial fibers is then performed posteriorly and laterally to the deeper transverse fibers. The two layers are more easily identifiable at the one-third midpoint of the patella, where the retinaculum is thicker. Once a posterior dissection of 1.5–2 cm is achieved, a second longitudinal incision is made through the deep fibers and the synovial layer, completing the arthrotomy. During closure, the layers are sutured by performing a Z-plasty between the deep and superficial layers.
After exposing the femoral trochlea, a Homan retractor is placed in the medial gutter, and two metallic pins are placed in the femur, later bent to spread the lateral soft tissues. Trochleoplasty according to Bereiter is then performed.16
The periosteum of the entire femoral trochlea is incised, lifting a periosteal flap with a periosteal elevator around the femoral trochlea. The goal of trochleoplasty is to lift an osteocartilaginous flap thin enough to be moldable but not so thin as to include only the cartilage. Sharp osteotomes, preferably dedicated to this procedure, are used. Generally, the osteotomy begins at the superolateral margin of the femoral trochlea with a curved chisel and extends distally and transversely following the anatomy of the trochlea. The level of the osteotomy is a few millimeters below the cartilage, and a compass with adjustable offset (3–5 mm, Arthrex®) can be used as a reference. The osteocartilaginous flap is gradually fashioned using straight and curved chisels until completely lifted from the underlying bone, taking care not to break the distal hinge. At this point, the supra-trochlear bump is removed, and the trochlea is reshaped to achieve a new, deeper, and lateralized groove, correcting the crossing sign and trochlear asymmetry.
Subsequently, using a dedicated mill, the cartilaginous flap with a thickness of 3 mm is sculpted to be fully adaptable to the new trochlea. Once the result is achieved, the flap is fixed by placing 3 PushLock anchors (Arthrex®) in which a 3 mm Vycril tape is slid. The first anchor is placed in the center of the trochlear groove, the second, ensuring proper tensioning of the wire, on the outer margin of the trochlea to stabilize the lateral facet, and the third similarly to stabilize the medial facet. The periosteal layer previously detached is then sutured with absorbable thread in interrupted stitches (Fig. 3, Fig. 4, Fig. 5).
Fig. 3.
Disto-proximal view of the final result after fixation of the flap to the newly shaped trochlea.
Fig. 4.
Proximo-distal view of the final result after fixation of the flap to the newly shaped trochlea.
Fig. 5.
Medio-lateral view of the final result after fixation of the flap to the newly shaped trochlea.
The next step of the procedure is an anteromedialization tibial tubercle osteotomy (TTO) performed through a lateral incision at the tibial tubercle. The insertion of the patellar tendon is identified, and the periosteum and anterior tibial apophysis are incised, exposing the bone surface by detaching the anterior tibial muscle. An osteotomy of the anterior tibial tuberosity is then performed, extending proximally and distally for about 6 cm, obtaining a wedge with a thickness of about 1 cm proximally tapering toward the distal edge of the osteotomy. The author's preference is not to completely interrupt the distal hinge unless a distalization of the anterior tibial tuberosity is also required. The anterior tibial tuberosity is then medialized according to the TT-TG values found in the diagnostic phase, generally not exceeding 1 cm, and synthesized with 2 bicortical screws, sometimes using washers.
The third phase of the procedure involves the reconstruction of the medial patellofemoral ligament, performed functionally without bony tunnels or anchor use, using a gracilis graft or fiber tape. The reconstruction is carried out through two mini-incisions: the first at the medial edge of the patella, exposing the medial retinaculum (1st layer). The retinaculum is then incised, identifying the oblique vastus medialis. Using a curved clamp, the layer beneath the vastus medialis obliquus is developed towards the medial epicondyle. At this level, near the subcutaneous prominence of the clamp, a second mini-incision is made. With the clamp, a loop is retrieved, which will be used as a shuttle. The periosteum of the patella is incised, submining two small periosteal and tendinous pulleys through which the graft, basted at the two ends with a thread for traction, is passed. The graft is then passed through the loop described earlier and pulled up to the level of the medial epicondyle. It is then fixed at the Schottle point, identified under fluoroscopy control, using a tunnel with a distoproximal and posteroanterior direction, with a diameter parameterized to the doubled graft width (usually a 6 mm X 35 depth drill). After placing the graft in the tunnel, isometry is verified, followed by fixation with an absorbable screw with the knee flexed to approximately 70° (between 60 and 90°). The ligament should not be tensioned or "medialized" to the patella, aiming only to counteract lateralization. After fixation, the graft is reinforced at the patella with 2 non-absorbable stitches, and layer-by-layer suturing is performed.
2.2. Post-operative care
The post-operative care entail for the first four weeks the use of rigid knee brace with weight-bearing as tolerated as well as physiotherapy including manual mobilization of the knee within a range of motion of 0–30°, manual patellar mobilization and exercises of isometric quadriceps strengthening, gluteal activation and muscular pump.
At 60 days post-surgery, the provided instructions are the removal of the knee brace, progressive flexion of the knee with 0–90° as a target, gradual cessation of crutches, still avoiding exercises against resistance and stairs. From 60 to 90 days after surgery complete range of motion is allowed, as well as muscular strengthening and postural exercises. After 90 days gradual resumption of activities and preparation for return to sports if previously practiced are allowed.
2.3. Statystical analysis
Categorical variables were delineated through frequency and percentage distributions, while continuous variables were elucidated using the mean and standard deviation (SD).
3. Results
11 patients who underwent surgical trochleoplasty procedure between January 2019 and February 2022 were enrolled in the present study. All patients were available for evaluation at final follow up.
Demographic information at the time of surgery for all 11 analyzed patients is presented in Table 1. There were 7 female participants and 4 male participant, with an mean age of 17.8 years (ranging from 15 to 25; standard deviation (SD) 0.7). In 6 patients, the operated knee was the right side, in 5 was the left side.
Table 1.
Baseline demographics.
| Patient population | Number | % |
| Total no. | 11 | 100 |
| Available |
11 |
100 |
|
Sex Number % |
Number |
% |
| Male | 4 | 36.4 |
| Female |
7 |
63.6 |
|
Age at operation |
Average (Y) | SD |
| 17.8 |
0.7 |
|
|
FU |
Average (M) | SD |
| 43 |
26.9 |
|
|
BMI |
Average |
SD |
|
Side Number % |
Number |
% |
| Left | 13 | 44.8 |
| Right | 16 | 55.2 |
Out of the 11 patients, 2 had experienced prior surgical MPFL reconstruction on the corresponding knee.
As far as the radiological measurements are concerned, the values calculated pre-operatively are presented in Table 2. Taking into consideration the measurements derived from the radiographs, the mean values calculated were 152.5° for sulcus angle (SD 10.6), 3.4 mm for trochlear depth (SD 1.2) and 1.2 for Caton-Deschamps index (SD 0.1). The implementation of the Lyonese protocol on CT scans allowed us to achieve the following mean values: 17.5 mm for tibial tuberosity to trochlear groove (TT-TG) distance (SD 2.1), 6.8° for trochlear inclination angle (SD 1.9), 18° for external patellar tilt angle (SD 4.2), 11.5° for femoral anteversion (SD 2.1), 32° for tibial torsion (SD 2.8).
Table 2.
Preoperative radiological measurements.
| X-rays measurements | ||
| Sulcus angle |
Average (°) |
SD |
| 152.5 |
10.6 |
|
|
Trochlear depth |
Average (mm) |
SD |
| 3.4 |
1.2 |
|
|
Caton-Deschamps index |
Average |
SD |
| 1.2 |
0.1 |
|
| CT scan measurements | ||
|
TT-TG |
Average (mm) |
SD |
| 17.5 | 2.1 | |
|
External patellar tilt angle |
Average (°) |
SD |
| 6.8 |
1.9 |
|
|
Femoral anteversion |
Average (°) |
SD |
| 11.5 |
2.1 |
|
|
Tibial torsion |
Average (°) |
SD |
| 32 | 2.8 | |
In Table 3 the post-operative radiological measurements are displayed. As mentioned before, the post-operative radiological follow up included only Xrays in anteroposterior and lateral view, therefore the only mean post-operative measurements obtained were: 5.5 mm for trochlear depth (SD 1.9) as compared to 3.4 mm pre-operatively (p.value 0.05) and 0.9 for Caton-Deschamps index (SD 0.1) as compared to 1.2 preoperatively (p.value 0.01).
Table 3.
Pre and post-operative radiological measurements.
| Mean mm (SD) preop | Mean mm (SD) postop | p.value | |
|---|---|---|---|
| Trochlear depth | 5.5 (0.2) | 3.4 (1.2) | 0.05 |
| Caton-Deschamps index | 0.9 (0.1) | 1.2 (0.1) | 0.01 |
All patients were evaluated for a minimum of 2 years following surgery, with an average follow up of 43 months (ranging from 40 to 62, standard deviation (SD) 26.9).
Additional surgery was performed concurrently during the same procedure as trocheoplasty on the corresponding knee. Every patient underwent concurrent tibial tuberosity transposition as well (100 %), as a result of the radiographic indications based on the Caton-Deschamps index and TT-TG distance. In 9 cases, an additional MPFL reconstruction was also performed (81,8 %), due to the fact that these are the two abovementioned patients who had previously undergone MPFL reconstruction. Ultimately, two patients also underwent division of the external alar ligament (18,2 %). The indication for performing this procedure was, from a radiographic standpoint, a tilt angle value exceeding 20°.
Regarding the outcomes of PROMs administered to the patients at final follow up showed favorable clinical as well as functional results, which can be visualized in Table 4. The mean value of KSS was 80.5 (ranging from 53 to 89; SD 12.6). The mean Kujala score was 88.3 (ranging from 60 to 99; SD 15.2). Lastly, Karnofsky performance status scale showed an average value of 88.8 (ranging from 70 to 100; SD 15.2).
Table 4.
PROMs results at final follow up.
| SCORE | Average | SD | Range |
|---|---|---|---|
| KSS | 80.5 | 12.6 | 53–89 |
| Kujala score | 88.3 | 15.2 | 60–99 |
| Karnofsky performance scale | 88.8 | 9.9 | 70–100 |
As far as the return to sport rate is concerned, 10 patients of this cohort were active in sport before surgery, while only one was not sportive for reasons other than the patellar pathology (90,9 %). All the 10 sportive patients claimed to have resumed sports activities at the same level when interviewed at final follow up.
As for the need for secondary surgical interventions, in 3 cases there was an indication for the removal of screws from the transposition of the tibial tuberosity due to intolerance (27,3 %).
4. Discussion
The present study illustrates that sulcus-deepening trochleoplasty performed with the Bereiter technique constitutes an effective and dependable procedure for individuals experiencing patellar instability due to severe trochlear dysplasia. Valuable perspectives on the application of trochleoplasty and associated procedures are offered, despite the limited number of patients investigated. Within this group of 11 knees treated at a single institution, no cases of recurrent lateral patellar instability were observed during follow-up. Subjective clinical outcome assessments revealed promising results in KSS and Kujala scores, as well as in Karnofsky performance status scale. The sole indication for a secondary surgical procedure was intolerance to the screws and its consequent removal in three cases (37.5 %).
Patellofemoral instability is a multifactorial condition and therefore several procedures have been reported in literature for treating this condition. Trochlear dysplasia plays a significant role in causing patellofemoral instability and should be addressed by surgical correction.17
Trochleoplasty rationale is to change the shape of the trochlea and improve patellofemoral congruency for stabilizing the patella. There are alternative methods to perform deepening trochleoplasty beyond the "thick shell" osteotomy, also known as the DeJour method.8 One such method, advocated by Schöttle, is the Bereiter "thin flap" approach, which involves creating a flexible osteochondral shell which is then reshaped and secured using absorbable suture tape.9
Of particular importance are the radiographic parameters examined in preoperative radiological investigations through X-rays, CT and MRI to develop a patient-specific surgical plan.
Since the variability in the pathoanatomical pattern of patellofemoral instability, the treatment should be à-la-carte and as a consequence the abovementioned techniques are often performed in combination with other corrective procedures.
In 9 patients included in the present study (81,8 %), an additional surgical procedure of medial patellofemoral ligament (MPFL) reconstruction was performed, as when the patella dislocates, it causes a traumatic injury to it. This procedure has positive biomechanical benefits, since when the trochlear groove is restored, improved patellar tracking can be observed during flexion, but as the knee approaches full extension, the stabilizing effect of the MPFL is still lacking.18
When considered alone MPFL reconstruction in cases of trochlear dysplasia may be insufficient and is reported to have high rate of re-dislocation.19
However, when combined with the restore of the trochlear groove achieved with the trochleoplasty procedure, MPFL reconstruction gives additional stability in particular near full knee extension.
A meta-analysis by Ren et al. that considered 6 studies with a total of 192 knees comparing trochleoplasty isolated and combined with MPFL reconstruction showing a higher increase in Kujala score as well as lower re-dislocation and re-operation rates when the combination of techniques is being used.20
In another prospective study on 18 knees published by Banke et al., the results of combined trocheoplasty and MPFL reconstruction were recorded showing satisfactory clinical outcomes and comparable to our results in terms of post-operative Kujala score (mean 87.9).
In all the patients enrolled in the present study a concomitant anteromedialization tibial tuberosity osteotomy was performed (100 %). Although trochleoplasty allows a lateralization of the trochlear groove that can effectively decrease the TT-TG distance up to 10 mm, further reduction can be achieved only adding TTO.10,20 Using a tibial tubercle osteotomy to address mal-tracking related to severe dysplasia has been suggested as a safer method to enhance tracking compared to performing only trochleoplasty.17 Tan et al. published a study on 21 patients treated with combined tibial tubercle transfer, medial patellofemoral ligament reconstruction, trochleoplasty and lateral release for patellofemoral instability showing a statistically significant increase in Kujala score comparable to the results found in the present study.21
The majority of patients requiring this operation face challenges participating in sports due to severe patellofemoral instability. In the sample examined for this study, 10 out of 11 patients were active in sports (90.9 %). After restoring stability through surgery, all these 10 patients were able to resume either an active occupation or competitive sports post-operatively, although the study did not categorize patients by the level of competition.
In literature return to sport rates after trochleoplasty and other concomitant procedures addressing patellofemoral instability may vary, but there is agreement in concluding that the majority of operated patients return to sports.
An interesting study on 111 patients who underwent trochleoplasty and other concomitant patellar-stabilizing procedures stated that two-thirds of the patients resumed their preoperative level of activity or surpassed it but the probability of returning to the same activity level was notably greater in the low-level activity group compared to the high-level activity group.22
Nelitz et al. published a study on 23 patients who underwent combined thin flap trochleoplasty and MPFL reconstruction highlighting that 17 of them returned to sport at or above their level prior to surgery.23 Similar results were observed by Ntagiopoulos and Dejour et al. after performing thick shell trochleoplasty, with 87 % of their patients resuming their prior activities post-surgery.24
While literature regarding trochleoplasty suggests that the post-operative enhancement of stability can be anticipated, the occurrence of pain post-surgery is less certain and might potentially escalate.
A study on 42 patients who underwent sulcus-deepening trochleoplasty according to Bereiter technique conducted by Fucentese et al. concluded that the pre-operative classification of dysplasia is indicative of clinical outcomes, with types B and D according to Dejour demonstrating notably superior outcomes in terms of Kujala score and residual pain in sport activities.25 In our patient cohort, there were 8 cases classified as type B and 3 cases classified as type D. Remarkably, we observed favorable outcomes in these cases, which aligns with the findings of the aforementioned study.
Moreover, in our sample of patients residual pain was individualized as due to the intolerance to the screws and as a consequence all the 3 patients who experienced post-operative pain found relief of the symptoms after surgical removal of the screws.
Limitations of the present study include the small sample size due to rarity of the procedure and the short term follow up. However, the main strength of the study lies in the demonstration of promising results in terms of PROMs and return to sport which should suggest a wider utilization of this procedure in addressing trochlear dysplasia and should highlight the importance of studies with longer follow up to confirm the promising results over a longer period of time.
5. Conclusions
Trochleoplasty is highly efficient in addressing trochlear dysplasia in patellofemoral instability in young and active patients. When combined with targeted additional procedures developing a customized treatment plan based on the individual patient's pathoanatomic factors, it can successfully resolve patients' instability issues and reduce the likelihood of further dislocation episodes. The results obtained in this limited patient cohort need to be validated on a larger scale through studies involving more extensive patient populations.
Conflict of interest
All authors declare no conflict of interest related to the present study.
Funding
No funding was received for the present study.
Ethical approval
Ethical committee approval was not sought for the present study since it is a retrospective analysis of the outcomes of a surgical technique which is routinely performed in our center.
Informed consent
All patients signed an informed consent for the surgical procedure and for publication of the data.
Credit author statement
Authors’ contribution: AM, LA and LM designed and were responsible for the manuscript. All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by LA, AM and RS. The first draft of the manuscript was written by LA, AM and FN. FB and SMPR supervised the study, AM and LA were responsible for clinical data All authors read and approved the final manuscript.Disclorsures: nothing to disclose for the present study
Declaration of competing interest
None of the authors of the present study have interests to declare.
Acknowledgements
none.
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