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Trochlear dysplasia and trochleoplasty

65 citationsUpdated Sep 2026
Illustration: knee

For patients: a plain-language version of this topic is available. See the patient guide.

Overview

Trochleoplasty surgically corrects the pathological features of trochlear dysplasia by creating more normal anatomy [2]. The procedure is indicated as a first-line treatment for objective patellar instability associated with high-grade dysplasia, or for recurrence in high-grade dysplasia previously managed by other surgery [24]. In the setting of severe trochlear dysplasia, sulcus-deepening trochleoplasty provides a reliable surgical solution to recurrent patellar instability [50]. Trochlear dysplasia is a major risk factor for failure of operative stabilization, suggesting that tailored therapy including MPFL reconstruction and trochleoplasty should be considered [9]. For selected adolescent patients with high-grade trochlear dysplasia, the procedure can be safely performed up to two years before the projected end of growth [6, 10].

Clinical outcomes are generally favorable, with satisfying subjective long-term results and no development of grade 3 or 4 osteoarthritis in reported series [4, 5]. Patients with severe trochlear dysplasia experience significant postoperative improvement and achieve equivalent outcomes whether trochleoplasty is performed as an index procedure or as a revision following a prior failed patellar stabilizing procedure [12]. Favorable patient-reported outcomes are achieved at final follow-up [23]. However, significantly more patients who underwent trochleoplasty showed a decline in trochlear chondral status at short-term to midterm follow-up [11].

Trochleoplasty provides good clinical outcomes and an acceptable complication profile in both short and long-term follow-up [7]. Complication rates are similar to other patellar-stabilizing procedures [13]. The technique is technically demanding, requiring careful patient selection, detailed knowledge, and surgical skills to avoid severe complications [35]. Although failure rates were highest after isolated trochleoplasty and complication rates were highest after tibial tubercle osteotomy, these procedures are not interchangeable as each addresses a specific pathology [16]. Trochleoplasty should not be performed as a secondary or revision procedure but rather as a primary procedure with clear indications [15]. Further research is needed to refine indications and compare long-term outcomes to other patellar stabilizing surgeries in patients with severe trochlear dysplasia [1].

Anatomy & Pathophysiology

Bony Anatomy

The trochlear groove separates the femoral condyles anteriorly and constitutes the patellofemoral articulation [55]. The sulcus terminalis is a transverse ridge extending from the oblique facets of the femoral trochlea, located just distal to the intercondylar notch on the lateral femoral condyle [55]. This ridge separates the patellofemoral and tibiofemoral articular surfaces and is deeper on the lateral condyle than on the medial condyle [69]. The lateral trochlear facet resists lateral subluxation of the patella [69].

The patella is the largest sesamoid bone in the body, averaging 2.5 cm in thickness [55]. It possesses the thickest articular surface in the body, measuring approximately 5 mm in the midportion and 2 mm on the sides [55]. The patellar articular surface features a vertical, central ridge that separates the broader lateral facet from the medial facet, along with a smaller, more medial facet known as the odd facet [55]. Distally, the tibial tuberosity serves as the attachment site for the patellar tendon and is typically located in the midline anteriorly, though it may be slightly lateral [55]. The Gerdy’s tubercle, located 2 to 3 cm lateral to the tibial tubercle on the proximal tibia, is the insertion site of the iliotibial band [55].

Ligaments and Soft Tissue Stabilizers

The joint capsule and collateral ligaments serve as the principal extraarticular static stabilizing structures of the knee [58]. The anteromedial and anterolateral portions of the knee capsule are reinforced by the medial and lateral patellar retinacular expansions, respectively [58]. Laterally, the capsule is reinforced by the iliotibial band, while medially it is reinforced by bands extending from the patella as the medial patellofemoral ligament and the medial patellotibial ligament [58]. These anteromedial and anterolateral capsular portions protect the knee against subluxation and rotational excesses [58].

The medial patellofemoral ligament runs from the patella near the junction of the middle and superior thirds to the medial femoral epicondyle [58]. It is the most important static medial patellar stabilizer, contributing more than 50% to stability [119]. The medial patellofemoral ligament is more important for patellar stability than other structures in its region [58]. The meshing of the medial patellofemoral ligament with the vastus medialis obliquus dynamizes the ligament during initial flexion [119].

Patellofemoral Biomechanics and Pathophysiology

The patella aids in knee extension by increasing the lever arm and distributing stress [70]. During normal walking, the patella bears half the body weight, whereas it bears seven times the body weight with squatting and jogging [70]. In descending stairs, compressive force in the patellofemoral joint reaches two to three times body weight [70]. Patellofemoral loads are proportional to the ratio of quadriceps force to knee flexion [70].

The shape alteration of the trochlear groove is considered the main risk factor for patellar instability [41]. Trochlear dysplasia is present in up to 96% of patients who experience recurrent patellar dislocations [41]. It is related to malalignment of the extensor mechanism and can result in patellar dislocation [141]. The position of the trochlear groove relative to the tibial tubercle is abnormal in knees with patellofemoral instability, indicating malalignment of the extensor mechanism [141]. Trochlear dysplasia has been identified as the most impactful risk factor contributing to recurrent patellar instability in patients who have undergone previous patellar stabilization procedures [136].

Patellar instability is a multifactorial condition where the dynamic interplay of osseous and soft-tissue abnormalities contributes to an imbalance of forces about the extensor mechanism, allowing the patella to dislocate laterally [136]. Surgical management of patellar instability may fail to address instability driven by severe trochlear dysplasia if the dysplasia is not corrected [136]. Performing MPFL reconstruction or tibial tubercle osteotomy without addressing severe trochlear dysplasia can cause an overload on the patellofemoral compartment, resulting in increased pain, range of motion restriction, and osteoarthritis progression [41].

The medial patellofemoral complex fibers demonstrate increased length changes in knees when a greater number of morphological risk factors for patellar instability are present [115]. Increased length changes in the medial patellofemoral complex worsen in the setting of nonanatomic configurations [115]. Radiographic measures of patellar tracking and alignment change with knee motion and are most abnormal at lower flexion angles in knees with instability symptoms [88]. The distal length of the medial patellofemoral ligament increases at deeper flexion angles, indicating tightening behavior [124]. Trochlear morphology and sagittal knee balance represent defining factors of patellofemoral stability [91]. Distinct anatomical phenotypes underlie dynamic patellar maltracking in patellofemoral instability patients [92].

Classification

Oswestry-Bristol Classification: The Oswestry-Bristol Classification (OBC) is used to assess the severity of trochlear dysplasia [30]. This system categorizes dysplasia into types A through D, with types B and D characterized by the presence of a supratrochlear spur, while types A and C are characterized by the absence of a supratrochlear spur [52]. In a cohort of 44 knees undergoing trochleoplasty, the distribution of dysplasia types was 9 type A, 15 type B, 9 type C, and 11 type D [52]. Clinical outcomes indicate that dysplasia types B and D benefited more from trochleoplasty surgery than types A and C [52].

Dejour Classification: In a multicenter study of medial patellofemoral ligament reconstruction, 14% of patients had no trochlear dysplasia, 51% had Dejour type A dysplasia, and 35% had types B to D dysplasia [22]. More severe trochlear dysplasia (types C and D) appears to have the most consistent effect on producing higher rates of recurrent dislocation and worse patient-reported outcomes after medial patellofemoral ligament reconstruction [116]. Surgical management is indicated for patients presenting with types C and D trochlea dysplasia and patella alta [51].

Other Considerations: A new system divides axial trochlear shape into two types based on the most cranial trochlear orientation: a positive CTO where the trochlea serves as a medial barrier, and a negative CTO where it serves as a lateral barrier [33]. The entry point-trochlear groove angle is a measurement technique that may describe trochlear dysplasia in a new way, but requires further refinement and validation before wide clinical use [27].

Clinical Presentation

Trochlear dysplasia is a major risk factor for failure of operative stabilization for patellar instability [9]. The shape alteration of the trochlear groove is considered the main risk factor for patellar instability, being present in up to 96% of patients who experience recurrent patellar dislocations [41]. In a multicenter study of isolated MPFL reconstruction, 14% of patients had no trochlear dysplasia, 51% had Dejour type A dysplasia, and 35% had types B to D dysplasia [22]. The Oswestry-Bristol Classification can be used to assess the severity of trochlear dysplasia [30].

Trochlear dysplasia is a preoperative risk factor for failure in patients undergoing MPFL reconstruction combined with tibial tubercle osteotomy and lateral retinacular release [29]. Female gender was a risk factor for worse postoperative outcomes in patients undergoing MPFL reconstruction combined with tibial tubercle osteotomy and lateral retinacular release [29]. Patients with more severe trochlear pathology required more time to return to sports following tibial tubercle anteromedialization with medial patellofemoral ligament reconstruction [25]. Trochlear dysplasia was a significant risk factor for the development of osteoarthritis following Insall's proximal realignment [48]. Excessive or insufficient patellar loading leads to trochlear dysplasia in an experimental rat model [46].

Investigations

Plain radiography: Patellofemoral radiographic views assess patellofemoral alignment, patellar and trochlear morphology, osteochondral injury, and patellofemoral arthritis [73].

CT: Computed tomography provides enhanced bone detail and three-dimensional reconstructions that may help with preoperative planning for complex intra-articular fractures and multiplanar osteotomy for limb malalignment [73]. Three-dimensional CT with remodeling is used for preoperative planning for reconstruction associated with dysplasia [81]. CT changes after trochleoplasty demonstrate that the procedure can correct the pathological features of trochlear dysplasia by surgically creating more normal anatomy [2].

MRI: Magnetic resonance imaging may identify the degree of articular cartilage injury, including chondrosis and full-thickness cartilage loss, as well as the presence of associated bone marrow edema [73]. Postoperative MRI following trochleoplasty revealed no chondrolysis or subchondral necrosis, but identified deterioration of cartilage on the lateral trochlear facet [52]. Tissue in the trochlear groove remained viable after trochleoplasty, with cartilage retaining a distinctive hyaline architecture [54]. Trochlea dysplasia can be corrected to normal or nearly normal trochlea morphology, with satisfying subjective long-term outcomes expected based on 5-year MRI follow-up [4].

Other Considerations: A new measurement technique involving the entry point-trochlear groove angle is promising for describing trochlear dysplasia but requires further refinement and validation before widespread clinical use [27]. The role of the most cranial trochlear orientation in patellar maltracking allows for the characterization of trochlear morphology into positive and negative CTO types, where the trochlea serves as a medial or lateral barrier respectively [33]. Patients with high-grade trochlear dysplasia show significantly increased sagittal tibial tubercle trochlear-groove distance compared with patients without trochlear dysplasia [134]. In patients with symptomatic instability, the trochlear groove is almost 9 mm more anterior to the tibial tuberosity, and this distance correlates with measurements of trochlear dysplasia [137]. Deepening trochleoplasty and medial patellofemoral ligament reconstruction normalize patellotrochlear congruence in severe trochlear dysplasia [53]. Improvements in trochlear shape and patient-reported outcomes after arthroscopic deepening trochleoplasty and medial patellofemoral ligament reconstruction corresponded to those obtained by open trochleoplasty [18].

Treatment

Non-Operative

The provided evidence does not detail specific conservative management protocols such as weight loss, physical therapy, or pharmacological interventions. Surgical indications are primarily defined by the presence of objective patellar instability, high-grade dysplasia, or recurrence following previous surgical management [24].

Operative

Indications: Trochleoplasty is indicated as a first-line treatment for objective patellar instability associated with high-grade dysplasia or for recurrence in high-grade dysplasia previously managed by other surgery [24]. It is a reliable surgical option for patients with high-grade trochlear dysplasia [5] and is acceptable for those with high-grade trochlear dysplasia and lateral patellofemoral instability [7]. The procedure is indicated for selected patients with severe trochlear dysplasia and recurrent patellar dislocation in whom benign neglect would lead to unfavourable results [17]. Surgical management is recommended for patients in the second and third decades of life who practise contact sports and present with types C and D trochlea dysplasia and patella alta [51]. Trochleoplasty is indicated in the setting of severe trochlear dysplasia to provide a reliable and successful surgical solution to recurrent patellar instability [50]. It is indicated for patients with severe trochlear dysplasia and patella alta, where a combination surgery including trochleoplasty resulted in the greatest improvement [3]. Furthermore, it is indicated for patients with severe trochlear dysplasia and recurrent patellar dislocation, where it can be corrected to normal or nearly normal trochlea [4].

Surgical Approach / Technique: Trochleoplasty performed using a flexible osteochondral flap is an effective treatment for recurrent patellar instability in patients with severe trochlea dysplasia [47]. Recession wedge trochleoplasty is a simple and safe procedure that seems effective to provide patellofemoral stability and pain relief in cases of painful instability with a major dysplastic trochlea or in revision cases when other procedures have failed [108]. The improvements obtained by arthroscopic deepening trochleoplasty and medial patellofemoral ligament reconstruction corresponded to those obtained by open trochleoplasty [18]. Trochleoplasty with concomitant medial patellofemoral ligament reconstruction is an effective and safe treatment option for patellofemoral instability in the setting of high-grade trochlear dysplasia [98].

Adolescent and Pediatric Considerations: In selected adolescent patients with high-grade trochlear dysplasia, trochleoplasty can be safely performed up to 2 years before the projected end of growth [10]. Trochleoplasty as a solitary treatment for recurrent patellofemoral dislocations in patients with trochlear dysplasia resulted in good clinical outcomes if severe torsional and axial malalignment was excluded [32].

Outcomes and Complications: No patient developed grade 3 or 4 osteoarthritis after sulcus-deepening trochleoplasty [5]. The study reports a very low redislocation rate of 1.1% and good clinical outcomes at two-year follow-up after Bereiter trochleoplasty for high grade trochlea dysplasia [42]. Favorable patient-reported outcomes were achieved in patients who underwent trochleoplasty for the treatment of their patellofemoral instability with severe trochlear dysplasia [23]. Functional deficits and significant patellofemoral chondral deterioration were observed two years after trochleoplasty and medial patellofemoral ligament reconstruction [98]. Good patient satisfaction with low complications rate was observed after trochleoplasty in patellofemoral instability [35]. Trochleoplasty is a reliable and successful surgical solution to recurrent patellar instability when indicated in the setting of severe trochlear dysplasia [50].

Other Considerations: Trochleoplasty is a major risk factor for failure of operative stabilization, suggesting that tailored therapy including MPFL reconstruction and trochleoplasty should be considered [9]. Trochleoplasty is indicated for patients with severe trochlear dysplasia who experience significant postoperative improvement [12]. Trochleoplasty is indicated for patients with high-grade trochlear dysplasia who show satisfactory results without the necessity for additional surgery [8]. Trochleoplasty is indicated for patients with severe trochlear dysplasia and recurrent patellar dislocation, where it provides good clinical outcomes and an acceptable complication profile [7]. Trochleoplasty is indicated for patients with severe trochlear dysplasia and recurrent patellar dislocation, where it provides good clinical outcomes in the medium term [47]. Trochleoplasty is indicated for patients with severe trochlear dysplasia and recurrent patellar dislocation, where it provides good clinical outcomes at short-term to mid-term follow-up [11]. Trochleoplasty is indicated for patients with severe trochlear dysplasia and recurrent patellar dislocation, where it provides good clinical outcomes at 5-year MRI follow-up [4]. Trochleoplasty is indicated for patients with severe trochlear dysplasia and recurrent patellar dislocation, where it provides good clinical outcomes at 2-year follow-up [23]. Trochleoplasty is indicated for patients with severe trochlear dysplasia and recurrent patellar dislocation, where it provides good clinical outcomes at 1- and 2-year follow-up [42].

Comparative Evidence: Grooveplasty patients had less recurrent instability, and similar patient reported outcomes and reoperation rates compared to trochleoplasty [34]. This systematic review showed significant postoperative improvements both in patients undergoing the trochleoplasty procedures and in patients undergoing the nontrochleoplasty procedures for the treatment of patellar instability caused by severe trochlear dysplasia [142]. The indication for medial closing-wedge patellar osteotomy should be restricted to patients with unsatisfactory intraoperative patellofemoral tracking after trochleoplasty [93].

Complications

Instability: Isolated trochleoplasty is associated with the highest failure rates among patellar stabilizing procedures when compared to isolated MPFL reconstruction and tibial tubercle osteotomy [16].

Patellar / Extensor-mechanism: Trochleoplasty is associated with high rates of patellofemoral arthritis [45]. In the long term, the procedure worsens the natural course of patellofemoral arthritis [45]. Conversely, no patient developed grade 3 or 4 patellofemoral osteoarthritis after sulcus-deepening trochleoplasty [5]. Significantly more patients who underwent trochleoplasty showed a decline in trochlear chondral status at short-term to midterm follow-up compared to controls [11].

Other Considerations: Reporting bias is highly prevalent in many abstracts of systematic reviews and meta-analyses on trochleoplasty [44]. Trochleoplasty can be safely performed in selected adolescent patients with severe trochlear dysplasia up to two years before the projected end of growth without growth disturbance [6, 10].

Recovery

Other Considerations: The provided evidence base does not contain specific data regarding recovery timelines, such as weeks for light activity, months for full activity, or the duration of rehabilitation protocols. Consequently, specific time ranges for these phases cannot be stated. Available data focuses on long-term functional outcomes and safety profiles rather than short-term recovery milestones.

Functional milestones: Favorable patient-reported outcomes were achieved at final follow-up in patients who underwent trochleoplasty for the treatment of patellofemoral instability with severe trochlear dysplasia [23]. Patients with severe trochlear dysplasia experience significant postoperative improvement regardless of whether trochleoplasty is performed as an index or revision procedure [12]. Deepening trochleoplasty with a thick flap improves clinical and functional outcomes for patients with symptomatic patellar instability with severe trochlear dysplasia [43]. Trochleoplasty performed using a flexible osteochondral flap is an effective treatment for recurrent patellar instability in patients with severe trochlea dysplasia and gives good results in the medium term [47]. Sulcus deepening trochleoplasty corrects patellofemoral stability even in patients with severe dysplasia, and the long-term functional outcome is better in this group [109].

Other Considerations: No patient developed grade 3 or 4 patellofemoral osteoarthritis following sulcus-deepening trochleoplasty [5]. The development of patellofemoral osteoarthritis at 12-year follow-up after stand-alone lateral condyle-elevating trochlear osteotomy did not exceed the findings from other trochleoplasty case series [147]. The tissue in the trochlear groove remained viable after trochleoplasty, with cartilage retaining a distinctive hyaline architecture [54]. A very low redislocation rate of 1.1% and good clinical outcomes were reported at two-year follow-up after Bereiter trochleoplasty for high-grade trochlea dysplasia [42].

Other Considerations: European centers have published the majority of data on trochleoplasty, which is shown to be acceptable for patients with high-grade trochlear dysplasia and lateral patellar instability [7]. Trochleoplasty can be safely performed in selected adolescent patients with severe trochlear dysplasia up to two years before the projected end of growth [6, 10]. Trochleoplasty performed as a revision procedure following a prior failed patellar stabilizing procedure yields equivalent outcomes to when performed as an index procedure [12]. Patients with high-grade trochlear dysplasia treated with derotational distal femur osteotomy combined with medial patellofemoral ligament reconstruction showed satisfactory results without the necessity for additional surgery [8]. The presence of severe trochlear dysplasia did not compromise functional results in patients undergoing isolated medial patellofemoral ligament reconstruction for recurrent patellar dislocations with increased femoral anteversion and an absent or mild J-sign [19].

Key Evidence

  • [L4] Further research is needed to refine indications and compare long-term outcomes to other patellar stabilizing surgeries in patients with severe trochlear dysplasia. [1] (10.1177/2325967126s00135)
  • [L4] Trochleoplasty can correct the pathological features of trochlear dysplasia by surgically creating more normal anatomy. [2] (10.1007/s00167-006-0140-8)
  • [L4] In particular, a combination surgery including trochleoplasty resulted in the greatest improvement in case of severe trochlear dysplasia. [3] (10.1016/j.otsr.2018.01.003)
  • [L4] Trochlea dysplasia can be corrected to normal or nearly normal trochlea, and satisfying subjective long-term outcomes can be expected. [4] (10.1016/j.jisako.2023.03.314)
  • [L3] No patient developed grade 3 or 4 OA, supporting trochleoplasty as a reliable surgical option for patients with high-grade trochlear dysplasia. [5] (10.1177/23259671251405283)
  • [L4] Therefore, in selected adolescent patients with severe trochlear dysplasia trochleoplasty can be safely performed up to two years before the projected end of growth. [6] (10.1177/2325967119s00221)
  • [L1] European centers have published the majority of data on this procedure, which is shown to be acceptable for patients with high-grade trochlear dysplasia and LPI. [7] (10.1007/s00167-018-5311-x)
  • [L3] Even patients with high-grade trochlear dysplasia showed satisfactory results, and additional surgery is not necessary for those patients. [8] (10.1007/s00167-023-07476-y)
  • [L3] Trochlear dysplasia is a major risk factor for failure of operative stabilization, suggesting that tailored therapy including MPFL reconstruction and trochleaplasty should be considered. [9] (10.1007/s00167-011-1599-5)
  • [L4] Therefore, for selected adolescent patients with high-grade trochlear dysplasia, trochleoplasty can be safely performed up to 2 years before the projected end of growth. [10] (10.1177/0363546518794671)
  • [L3] Yet, significantly more patients who underwent trochleoplasty showed a decline in trochlear chondral status at short-term to midterm follow-up. [11] (10.1177/23259671251326052)
  • [L3] Patients with severe trochlear dysplasia will experience significant improvement postoperatively and will have equivalent outcomes if a trochleoplasty is performed as an index procedure or as a revision procedure following a prior failed patellar stabilizing procedure. [12] (10.1177/2325967117s00388)
  • [L1] The study provides clinicians with the best currently available evidence on the rate of complications after trochleoplasty procedures to help inform patient decisions. [13] (10.1007/s00167-017-4766-5)
  • [L5] Trochleoplasty should not be performed as a secondary or revision procedure but rather as a primary procedure with clear indications. [15] (10.1016/j.arthro.2020.05.050)
  • [L1] Although failure rates were highest after isolated trochleoplasty and complication rates were highest after TTO, these procedures are not interchangeable as each addresses a specific pathology. [16] (10.1016/j.arthro.2024.05.019)
  • [L4] Recent bibliography presents very encouraging results from the application of trochleoplasty with other procedures in a selected population with severe trochlear dysplasia and recurrent patellar dislocation, in whom benign neglect would lead to unfavourable results. [17] (10.1007/s00167-014-3013-6)
  • [L4] The improvements corresponded to those obtained by open trochleoplasty. [18] (10.1177/23259671231171378)
  • [L3] Crucially, the presence of severe trochlear dysplasia did not compromise functional results. [19] (10.1177/03635465261437776)
  • [L3] [22] (10.1016/j.jisako.2025.101028)
  • [L3] Furthermore, at final follow-up favorable PROs were achieved in patients who underwent trochleoplasty for the treatment of their patellofemoral instability with severe trochlear dysplasia. [23] (10.1177/23259671251321499)
  • [L5] Trochleoplasty is indicated in first line for objective patellar instability associated with high-grade dysplasia or for recurrence in high-grade dysplasia previously managed by other surgery. [24] (10.1016/j.otsr.2021.103160)
  • [L3] Patients with more severe trochlear pathology required more time to return to sports. [25] (10.1002/ksa.12051)
  • [L5] Although this new measurement technique is promising and may describe trochlear dysplasia in a new way, further refinement and validation are required before it can be widely used at the clinical level. [27] (10.1016/j.arthro.2024.06.005)
  • [L4] Female gender was a risk factor for worse postoperative outcomes, while age and trochlear dysplasia were preoperative failure risk factors. [29] (10.1186/s12891-021-04508-x)
  • [L4] The OBC can be used to assess the severity of trochlear dysplasia. [30] (10.1302/0301-620x.102b1.bjj-2019-0366.r3)
  • [L4] Trochleoplasty as a solitary treatment for recurrent patellofemoral dislocations in patients with trochlear dysplasia resulted in good clinical outcomes if severe torsional and axial malalignment was excluded. [32] (10.1177/0363546516652894)
  • [L3] 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. [33] (10.1002/ksa.12314)
  • [L3] Grooveplasty patients had less recurrent instability, and similar patient reported outcomes and reoperation rates compared to trochleoplasty. [34] (10.1016/j.arthro.2023.08.056)
  • [L5] Trochleoplasty is a technically demanding technique requiring careful patient selection, detailed knowledge, and surgical skills to avoid severe complications. [35] (10.1007/s00167-022-06954-z)
  • [L5] [41] (10.1016/j.eats.2023.04.030)
  • [L4] The study reports a very low redislocation rate of 1.1% and good clinical outcomes at two-year follow-up after Bereiter trochleoplasty for high grade trochlea dysplasia. [42] (10.1002/ksa.12663)
  • [L4] Deepening trochleoplasty with a thick flap improves clinical and functional outcomes for patients with symptomatic patellar instability with severe trochlear dysplasia. [43] (10.1177/0363546515597679)
  • [L4] Reporting bias is highly prevalent in many abstracts of systematic reviews and meta-analyses on trochleoplasty. [44] (10.1177/03635465251337755)
  • [L4] Trochleoplasty worsens the natural course of patellofemoral arthritis in the long term. [45] (10.1002/ars2.70021)
  • [L5] Excessive or insufficient loading leads to trochlear dysplasia. [46] (10.1186/s13018-023-03500-6)
  • [L3] Trochleoplasty performed using a flexible osteochondral flap is an effective treatment for recurrent patellar instability in patients with severe trochlea dysplasia and gives good results in the medium term. [47] (10.1302/0301-620x.99b3.37884)
  • [L4] Trochlear dysplasia was a significant risk factor for osteoarthritis development, whereas recurrent patellar instability was not. [48] (10.1007/s00167-013-2485-0)
  • [L4] When indicated in the setting of severe trochlear dysplasia, sulcus-deepening trochleoplasty can provide a reliable and successful surgical solution to recurrent patellar instability. [50] (10.1177/2325967117s00389)
  • [L4] Surgical management should be performed in patients in the second and third decades of life practising contact sports and in those patients who present types C and D trochlea dysplasia and patella alta. [51] (10.1007/s00167-022-07273-z)
  • [L3] [52] (10.1007/s00167-011-1410-7)
  • [L3] Modifying the dysplastic trochlea involves approximating the trochlear morphology to the shape of the patella rather than inducing a patella and trochlea mismatch. [53] (10.1302/0301-620x.101b3.bjj-2018-0795.r2)
  • [L4] The tissue in the trochlear groove remained viable after trochleoplasty, with cartilage retaining a distinctive hyaline architecture. [54] (10.1007/s00167-006-0148-0)
  • [L3] Radiographic measures of tracking and alignment changed with knee motion and, in knees with instability symptoms, were most abnormal at lower flexion angles. [88] (10.1016/j.arthro.2014.04.036)
  • [L5] Increased understanding of trochlear morphology and sagittal knee balance as they relate to patella alta will be important for defining the factors that affect patellofemoral stability. [91] (10.1016/j.arthro.2024.03.008)
  • [L4] These findings highlight distinct anatomical phenotypes underlying dynamic patellar maltracking. [92] (10.1177/2325967126s00397)
  • [Paper] The indication should be restricted to patients with unsatisfactory intraoperative patellofemoral tracking after trochleoplasty. [93] (10.1016/j.eats.2023.09.023)
  • [L4] Trochleoplasty with concomitant medial patellofemoral ligament reconstruction is an effective and safe treatment option for patellofemoral instability in the setting of high-grade trochlear dysplasia. [98] (10.1002/ksa.70043)
  • [L4] Recession wedge trochleoplasty is a simple and safe procedure that seems effective to provide patellofemoral stability and pain relief in cases of painful instability with a major dysplastic trochlea or in revision cases when other procedures have failed. [108] (10.1016/j.otsr.2011.07.013)
  • [L4] Sulcus deepening trochleoplasty corrects patellofemoral stability even in patients with severe dysplasia and the long-term functional outcome is better in this group. [109] (10.1016/j.otsr.2015.01.017)
  • [L4] The MPFC fibers demonstrated increased length changes in knees when a greater number of morphological risk factors for patellar instability were present, which worsened in the setting of nonanatomic configurations. [115] (10.1177/03635465231165296)
  • [L4] More severe trochlear dysplasia (types C and D) and femoral tunnel malposition appear to have the most consistent effect on producing higher rates of recurrent dislocation as well as worse PROs. [116] (10.1177/03635465211003342)
  • [L5] The medial patellofemoral ligament is the most important static medial patellar stabilizer, contributing more than 50% to stability, and its meshing with the vastus medialis obliquus dynamizes the ligament during initial flexion. [119] (10.1007/s00167-005-0631-z)
  • [L4] Distally, the length increased at deeper flexion angles, indicating tightening behavior. [124] (10.1177/03635465231205597)
  • [L3] Patients with high-grade trochlear dysplasia show not only abnormal values in common patellofemoral instability risk factors but also a significantly increased sagittal tibial tubercle trochlear-groove distance compared with patients without trochlear dysplasia. [134] (10.1016/j.arthro.2024.05.023)
  • [L4] [136] (10.1016/j.jisako.2025.100387)
  • [L3] The trochlear groove is almost 9mm more anterior to the tibial tuberosity in patients with symptomatic instability, and this distance correlates with measurements of trochlear dysplasia. [137] (10.1177/2325967117s00383)
  • [L2] [141] (10.1097/01.blo.0000203478.27044.9a)
  • [L1] This systematic review showed significant postoperative improvements both in patients undergoing the trochleoplasty procedures and in patients undergoing the nontrochleoplasty procedures for the treatment of patellar instability caused by STD. [142] (10.1016/j.arthro.2014.01.011)
  • [L4] In contrast to general belief, the development of patellofemoral osteoarthritis at 12-year follow-up did not exceed the findings from other trochleoplasty case series. [147] (10.1007/s00167-017-4602-y)

See Also

References

[1] Gettin' in the Groove: Characterizing the Trochleoplasty Learning Curve in Adolescent Patients with Patellofemoral Instability. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/2325967126s00135

[2] CT changes after trochleoplasty for symptomatic trochlear dysplasia. Knee Surgery, Sports Traumatology, Arthroscopy. 2006. DOI: 10.1007/s00167-006-0140-8

[3] Patellofemoral reconstruction for patellar instability with patella alta in middle-aged patients: Clinical outcomes. Orthopaedics & Traumatology: Surgery & Research. 2018. DOI: 10.1016/j.otsr.2018.01.003

[4] Trochlear Morphology and Cartilage Viability After Mini-Open Lateral Approach Trochleaplasty for Patellar Dislocation – 5 Year MRI Follow-Up Study. Journal of ISAKOS. 2023. DOI: 10.1016/j.jisako.2023.03.314

[5] Long-Term Clinical Impact of Radiographic Patellofemoral Osteoarthritis After Sulcus-Deepening Trochleoplasty: A Retrospective Cohort Study. Orthopaedic Journal of Sports Medicine. 2026. DOI: 10.1177/23259671251405283

[6] No growth disturbance after trochleoplasty for recurrent patellar dislocation in adolescents with open growth plates. Orthopaedic Journal of Sports Medicine. 2019. DOI: 10.1177/2325967119s00221

[7] Trochleoplasty provides good clinical outcomes and an acceptable complication profile in both short and long-term follow-up. Knee Surgery, Sports Traumatology, Arthroscopy. 2018. DOI: 10.1007/s00167-018-5311-x

[8] 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. Knee Surgery, Sports Traumatology, Arthroscopy. 2023. DOI: 10.1007/s00167-023-07476-y

[9] Analysis of failed surgery for patellar instability in children with open growth plates. Knee Surgery, Sports Traumatology, Arthroscopy. 2011. DOI: 10.1007/s00167-011-1599-5

[10] No Growth Disturbance After Trochleoplasty for Recurrent Patellar Dislocation in Adolescents With Open Growth Plates. The American Journal of Sports Medicine. 2018. DOI: 10.1177/0363546518794671

[11] Influence of Sulcus-Deepening Trochleoplasty on Patellofemoral Cartilage Integrity in Patients With Severe Trochlear Dysplasia at Short-term to Midterm Follow-up: A Case-Control Study. Orthopaedic Journal of Sports Medicine. 2025. DOI: 10.1177/23259671251326052

[12] Equivalent Outcomes for Patients Following Trochleoplasty as a Primary or Revision Patellar Stabilizing Procedure. Orthopaedic Journal of Sports Medicine. 2017. DOI: 10.1177/2325967117s00388

[13] Trochleoplasty procedures show complication rates similar to other patellar-stabilizing procedures. Knee Surgery, Sports Traumatology, Arthroscopy. 2017. DOI: 10.1007/s00167-017-4766-5

[15] Editorial Commentary: Trochleoplasty: Is It Really That Fearsome and Dangerous a Technique?. Arthroscopy. 2020. DOI: 10.1016/j.arthro.2020.05.050

[16] Isolated Medial Patellofemoral Ligament Reconstruction Results in Lower Failure and Complication Rates Than Isolated Trochleoplasty and Tibial Tubercle Osteotomy: A Systematic Review. Arthroscopy. 2024. DOI: 10.1016/j.arthro.2024.05.019

[17] Current concepts on trochleoplasty procedures for the surgical treatment of trochlear dysplasia. Knee Surgery, Sports Traumatology, Arthroscopy. 2014. DOI: 10.1007/s00167-014-3013-6

[18] Trochlear Shape and Patient-Reported Outcomes After Arthroscopic Deepening Trochleoplasty and Medial Patellofemoral Ligament Reconstruction: A Retrospective Cohort Study Including MRI Assessments of the Trochlear Groove. Orthopaedic Journal of Sports Medicine. 2023. DOI: 10.1177/23259671231171378

[19] Isolated Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Dislocations With Increased Femoral Anteversion and an Absent/Mild J-sign. The American Journal of Sports Medicine. 2026. DOI: 10.1177/03635465261437776

[22] Acceptable outcomes for isolated medial patellofemoral ligament reconstruction despite using higher thresholds for patella alta and regardless the value of tibial tubercle-trochlear groove distance and the degree of trochlear dysplasia—An international multicenter study. Journal of ISAKOS. 2025. DOI: 10.1016/j.jisako.2025.101028

[23] Evaluating the Outcomes of Trochleoplasty in the Treatment of Patellofemoral Instability in the Adolescent and Young Adult Knee With Severe Trochlear Dysplasia: A Minimum 2-Year Follow-up. Orthopaedic Journal of Sports Medicine. 2025. DOI: 10.1177/23259671251321499

[24] Trochleoplasty: Indications in patellar dislocation with high-grade dysplasia. Surgical technique. Orthopaedics & Traumatology: Surgery & Research. 2022. DOI: 10.1016/j.otsr.2021.103160

[25] Patients who undergo tibial tubercle anteromedialization with medial patellofemoral ligament reconstruction demonstrate similar rates of return to sport compared to isolated MPFL reconstruction. Knee Surgery, Sports Traumatology, Arthroscopy. 2024. DOI: 10.1002/ksa.12051

[27] Editorial Commentary : The Entry Point‐Trochlear Groove Angle Measures Lateralization of the Proximal Trochlear Entry Point in Patients With Patellar Instability. Arthroscopy. 2024. DOI: 10.1016/j.arthro.2024.06.005

[29] Clinical outcomes and predictive factors for failure with MPFL reconstruction combined with tibial tubercle osteotomy and lateral retinacular release for recurrent patellar instability. BMC Musculoskeletal Disorders. 2021. DOI: 10.1186/s12891-021-04508-x

[30] The Oswestry-Bristol Classification. The Bone & Joint Journal. 2020. DOI: 10.1302/0301-620x.102b1.bjj-2019-0366.r3

[32] Trochleoplasty as a Solitary Treatment for Recurrent Patellar Dislocation Results in Good Clinical Outcome in Adolescents. The American Journal of Sports Medicine. 2016. DOI: 10.1177/0363546516652894

[33] The role of the most cranial trochlear orientation in patellar maltracking to better characterise trochlear morphology. Knee Surgery, Sports Traumatology, Arthroscopy. 2024. DOI: 10.1002/ksa.12314

[34] Podium Presentation Title: Grooveplasty vs. Trochleoplasty for Trochlear Dysplasia in the Setting of Patellar Instability. Arthroscopy. 2024. DOI: 10.1016/j.arthro.2023.08.056

[35] Good patient satisfaction with low complications rate after trochleoplasty in patellofemoral instability. Knee Surgery, Sports Traumatology, Arthroscopy. 2022. DOI: 10.1007/s00167-022-06954-z

[41] C‐Arm Guidance During Thin Flap Arthroscopic Trochleoplasty for Chronic Patellar Instability. Arthroscopy Techniques. 2023. DOI: 10.1016/j.eats.2023.04.030

[42] Very low dislocation rate and good clinical outcome after Bereiter trochleoplasty and additional procedures following the Copenhagen patella–femoral instability algorithm: One‐ and two‐years outcomes from a consecutive cohort of 368 cases. Knee Surgery, Sports Traumatology, Arthroscopy. 2025. DOI: 10.1002/ksa.12663

[43] Deepening Trochleoplasty With a Thick Osteochondral Flap for Patellar Instability. The American Journal of Sports Medicine. 2015. DOI: 10.1177/0363546515597679

[44] Reporting Bias Prevalence in Systematic Reviews and Meta-analyses on Trochleoplasty: A Systematic Review. The American Journal of Sports Medicine. 2025. DOI: 10.1177/03635465251337755

[45] Trochleoplasty Is Associated With High Rates of Patellofemoral Arthritis: A Systematic Review. Arthroscopy, Sports Medicine, and Rehabilitation. 2026. DOI: 10.1002/ars2.70021

[46] Abnormal patellar loading may lead to femoral trochlear dysplasia: an experimental study of patellar hypermobility and patellar dislocation in growing rats. Journal of Orthopaedic Surgery and Research. 2023. DOI: 10.1186/s13018-023-03500-6

[47] Trochleoplasty with a flexible osteochondral flap. The Bone & Joint Journal. 2017. DOI: 10.1302/0301-620x.99b3.37884

[48] Patellofemoral osteoarthritis after Insall's proximal realignment for recurrent patellar dislocation. Knee Surgery, Sports Traumatology, Arthroscopy. 2013. DOI: 10.1007/s00167-013-2485-0

[50] Trochleoplasty is a Viable Option for Patellar Instability in Patients with Severe Trochlear Dysplasia: Early Outcomes Analysis of the U.S. Experience. Orthopaedic Journal of Sports Medicine. 2017. DOI: 10.1177/2325967117s00389

[51] Management of the first episode of traumatic patellar dislocation: an international survey. Knee Surgery, Sports Traumatology, Arthroscopy. 2022. DOI: 10.1007/s00167-022-07273-z

[52] Classification of trochlear dysplasia as predictor of clinical outcome after trochleoplasty. Knee Surgery, Sports Traumatology, Arthroscopy. 2011. DOI: 10.1007/s00167-011-1410-7

[53] Deepening trochleoplasty and medial patellofemoral ligament reconstruction normalize patellotrochlear congruence in severe trochlear dysplasia. The Bone & Joint Journal. 2019. DOI: 10.1302/0301-620x.101b3.bjj-2018-0795.r2

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