Distal Realignment Procedures Research Articles

Modified Grammont Soft-Tissue Distal Patellar Realignment and Medial Patellofemoral Ligament Reconstruction for Patellofemoral Instability in Pediatric Patients

Patellar dislocation is a relatively common pediatric injury, which often results in recurrent patellofemoral instability. An increased tibial tubercle–trochlear groove distance predisposes to patellofemoral instability and can be corrected with a distal realignment procedure. Soft-tissue distal realignment procedures must be used in the pediatric population to avoid the risks of premature physeal closure associated with tibial tubercle osteotomies. Several soft-tissue distal realignment procedures have been described, with no consensus as to the optimal technique. When combined with medial patellofemoral ligament reconstruction, distal realignment procedures can restore patellofemoral stability through the entire flexion arc. This article describes a modification of the Grammont distal patellar realignment procedure in conjunction with medial patellofemoral ligament reconstruction for the management of pediatric patellofemoral instability.

Bioabsorbable magnesium screw fixation for tibial tubercle osteotomy; a preliminary study.

Background and aim:Metallic screws are commonly used to fix tibial tubercle osteotomies (TTO). However, hardware removal late after osteotomy union is one of the most common causes of reoperation following TTOs. The use of bioabsorbable screws may eliminate secondary surgeries, but there is no study on their use in this indication. The purpose of this retrospective study was to evaluate the safety and efficacy of bioabsorbable magnesium (Alloy: MgYREZr) screws in tibial tubercle osteotomy (TTO) fixation.Methods:Ten consecutive patients with objective patellar instability who underwent distal realignment procedure using Fulkerson TTO were retrospectively reviewed. The osteotomy was secured with two parallel 4.8 mm magnesium screws in all patients. Kujala score and Lysholm knee score were used to assess the functional outcomes before and after the operation. During the follow-up, the union of the osteotomy, displacement, and other imaging findings were evaluated with serial knee radiographs.Results:There were five male and five female patients with a mean age of 23.4±9.2 years (range, 15–45). The mean follow-up duration was 11.5±3.2 months (range,6–17 months). The osteotomy united in all cases at an average of 3 months. No infection or wound healing problems were seen. A significant increase in Kujala (p:.005) and Lysholm knee scores (p:.005) were recorded in all patients.Conclusion:Despite a limited number of patients were reviewed, the findings support that bioabsorbable magnesium screws can be safely used as an alternative fixation technique in TTO. Furthermore, it provides the advantage of eliminating the need for implant removal. (www.actabiomedica.it)

Anteriorization of the Tibial Tubercle With Osteotomy, Combined With Cartilage Restoration in the Patellofemoral Joint: A Surgical Technique

Left untreated, cartilage defects of the knee are responsible for substantial patient morbidity and may lead to osteoarthritis. This has led to the development of several techniques to improve healing potential, including microfracture, osteochondral autograft, osteochondral allografts, autologous chondrocyte implantation, and matrix-assisted autologous chondrocyte implantation. Of paramount importance when addressing patellofemoral (PF) cartilage defects is treating associated PF malalignment. We describe a surgical technique for tibial tubercle anteriorization in conjunction with autologous chondrocyte implantation for the treatment of PF cartilage lesions. In our opinion, a distal realignment procedure should be routinely performed for any cartilage restoration procedure of the PF joint as it may delay the onset of osteoarthritis.

Distal alignment procedures for patellofemoral instability: comprehensive review of the literature.

Patellofemoral disorders are a common cause of complaint in adolescent patients. Several distal realignment procedures performed in isolation or combination with proximal alignment have been described. To clarify the role of distal alignment for patellofemoral instability, a systematic review of the literature was conducted. Two independent reviewers accessed the following databases: PubMed, Medline, CINAHL, Cochrane, EMBASE and Google Scholar. A total of 1478 patients with a mean age of 22.78years were included. The mean follow-up was 86.53 months. The average Kujala score improved from 57.66 to 82.73. The average Lysholm score improved from 63.25 to 87.87, and the average Tegner score from 3 to 4.16. VAS score improved from an average 8 to 2.56. We account a total of 46 major complications, 45 minor complications and 95 recurrences. The risk of a recurrence is 6.42%. A total of 122 additional surgeries were performed during the follow-up. This systematic review of literature suggests the importance to identify the pathological background that predisposes patients for developing patellofemoral instability and its implications for the decision-making process. The optimal treatment for patellofemoral instability should be individualized to address the specific anatomical abnormalities that contribute to patellofemoral dislocations. Distal alignments are a feasible solution to restore correct patellar biomechanics and tracking, leading to an improvement of patients' quality of life.

The Outcomes of Isolated Distal Realignment Procedures in Patellofemoral Instability: A Systematic Review and Meta-analysis.

Distal realignment procedures are now commonly performed routinely with proximal realignment procedures. Despite so, only a limited number of publications exist that have looked into the efficacy of isolated distal realignment procedures, and whether there is indeed a need for routine proximal realignment procedures to be added to the distal realignment procedures. The current systematic review and meta-analysis aims to evaluate the outcomes of isolated distal realignment procedures in the management of patellofemoral instability. The review was conducted using the preferred reporting items for systematic reviews and meta-analyses (PRSIMA) guidelines. All studies that reported the outcomes of isolated distal realignment procedures for patellofemoral instability were included. A total of six publications were included, with 347 knees. All studies consistently reported a decrease in the rates of patellofemoral instability or maltracking (odds ratio [OR]: < 0.01; 95% confidence interval [CI]: < 0.01-0.01) and an increase in the odds of having a good outcome (OR: 0.01; 95% CI: < 0.01-0.02) after distal realignment procedures. A total of 24 out of 306 patients (7.8%) had postoperative instability or maltracking, and a total of 220 out of 303 patients (72.6%) were rated to have good or excellent outcomes postoperatively. Isolated distal realignment procedures can lead to good outcomes when used in the management of patellofemoral instability. These include a significantly decreased rate of patellofemoral instability or maltracking and a significantly increased number of patients with excellent or good outcomes postoperatively. Comparisons between patients with and without additional proximal realignment procedures suggest that additional proximal realignment procedures do not definitely improve the outcomes of distal realignment procedures and, therefore, should not be routinely performed in all patients undergoing distal realignment procedures. The Level of Evidence for this study is IV.

Clinical Outcomes of Isolated Medial Patellofemoral Ligament Reconstruction in Patients with Patella Alta and Excessive Rotational Malalignment

In patients with recurrent lateral patellar instability(LPI), it remains unclear when adjunctive distal realignment procedures are warranted to diminish chances of secondary instability. The objective of this study was to evaluate the surgical outcomes after isolated medial patellofemoral ligament (MPFL) reconstruction and identify risk factors for adverse patient endpoints.

The Outcomes of Isolated Distal Realignment Procedures in Patellofemoral Instability - A Systematic Review and Meta-Analysis

The Outcomes of Isolated Distal Realignment Procedures in Patellofemoral Instability - A Systematic Review and Meta-Analysis

Patellar Instability in the Skeletally Immature.

This review will focus on the evaluation and management of patellar instability in the developing patient. A large number of surgical techniques have been described to prevent recurrent patellofemoral instability in the pediatric population, including both proximal and distal realignment procedures. The wide variety of treatment options highlights the lack of agreement as to the best surgical approach. However, when a comprehensive exam and workup are paired with a surgical plan to address each of the identified abnormalities, outcomes are predictably good. Patellar instability is a common knee disorder in the skeletally immature patient that presents a unique set of challenges. Rates of re-dislocation in pediatric and adolescent patients are higher than in their adult counterparts. Careful consideration of the physeal and apophyseal anatomy is essential in these patients. While the majority of primary patellar instability events can be treated conservatively, multiple events often require surgical intervention.

Arthroscopic assessment of patellofemoral tracking predicts patellar instability

Objectives:Surgical management of patellar instability includes proximal realignment procedure such as MPFL reconstruction. The decision to add a distal realignment procedure of tibial tubercle transfer is based on severity of patellar instability judged on either TTTG distance or arthroscopic patellofemoral tracking. We set out to validate our use of arthroscopic patellofemoral tracking for patellar instability management algorithm by analyzing its reproducibility and whether it correlates with patellar instability.Methods:A prospective observational study was carried out at Perth Orthopaedic and Sports Medicine Centre. Patient clinical presentations were divided into three groups - patellofemoral instability, patellofemoral pain, and no patellofemoral symptoms. Standard technique included low flow arthroscopy with single anterolateral viewing portal. Height of the fluid bag and presence of a knee holder was recorded. Knee flexion angle where patella first centrally engages in the trochlear groove was defined as Patellofemoral Congruent Angle (PCA). PCA was estimated by the primary surgeon and the angle was confirmed using a sterile goniometer. A second surgeon, blinded to the initial assessment, then repeated the measurements. Surgeon estimation error, interobserver reliability, and correlation with clinical presentation was analysed.Results:57 knees were assessed for interobserver reliability. Intra-class correlation was 0.994 between surgeon’s estimate and goniometer reading. Intra-class correlation was 0.992 between the two surgeon’s readings suggesting a very high correlation. 157 patients had their PCA recorded and compared with their diagnosis. Mean PCA was 40 degrees in normal patients, and 118 degrees in patellar instability (p-value <0.001).Conclusion:Arthroscopic assessment of patellofemoral tracking is reproducible and correlates with patellar instability. A cut-off value of 40 degrees is recommended to differentiate normal tracking from abnormal.

Arthroscopic assessment of patellofemoral tracking predicts patellar instability

Objectives:Surgical management of patellar instability includes proximal realignment procedure such as MPFL reconstruction. The decision to add a distal realignment procedure of tibial tubercle transfer is based on severity of patellar instability judged on either TTTG distance or arthroscopic patellofemoral tracking. We set out to validate our use of arthroscopic patellofemoral tracking for patellar instability management algorithm by analyzing its reproducibility and whether it correlates with patellar instability.Methods:A prospective observational study was carried out at Perth Orthopaedic and Sports Medicine Centre. Patient clinical presentations were divided into three groups - patellofemoral instability, patellofemoral pain, and no patellofemoral symptoms. Standard technique included low flow arthroscopy with single anterolateral viewing portal. Height of the fluid bag and presence of a knee holder was recorded. Knee flexion angle where patella first centrally engages in the trochlear groove was defined as Patellofemoral Congruent Angle (PCA). PCA was estimated by the primary surgeon and the angle was confirmed using a sterile goniometer. A second surgeon, blinded to the initial assessment, then repeated the measurements. Surgeon estimation error, interobserver reliability, and correlation with clinical presentation was analysed.Results:57 knees were assessed for interobserver reliability. Intra-class correlation was 0.994 between surgeon’s estimate and goniometer reading. Intra-class correlation was 0.992 between the two surgeon’s readings suggesting a very high correlation. 157 patients had their PCA recorded and compared with their diagnosis. Mean PCA was 40 degrees in normal patients, and 118 degrees in patellar instability (p-value <0.001).Conclusion:Arthroscopic assessment of patellofemoral tracking is reproducible and correlates with patellar instability. A cut-off value of 40 degrees is recommended to differentiate normal tracking from abnormal.

An Algorithmic Approach to the Management of Recurrent Lateral Patellar Dislocation.

High-level evidence supports nonoperative treatment for first-time lateral acute patellar dislocations. Surgical intervention is often indicated for recurrent dislocations. Recurrent instability is often multifactorial and can be the result of a combination of coronal limb malalignment, patella alta, malrotation secondary to internal femoral or external tibial torsion, a dysplastic trochlea, or disrupted and weakened medial soft tissue, including the medial patellofemoral ligament (MPFL) and the vastus medialis obliquus. MPFL reconstruction requires precise graft placement for restoration of anatomy and minimal graft tension. MPFL reconstruction is safe to perform in skeletally immature patients and in revision surgical settings. Distal realignment procedures should be implemented in recurrent instability associated with patella alta, increased tibial tubercle-trochlear groove distances, and lateral and distal patellar chondrosis. Groove-deepening trochleoplasty for Dejour type-B and type-D dysplasia or a lateral elevation or proximal recession trochleoplasty for Dejour type-C dysplasia may be a component of the treatment algorithm; however, clinical outcome data are lacking. In addition, trochleoplasty is technically challenging and has a risk of substantial complications.

Radiographic and Anatomic Evaluation of Tibial Tubercle to Trochlear Groove Distance.

Background A lateralized tibial tubercle is an important anatomic predictor of patellar instability and can be used as an indication for a distal realignment procedure. Currently, tibial tubercle to trochlear groove (TT-TG) distance is measured on computed tomography (CT); however, radiographs could be a safer and more efficient modality. The aim of this study is to evaluate and compare TT-TG measurements obtained using CT, anatomical dissections, and a novel radiographic technique. Furthermore, we evaluated the effects of knee flexion and tibial rotation on these measurements. Methods TT-TG distances were measured on 11 fresh cadaver specimens with CT and compared with anatomic measurements obtained from dissection in full knee extension and 90-degree flexion. Both imaging- and dissection-derived measurements were obtained in neutral, external, and internal tibial rotation. The TT-TG distance was also measured on a modified sunrise X-ray view (knee at 90 degrees). Results The TT-TG distance obtained on CT was 13.00 ± 1.05 mm and was comparable to measurements derived from anatomic dissections in extension (14.88 ± 1.10 mm) and 90 degrees (12.40 ± 1.93 mm) (p ≥ 0.05). The X-ray measurements of TT-TG distance (5.62 ± 1.16 mm) were significantly different than those measured on CT (p ≤ 0.05). TT-TG distances in neutral tibial position measured on CT and dissection were significantly different than distances measured in full external (19.79 ± 1.33 and 20.92 ± 1.15 mm, respectively) and internal tibia rotation (6.45 ± 1.00 and 10.33 ± 1.19 mm, respectively) (p ≤ 0.05). Conclusions TT-TG distance measured on CT is comparable to measurements from dissections in both full extension and 90-degree flexion. Tibial rotation has a significant effect on TT-TG measurements. Radiographic measurements did not correlate with CT and anatomic measurements. Clinical Relevance CT-derived TT-TG measurements are accurate throughout knee range of motion; however, it is important to maintain neutral lower leg rotation to not generate a false-positive or false-negative measurement. Radiographic measurement of TT-TG ration is not currently recommended.

Patellar instability in children and adolescents

Patellar instability is a common occurrence in the skeletally immature patient population, and multiple treatment options exist. Nonoperative treatment is appropriate for patients without osteochondral injuries and includes bracing and physical therapy focusing on strengthening of the gluteals as well as the vastus medialis obliquus muscles. Risk factors for recurrent instability include patella alta, trochlear dysplasia, and age younger than 25 yr. Isolated reconstruction of the medial patellofemoral ligament is indicated in patients with recurrent instability with normal tibial tubercle-trochlear groove distances with or without trochlear dysplasia. Distal realignment procedures risk physeal injury and are thus not routinely used in the skeletally immature population. Long-term data on the effect that trochleoplasty has on chondral surface have not been established and it has thus been a procedure reserved primarily for skeletally mature patient populations with chronic patellar instability. Despite multiple operative treatment methods, knee pain, decreased knee flexion, and recurrent instability are the most common postoperative complications.

Arthroscopic proximal realignment for recurrent patellar instability

Introduction Patellar instability is a common cause of knee pain and disability. It can be managed with conservative treatment. Patients in whom conservative treatment fails, usually some form of surgical realignment procedure is performed. Treatment of recurrent patellar instability is a source of much controversy. The operative procedures commonly used include lateral retinaculum release, proximal realignment, distal realignment, or combined procedures. The aim of this study was to evaluate the results of all-inside arthroscopic proximal realignment for recurrent patellar instability. Patients and methods Twenty-six patients (16 female and 10 male patients) undergoing proximal realignment procedure were treated with all-arthroscopic lateral release and medial plication. The patients were operated on under general anesthesia and tourniquet control. Postoperatively, a brace was locked in full extension for 1 week, followed by physical therapy for 2 months. All patients were assessed 6 months postoperatively on the basis of the Lysholm knee scoring scale. Results The mean follow-up period was 37 months (range, 29-48 months). The mean Lysholm knee scoring scale improved significantly from a mean of 55.4 points preoperatively to a mean of 91.2 points postoperatively. There was good improvement as regards pain, stability, ability to climb stairs, and confidence in the operated knees. Conclusion Arthroscopic proximal realignment for recurrent patellar instability is a minimally invasive procedure with minimal complications. It is associated with less morbidity. The period of rehabilitation is relatively shorter, and the results are comparable to those of the established open surgical techniques for this condition.

Medial patellofemoral ligament (MPFL) reconstruction improves radiographic measures of patella alta in children.

Patellofemoral instability has previously been associated with patella alta. The purpose of this study was to evaluate adolescents undergoing MPFL reconstruction for standardized indices of patellar height on pre- and post-operative radiographs to determine if these radiographic parameters change after MPFL reconstruction. Twenty-seven children (mean age 14.9years old) who underwent MPFL reconstruction without a distal realignment procedure were evaluated pre- and post-operatively for Insall-Salvati Ratio, Modified Insall-Salvati Ratio, and Caton-Deschamps Index by three blinded raters. Intrarater reliability and interrater reliability were calculated for each index, and means of each were compared pre- and post-operatively to determine if MPFL reconstruction was associated with improved patellar height. All three indices of patellar height indicated that there was patella alta present in this cohort preoperatively. Furthermore, all three measures were significantly improved postoperatively (paired t-tests, P<0.001 for all) to within normal childhood ranges. Interrater reliability was excellent for both the Insall-Salvati Ratio (ICC=0.89) and Caton-Deschamps Index (ICC=0.78), and adequate for the Modified Insall-Salvati Ratio (ICC=0.57); intrarater reliability was excellent for all three (ICCs: 0.91, 0.82, 0.80 respectively). MPFL reconstruction in children using hamstring autograft was associated with consistently improved patellar height indices to within normal childhood ranges. This associated improvement of patellar height as measured on a lateral radiograph may subsequently improve patellofemoral mechanics by drawing the patella deeper and more medially into the trochlear groove. Level 4.

Measurement of tibial tuberosity-trochlear groove distance: evaluation of inter- and intraobserver correlation dependent on the severity of trochlear dysplasia.

Excessive tibial tuberosity-trochlear groove distance (TT-TG) is considered as one of the major risk factors in patellofemoral instability (PFI). TT-TG characterises the lateralisation of the tibial tuberosity and the medialisation of the trochlear groove in the case of trochlear dysplasia. The aim of this study was to assess the inter- and intraobserver reliability of the measurement of TT-TG dependent on the grade of trochlear dysplasia. Magnetic resonance imaging (MRI) scans of 99 consecutive knee joints were analysed retrospectively. Hereof, 61 knee joints presented with a history of PFI and 38 had no symptoms of PFI. After synopsis of the axial MRI scans with true lateral radiographs of the knee, the 61 knees presenting with PFI were assessed in terms of trochlear dysplasia. The knees were distributed according to the four-type classification system described by Dejour. Regarding interobserver correlation for the measurements of TT-TG in trochlear dysplasia, we found r=0.89 (type A), r=0.90 (type B), r=0.74 (type C) and 0.62 (type D) for Pearson's correlation coefficient. Regarding intraobserver correlation, we calculated r=0.89 (type A), r=0.91 (type B), r=0.77 (type C) and r=0.71 (type D), respectively. Pearson's correlation coefficient for the measurement of TT-TG in normal knees resulted in r=0.87 for interobserver correlation and r=0.90 for intraobserver correlation. Decreasing inter- and intraobserver correlation for the measurement of TT-TG with increasing severity of trochlear dysplasia was detected. In our opinion, the measurement of TT-TG is of significance in low-grade trochlear dysplasia. The final decision to perform a distal realignment procedure based on a pathological TT-TG in the presence of high-grade trochlear dysplasia should be reassessed properly. Retrospective study, Level II.

Clinical and Electromyographic Results of Proximal and Distal Realignment Procedures in Young Patients With Recurrent Patellar Dislocations

Background: Until now, no study has been published about the electromyographic changes in the extensor apparatus after the Green procedure for proximal realignment in young patients with recurrent patellar dislocations. This electromyographic study was performed to analyze imbalances between the vastus medialis and vastus lateralis muscles after different patellar realignment procedures. Hypothesis: Surgical proximal realignment leads to electromyographic changes in the extensor apparatus of the knee and to imbalances between the vastus medialis and vastus lateralis muscles. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 28 knees of 25 patients, with a mean age of 15 years, were treated operatively for recurrent patellar dislocations. The mean follow-up was 6.3 years. Depending on the type of surgical intervention, the patients were assigned to 3 different groups: the patients of group 1 underwent only the Green vastus medialis obliquus (VMO) advancement, group 2 was treated with a combination of the Green proximal and the Roux-Goldthwait distal realignment, and group 3 was treated with a combination of the Green proximal realignment and an additional tubercle transfer. All patients underwent clinical, radiological, and electromyographic examinations. The muscle activities of a healthy control group without patellar dislocations were used for comparison. Results: A combination of the Green procedure and tubercle transfer led to significantly better clinical results and a lower number of redislocations (P < .05) compared with patients who underwent only the Green proximal realignment. While ascending or descending stairs, the ratio between the electromyographic activities of the vastus medialis and vastus lateralis muscles in groups 1 and 2 was significantly smaller compared with the control group (P < .02). Only the electromyograms of group 3 revealed a balanced extensor apparatus during loading with comparable activities of the vastus medialis and vastus lateralis muscles and no significant difference to the control group (P = .37). Conclusion: Our electromyographic investigations showed the importance of the vastus medialis in the pathogenesis of malalignment of the extensor mechanism. The Green VMO advancement without tibial tubercle transfer is not able to balance the activities of the vastus medialis and vastus lateralis muscles and cannot be recommended for further use.

Patellar Dislocation With Genu Valgum Treated by DFO

Congenital habitual patellar dislocation is a rare condition of the knee where the patella dislocates during flexion and relocates during extension. The congenital form is permanent, irreducible, and presents at birth. It is characterized by a short quadriceps and a major patellofemoral dysplasia and short height. This article presents a rare case of a 27-year-old woman with recurring bilateral habitual dislocation of the patella after a failed previous proximal and distal realignment procedure. Clinical examinations of both knees revealed genu valgus knees and lateral joint pain that recurred after several previous operations. Radiographs of both knees showed patellar dislocation and genu valgum associated with patellofemoral dysplasia and osteoarthritis of the lateral compartment. Long-leg standing radiographs showed an anatomic tibiofemoral angle of right 13° and left 6° valgus and a mechanical tibiofemoral angle of right 8° and left 2° valgus and weight-bearing line of 65% on the right and 48% on the left. The authors performed a distal femoral closing wedging osteotomy to correct the valgus deformity, and then percutaneous lateral release and medial reefing were performed to stabilize the patellas of both knees simultaneously.

Complications of Medial Patellofemoral Ligament Reconstruction: Common Technical Errors and Factors for Success

The role of medial patellofemoral ligament reconstruction in reestablishing patellofemoral joint stability has recently been reported with increasing frequency. The purpose of this study was to review the reported complications of medial patellofemoral ligament reconstruction, highlight the common technical errors, and discuss the potential complications that can arise from this procedure. We review the literature on medial patellofemoral ligament reconstruction, including the reported causes of failure. In addition, we present three cases and discuss the multiple factors that are crucial for success, including patient selection, tunnel placement, graft isometry, and determination of the need for concurrent realignment surgery. The principles of surgical management require a thorough understanding of proper patient selection and of the interaction between the roles of the osseous and soft-tissue restraints on the patella. Creating a logical treatment algorithm based on pathoanatomy can elucidate the need for concurrent distal realignment procedures. Tunnel positioning is critical in recreating appropriate patellofemoral alignment. The reported complications include patellofemoral arthrosis, graft impingement, and graft failure. Many of the complications that can arise from medial patellofemoral ligament reconstruction are the result of technical error and can be avoided by understanding the potential complications associated with this procedure.

Chronische patellofemorale Instabilität

Chronic patellofemoral instability may lead to pain and early osteoarthrosis. Recurrent dislocations of the patella, lateral subluxation and chronic dislocation are summarized under this generic term. There are five different factors which may be responsible of the development of chronic patellofemoral instability: 1) elongation of the medial patellofemoral ligament (MPFL), 2) patella alta, 3) increased distance between tibial tuberosity and trochlea groove (TTTG) distance, 4) trochlea dysplasia and 5) torsional malalignment. To rule out these factors clinical examination, radiological diagnostics (luxation, subluxation in the Defilée view, trochlea morphology, patella alta) and magnetic resonance imaging (MRI) of TTTG distance and trochlea morphology are crucial. The indications of operative treatment are chronic pain with subluxation, chronic dislocation and recurrent dislocation. Currently the former frequently and universally used lateral release is only indicated in cases of subluxation and positive tilt. Biomechanical studies have shown that a lateral release will otherwise increase patellofemoral instability. The choice of the surgical technique depends on the factors underlying patellofemoral instability, the conditions of growth plate and cartilage damage. Among the different surgical options proximal and distal realignment procedures are differentiated. In cases of MPFL elongation and mild passive instability a medial reefing might be successful. In cases of MPFL elongation, high passive instability up to 30° of flexion (with or without trochlear dysplasia) MPFL reconstruction may be the treatment of choice. A trochleoplasty is rarely indicated. This treatment may be considered in cases of high grade trochlea dysplasia and passive instability at more than 30° of flexion. If the TTTG distance is increased (>20 mm) or in cases of patella alta distal realignment with tibial tubercle transfer should be considered. This operation might also be useful in the presence of lateral cartilage damage as an anteromedialization of the patella.