Patellar dislocation with genu valgum treated by DFO

Additional Plate Fixation of Hinge Fractures After Varisation Distal Femoral Osteotomies Provides Favorable Torsional Stability: A Biomechanical Study

BACKGROUND

Hinge fractures are considered risk factors for delayed or nonunion of the osteotomy gap in distal femoral osteotomies (DFOs). Limited evidence exists regarding the treatment of hinge fractures after DFO, which could improve stability and thus bone healing.

PURPOSE

To (1) examine the effect of hinge fractures on the biomechanical properties of the bone-implant construct, (2) evaluate the biomechanical advantages of an additional fixation of a hinge fracture, and (3) test the biomechanical properties of different types of varisation DFOs.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 32 fresh-frozen human distal femora equally underwent medial closing wedge DFO or lateral opening wedge DFO using a unilateral locking compression plate. The following conditions were serially tested: (1) preserved hinge; (2) hinge fracture along the osteotomy plane; (3) screw fixation of the hinge fracture; and (4) locking T-plate fixation of the hinge fracture. Using a servo-hydraulic materials testing machine, we subjected each construct to 15 cycles of axial compression (400 N; 20 N/s) and internal and external rotational loads (10 N·m; 0.5 N·m/s) to evaluate the stiffness. The axial and torsional hinge displacement was recorded using a 3-dimensional optical measuring system. Repeated-measures 1-way analysis of variance and post hoc Bonferroni correction were used for multiple comparisons. Statistical significance was set at P < .05.

RESULTS

Independent from the type of osteotomy, a fractured hinge significantly (P < .001) increased rotational displacement and reduced stiffness of the bone-implant construct, resulting in ≥1.92 mm increased displacement and ≥70% reduced stiffness in each rotational direction, while the axial stiffness remained unchanged. For both procedures, neither a screw nor a plate could restore intact rotational stiffness (P < .01), while only the plate was able to restore intact rotational displacement. However, the plate always performed better compared with the screw, with significantly higher and lower values for stiffness (+38% to +53%; P < .05) and displacement (-55% to -72%; P < .01), respectively, in ≥1 rotational direction. At the same time, the type of osteotomy did not significantly affect axial and torsional stability.

CONCLUSION

Hinge fractures after medial closing wedge DFO and lateral opening wedge DFO caused decreased bone-implant construct rotational stiffness and increased fracture-site displacement. In contrast, the axial stiffness remained unchanged in the cadaveric model.

CLINICAL RELEVANCE

When considering an osteosynthesis of a hinge fracture in a DFO, an additional plate fixation was the construct with the highest stiffness and least displacement, which could restore intact hinge rotational displacement.

Patient-Specific Instrumentation for Medial Closing Wedge Distal Femoral Osteotomy With Patellar Osteochondral Allograft

The primary indications for performing a medial closing wedge distal femoral osteotomy are valgus knee malalignment, lateral knee compartment overload, lateral meniscus insufficiency, and/or lateral compartment osteoarthritis or cartilage damage. Without correction of this malalignment, there is an increased risk for chondral damage in the lateral and patellofemoral compartment of the knee. The optimal candidates for this procedure are young, active individuals with moderate to severe arthritis in the lateral compartment. Recently, preoperative planning for high tibial and distal femoral osteotomies (HTOs and DFOs) using 3-dimensional (3D) patient-specific instrumentation (PSI) has increased in popularity. Successful patient outcomes have been reported using this technique. This Technical Note illustrates our preferred technique that uses 3D PSI in addition to a patellar OCA transplant when treating a symptomatic cartilage lesion associated with genu valgum.

Distal femur varus-producing osteotomy: An updated review of patellofemoral implications and clinical outcomes

Background: Recent evidence seems to suggest the effectiveness of distal femur varus osteotomy in the management of patellofemoral instability in the setting of genu valgum. However, literature on this subject remains scarce and consists mostly of small case series. Hypothesis: This study aims to systematically review the literature on varus-producing distal femur osteotomy and critically analyze its implications on patellofemoral kinematics and stability. Results: The statistical analysis revealed that this surgery is able to restore a mechanical angle (mean hip–knee–ankle (HKA): 0.22°) and to improve the main clinical outcomes (Kujala score, Knee injury and Osteoarthritis Outcome Score, visual analog scale) after a mean follow up of 2.5 years. An objective of the present review was to investigate the mechanical implications of femoral osteotomy on the patellofemoral biomechanics. Indeed, the statistical analysis demonstrated changes after surgery in the main patella-femoral radiological angles (modified Insall–Salvati index, Caton–Deschamps index, Blackburne–Peel index). Interestingly the overcorrection of the mechanical axis (HKA), resulting in varus, had similar outcomes compared to studies that obtained a mechanical axis. Level of Evidence: Level II study.

Genu Valgum Correction and Biplanar Osteotomies

Valgus malalignment is an important risk factor in recurrent patella instability. This article explores the role of corrective osteotomy and discusses the various described methods both on the femoral and tibial sides of the joint. A detailed operative technique of medial closing wedge distal femoral osteotomy is included.

Management of Chondral Defects Associated with Patella Instability

Cartilage defects of the patellofemoral joint are commonly found in association with patellar instability owing to abnormal biomechanics. Strategies to address chondral defects of the patellofemoral joint secondary to instability should first address causes of recurrent instability. Most patellofemoral chondral defects associated with instability are less than 2 cm2 and do not generally require intervention beyond chondroplasty. Larger defects of the patella and/or the trochlea can be repaired with osteochondral or surface cartilage repair.

Detection of Lateral Hinge Fractures After Medial Closing Wedge Distal Femoral Osteotomy: Computed Tomography Versus Plain Radiography

BACKGROUND

Limited evidence exists in the literature regarding the detection rates of lateral hinge fracture (LHF) on computed tomography (CT) after medial closing wedge distal femoral osteotomy (MCDFO). Moreover, the effect of LHF on bone healing after MCDFO remains unclear.

HYPOTHESIS

The detection rates of LHF after MCDFO would be higher on CT than on plain radiography. The incidence of problematic bone healing would be higher in the knees with LHF than in those without LHF.

STUDY DESIGN

Cohort study (diagnosis), Level of evidence, 3.

METHODS

Patients who underwent MCDFO between May 2009 and July 2019 were retrospectively evaluated. The presence of LHF was evaluated using immediate postoperative plain radiography and CT. The detection rates of LHF on plain radiography and CT were compared. The incidence of problematic bone healing (nonunion, delayed union, and loss of correction) was also compared between the knees with LHF and those without LHF.

RESULTS

A total of 55 knees of 43 patients (mean age, 37.7 ± 16.7 years) were included in the study. Although 33 LHFs were detected on CT, only 19 LHFs were detected on plain radiography. The detection rate of LHF was significantly higher on CT than on plain radiography (60% vs 34.5%; P = .008). At 1-year follow-up, 10 cases of problematic bone healing (1 nonunion, 4 delayed unions, and 5 losses of correction) were identified. The incidence of problematic bone healing was significantly higher in the knees with LHF than in those without LHF as shown on plain radiography (36.8% vs 8.3%; P = .001) and CT (30.3% vs 0%; P = .004).

CONCLUSION

LHF can be detected better on CT than on plain radiography and has a negative effect on bone healing after MCDFO. For patients with LHF detected on either plain radiography or CT, careful rehabilitation with close follow-up is recommended.

Surgical Technique for Obligate Flexion Patellar Dislocation: Medial Patellofemoral Ligament Reconstruction, Distal Femoral Osteotomy, Quadricepsplasty, and Lateral Retinacular Reconstruction with Dermal Allograft

Lateral patellar dislocation is a relatively common pathology that can be surgically treated with a medial patellofemoral ligament reconstruction. In rare occurrences patients can present with patellar maltracking that results in obligate patellar instability in flexion but central tracking in extension. This presentation can be much more complicated to treat surgically and may require a combination of multiple patellofemoral procedures. In this technique we describe a four-pronged treatment approach for improving patellar tracking in a patient with obligate flexion patellar dislocation and valgus malalignment including VY quadricepsplasty, distal femoral osteotomy, medial patellofemoral ligament reconstruction, and lateral retinacular and capsular reconstruction with a dermal allograft.

Linear influence of distal femur osteotomy on the Q-angle: one degree of varization alters the Q-angle by one degree

PURPOSE

The effect of a distal femur varization osteotomy on patellofemoral biomechanics in genu valgum is unknown. The purpose of this study was to quantify the influence of frontal leg axis correction on the Q-angle with a novel three-dimensional (3-D) measurement method.

METHODS

3-D surface models of ten lower extremities were generated using patient computed tomography (CT) data. The preoperative 3-D Q-angle was measured using a novel defined and validated 3-D measurement method. Biplanar supracondylar osteotomies were simulated with different degrees of varus correction (from 1° to 15°) in one-degree steps beginning from the preoperative valgus deformity, resulting in a total of 150 simulations. Additionally, mechanical leg axis and 3-D Q-angle measurements were performed on 3-D surface models of the postoperative CT scans of the same individuals. Further, pre- and postoperative TT-TG distance was measured.

RESULTS

Mean preoperative Q-angle was 15.8 ± 3.9° (range 10°-21.4°) with a mean preoperative mechanical leg axis of 6.5° ± 2.4 valgus (range 3.8°-11.6° valgus). The Q-angle changed linearly 0.9 ± 0° per 1° of varization. No difference was detected between simulated 3-D Q-angles and effectively corrected postoperative values (n.s.). TT-TG distance changed irregularly and minimally, and with no correlation to the degree of varization.

CONCLUSION

Distal femur varization osteotomy has a linear effect on the Q-angle with a change of 1° per 1° of varization. The difference in TT-TG distance was mainly due to an unintentional rotational component implemented during surgery.

[Patellar dislocation : Causes and treatment]

The causes of patellofemoral instability (PFI) are complex. In accordance with the current literature a classification was developed which clearly weights all entities and derives diagnostic and therapeutic consequences. It considers patellar instability and patellar maltracking or the complete loss of patellar tracking and differentiates into 5 types. Type 1: patellar dislocation without maltracking or instability with a low risk of redislocation. Type 2: high risk of redislocation, no maltracking. Type 3: instability and maltracking; reasons for maltracking are a) soft tissue contracture, b) patella alta, c) pathological tibial tuberosity trochlear groove (TTTG) distance, c) valgus deformities and e) torsional deformities. Type 4: massively unstable floating patella, which is based on a high-grade trochlear dysplasia. Type 5: maltracking without instability.

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

BACKGROUND

Closing-wedge distal femoral osteotomy (CWDFO)-combined with medial reefing and lateral release, if necessary- has been used to treat recurrent patellar dislocation (RPD) with genu valgum.

PURPOSE

To evaluate the clinical and radiologic outcomes of surgical treatment with CWDFO for treatment of RPD with genu valgum.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Fourteen consecutive patients (23 knees) with RPD and genu valgum were treated with CWDFO. Patients with a minimum 2-year follow-up period were eligible for this study. Patients with prior failed surgery were also eligible. Radiographic evaluation was performed with mechanical femorotibial and lateral distal femoral angle. The radiographic parameters presenting patellar positions and pathologic abnormalities associated with RPD were evaluated. Chondral lesion changes in second-look arthroscopic examination were examined, and clinical outcomes (eg, occurrence of redislocation, range of motion, and clinical scores) were assessed pre- and postoperatively at a minimum of 2 years.

RESULTS

At a mean follow-up of 30.7 months (range, 25-62 months), the mean mechanical femorotibial and mechanical lateral distal femoral angles changed significantly from valgus 5° (range, 2°-11°) to varus 3° (2°-11°; P < .001) and from 83° (range, 78°-86°) to 89° (84°-92°; P < .001), respectively. The mean patellar congruence angle improved from 40° lateral (range, 20°-53° lateral) to 4° medial (23° medial to 21° lateral; P < .001), as did the lateral patellofemoral angle from 26° (range, 8°-62°) to 9° (0°-15°; P < .001). Computed tomography scans showed that the mean distance of patellar lateral shift decreased from 13.5 mm (range, 4-22 mm) to 2.0 mm (-4 to 5 mm; P < .001). The mean tibial tubercle to trochlear groove distance significantly decreased from 20.4 to 13.5 mm ( P < .001), while the Caton-Deschamps ratio did not change significantly after surgery ( P = .984). Chondral lesions of the patella and trochlear groove significantly improved or were maintained. None of the patients experienced subluxation or redislocation after surgery. Patellar instability symptoms also improved, as validated by radiographic and other clinical outcomes.

CONCLUSION

CWDFO combined with medial reefing and lateral release successfully treated RPD with genu valgum for a minimum follow-up of 2 years, with improved patellar alignment and stability.

Distal Femoral Varus Osteotomy for the Management of Valgus Deformity of the Knee

Distal femoral varus osteotomy is a well-described treatment option for patients with valgus malalignment associated with a variety of underlying conditions. This procedure may be the definitive treatment option in active patients with isolated lateral compartment osteoarthritis or posttraumatic arthritis. It may be a useful concomitant procedure in young patients with lateral meniscus deficiency, focal chondral defects, chronic medial collateral ligament insufficiency, and/or patellofemoral instability. Distal femoral varus osteotomy can be performed with medial closing wedge or lateral opening wedge techniques. Variable outcomes and complication rates have been reported. A framework for the use of distal femoral varus osteotomy can aid the orthopaedic surgeon in the evaluation and treatment of patients with symptomatic valgus malalignment.

Patellofemoral dysbalance and genua valga: outcome after femoral varisation osteotomies

INTRODUCTION

Patellofemoral dysbalance may be caused by trochlear dysplasia, an elevated TTTG distance, femoral or tibial torsional deformities, patella alta, or a genu valgum. The surgical procedure for the treatment of a genu valgum is varisation osteotomy, usually in the femoral aspect. Several authors believe that a genu valgum is one cause of patellofemoral dysbalance, but studies about the outcome of the treatment with a varisation osteotomy are rare.

MATERIALS AND METHODS

Nineteen knees in 18 patients, aged on average 28 (16-52) years were investigated in a retrospective study. The patients had symptoms of patellofemoral instability or anterior knee pain due to a genu valgum, without symptoms of a lateral femorotibial compartment. All patients underwent a femoral varisation osteotomy. The diagnostic investigation prior to surgery included full-leg radiographs and torsional angle CT scans. The pre-surgery and follow-up investigation included the visual analog scale (VAS), the Kujala score, the Japanese Knee Society score, the Lysholm score.

RESULTS

The mean duration of follow-up was 44(10-132) months. The mean preoperative mechanical valgus was 5.6° (range 4-10°). Twelve patients mentioned patellar instability as the main symptom while 14 mentioned anterior knee pain. No redislocation occurred in the follow-up period. Anterior knee pain on the VAS (p value < 0.001) was significantly reduced (5.6-2.1). The Japanese Knee Society score improved from 87 to 93 (p value 0.013) points, the Kujala score improved significantly from 72 to 87 (p value 0.009), and the Lysholm score significantly from 76 to 92 (p value < 0.001).

CONCLUSION

Genua valga can lead to patellofemoral dysbalance, treatment of this condition is femoral varisation osteotomy. In this study, patellofemoral stability was achieved and anterior knee pain was significantly reduced. Significant improvements in clinical scores proved the success of the treatment.

LEVEL OF EVIDENCE

IV, case series.

Medial Closing-Wedge Distal Femoral Osteotomy with Medial Patellofemoral Ligament Imbrication for Genu Valgum with Lateral Patellar Instability

A varus-producing distal femoral osteotomy (DFO) is an effective technique for the treatment of lateral patellar instability (LPI) in patients with concomitant moderate to severe valgus malalignment. Patellar maltracking and subluxation are corrected via neutralization of some of the laterally directed forces on the patella due to the valgus deformity. This can be accomplished with a distal femoral lateral opening-wedge or medial closing-wedge osteotomy and medial soft tissue stabilization. A medial closing-wedge osteotomy offers the advantages of immediate weight bearing and a single incision in cases requiring patellofemoral soft tissue stabilization. In this article, we describe our preferred operative technique for a medial closing-wedge DFO using a femoral locking plate and medial patellofemoral ligament imbrication for the correction of LPI.

Open Wedge Distal Femoral Osteotomy: Accuracy of Correction and Patient Outcomes

BACKGROUND

There is a renewed interest in joint preservation surgery, and lateral opening wedge distal femoral osteotomy (DFO), a joint-preserving procedure, has been used to treat symptomatic genu valgum when the deformity originates in the distal femur.

QUESTIONS/PURPOSES

This study aimed to measure the accuracy of lateral opening wedge DFO in achieving deformity correction using radiographic parameters. In addition, the ability of lateral opening wedge DFO to improve patient outcomes as measured by Short Form Health Survey (SF-36) scores and American Academy of Orthopedic Surgeons (AAOS) lower limb module (LLM) scores leading to successful joint preservation was assessed.

METHODS

The clinical charts and radiographs of 28 consecutive patients that underwent 41 DFOs (15 unilateral and 13 staged bilateral) using a locking plate construct were retrospectively reviewed. The mean age of patients undergoing DFO was 44 years (range 22-72), and 22 of the patients were female. The mean follow-up was 26 months (range 12-57 months). Preoperative and postoperative radiographs were evaluated for mechanical axis deviation (MAD), lateral distal femoral angle (LDFA), and the patella congruence angle (PCA). These measurements were compared to determine the accuracy of deformity correction. Clinical outcomes were assessed with preoperative and postoperative SF-36 and AAOS LLM, as well as Oxford knee scores at follow-up.

RESULTS

The accuracy of deformity correction was 95%. The MAD significantly improved from 25.3 mm lateral to the midline to 8 mm medial to the midline (p < 0.01). The LDFA significantly improved from 83.4° to 91.7° (p < 0.01). The PCA significantly improved from 30.4° lateral to 5.7° lateral (p = 0.02). Mean SF-36 scores significantly improved from 37.5 to 50.2 (p = 0.01); mean LLM scores improved from 71.6 to 85.9 (p = 0.021), and the mean postoperative Oxford knee score was 35 ± 6.2 (range 23-46). No patients required total knee arthroplasty at the time of final follow-up.

CONCLUSION

Opening wedge lateral DFO is a reliable procedure for the treatment of valgus knee malalignment with or without arthritic changes in the lateral compartment. Deformity correction is accurate, and patient outcomes reveal significant improvement after surgery. Longer follow-up is required to access the survivorship of this procedure.

A Combined Closing Wedge Distal Femoral Osteotomy and Medial Reefing Procedure for Recurrent Patellar Dislocation with Genu Valgum

PURPOSE

Recurrent patellar dislocation is often associated with genu valgum. The purpose of this study was to analyze the short-term results of single-incision, closing-wedge distal femoral osteotomy (CWDFO) combined with medial reefing and lateral release for recurrent patellar instability with genu valgum.

MATERIALS AND METHODS

Combined CWDFO/medial reefing/lateral release was performed on 10 knees. Clinical evaluation was based on pre- and postoperative Knee Society Score (KSS) and Kujala patellofemoral score. Radiographic evaluation was performed with reference to the weight-bearing line (WBL), the femorotibial angle (FTA), and the mechanical lateral distal femoral angles in the knee-standing view.

RESULTS

At a mean follow-up of 20±11.7 months (range, 12-42 months), KSS scores improved significantly, from 46.7±5.2 preoperatively to 87±4.4 postoperatively (p<0.001), as did the Kujala score, from 44±8 preoperatively to 86.6±6.8 postoperatively (p<0.001). The WBL decreased significantly, from 76±7% preoperatively to 41±11% postoperatively (p<0.001). The FTA was improved significantly, from 12.7±1.7° preoperatively to 4±4° postoperatively (p<0.001), as was the mLDFA, from 83±4° preoperatively to 91±1.3° postoperatively (p<0.001).

CONCLUSION

Use of single-incision CWDFO combined with medial reefing and lateral release prevents patellar dislocation, corrects deformity, and improves clinical outcomes.

Patellar instability treated with distal femoral osteotomy

BACKGROUND

Patellar instability can cause significant disability in both pediatric and adult patients, and it is associated with several factors including genu valgum. In this study, we describe the role of a lateral opening wedge distal femoral osteotomy (DFO) combined with lateral retinacular release in addressing genu valgum with associated patellar instability. The rationale for this approach is to medialize the patellar tendon insertion and decrease the Q angle with DFO.

METHODS

A consecutive series of patients were studied, and our outcomes of interest included improvements in radiographic measures and patient outcomes. Radiographic improvement was assessed using patella congruency angle (PCA), mechanical axis deviation (MAD), and lateral distal femoral angle (LDFA). Patient outcomes were assessed using Oxford Knee scores, KOOS-PS scores, VAS pain scores, and Kujala scores.

RESULTS

We studied eight patients (10 knees) that underwent a lateral opening wedge DFO for genu valgum and patellar instability. Mean follow-up duration was 27 months. PCA improved from 30.4° lateral preoperatively to 5.7° lateral postoperatively (p=0.016). Similarly, MAD improved from 33.1mm lateral to 6.5mm medial, and LDFA improved from 82.4° to 92.7° after surgery (p=0.002). There were significant improvements in VAS pain and Kujala scores after surgery (p<0.05), and a trend towards improvement in KOOS-PS scores (p=0.14). The mean Oxford Knee score at follow-up was 36.25.

CONCLUSION

There is an important relationship between mechanical alignment and patellar instability. Lateral opening wedge DFO is an effective treatment for patellar instability in patients with genu valgum.

Prospective comparative study of two methods for fixation after distal femur corrective osteotomy for valgus deformity; retrograde intramedullary nailing versus less invasive stabilization system plating

INTRODUCTION

The aim of this study was to compare the radiological and functional results of two different methods of fixation for the correction of femoral valgus deformities.

METHODS

Patients who had undergone osteotomy and correction of a valgus deformity from 2007 to 2013 were prospectively followed. Thirty three patients (20 females, 13 males) with 39 lower limbs were included in the study. Seventeen lower limbs were treated with retrograde intramedullary nailing (IMN) and 22 with less invasive stabilization system plating. Standing orthoroentgenograms of the lower limbs were taken pre-operatively and at the final follow-up. mLDFA, aLDFA, mechanical axis deviation (MAD) were measured in this orthoroentgenograms. Knee osteoarthritis outcome score (KOOS) and knee range of motion were used pre-operatively and at the final follow-up as part of the evaluation of the clinical results. All patients duration of surgery, length of hospital stay were assessed. Operations were performed by two orthopedic surgeons. The choice of correction method for each patient was determined by the surgeon. Pre-operative and post-operative values were simultaneously measured by two additional orthopedic surgeons.

RESULTS

The mean age of the patients was 26.2 years (18.0-51.0) in the plating group and 29.3 years (18.0-55.0) in the nailing group. Patients in the plating and nailing groups were followed up for 24.0 (12.0-60.0) and 27.8 (12.0-60.0) months. All patients were followed for a minimum of 12 months. No significant differences were observed between the groups in terms of age, sex, or duration of follow-up (p > 0.05) Comparison of the pre- and post-operative mLDFA, aLDFA, MAD, length of hospital stay, and duration of surgery between the plating group and nailing group, no significant difference was observed between the groups (p > 0.05). However, patients treated with retrograde IMN had significantly better post-operative results in terms of the KOOS and range of motion of the knee according to plating group (p < 0.05).

CONCLUSION

Retrograde IMN does not provide a radiological advantage over the LISS plating technique for valgus deformity but retrograde IMN and correction offered better functional results in cases of femoral valgus deformity than did the LISS plating method.

A new classification system of patellar instability and patellar maltracking

To date there is no classification of patellar dislocations considering clinical and radiological pathologies. As a result many studies mingle the dislocation's underlying pathologies, so that there are no consistent therapy recommendations. It is this article's objective to introduce a patellar dislocation classification based on the current literature to allow for the application of a structured diagnosis and treatment algorithm. The classification is based on instability criteria as well as on clinical and radiological analyses of maltracking and on loss of patellar tracking. There are five types of patellar instability and maltracking. The rare type 1 is a simple (traumatic) patellar dislocation without maltracking and instability with a low risk of redislocation. Type 2 has a high risk of redislocation after primary dislocation; there is no maltracking. Here, a stabilising operation (in most cases MPFL reconstruction) is indicated and sufficient. Type 3 shows both instability and maltracking. Maltracking is mainly caused by: (a) soft tissue contracture, (b) patella alta, (c) pathological tibial tuberosity-trochlea groove distance, (d) valgus deviations and (e) torsional deformities. Stabilisation by means of isolated MPFL reconstruction is not sufficient in these types and additional osseous corrective surgeries are required to achieve physiological patellar tracking and to prevent redislocation. Type 4 features a highly unstable "floating patella" with complete loss of tracking caused by severe trochlear dysplasia. Therapy of choice is trochleoplasty, and if necessary combined with bony and soft-tissue procedures. Type 5 shows a patellar maltracking without instability. Maltracking can only be fixed by means of corrective osteotomy. The classification is referenced to current literature and each type is introduced by a case example. The resulting treatment consequence is also presented.

Surgical treatment of congenital patellar dislocation in skeletally mature patients: surgical technique and case series

BACKGROUND

Congenital patellar dislocation is a rarely encountered condition and is readily treated in childhood to prevent lasting disability, knee pain, decreased range of motion and ambulation problems. This condition is very rarely seen in skeletally mature patients, and the treatment of the condition represents a challenge to the orthopedic surgeon.

SURGICAL TECHNIQUE AND METHODS

Patients were treated with soft tissue reconstruction and tibial tubercle transfer with or without a prior medial close-wedge distal femoral osteotomy, depending on the degree of valgus deformity. We, then, searched the database of our orthopedics center for cases of congenital patellar dislocation in skeletally mature patients who were surgically treated. We collected a total of five knees and analyzed the cases according to the type of surgery performed and difference between pre- and postoperative functions.

RESULTS

Five knees with congenital patellar dislocation were treated. The mean age of the patients was 29.6 years, and mean follow-up time was 4.3 years. Mean preoperative range of motion was 65°, and it increased to a mean of 105.5° after surgical treatment. The mean preoperative Kujala score was 29.2 and increased to 67.2 after surgical treatment.

DISCUSSION

Congenital patellar dislocations that are allowed to proceed to adulthood are difficult to treat, and surgical treatment depends on the degree of deformity of the patella and of the knee joint. This study shows that surgical treatment is able to correct the deformity and provide better knee function.

Distal femoral osteotomy

Osteotomies around the knee are well-recognized treatments for unloading the affected compartment in cases of lower limb malalignment. There are few papers in the literature describing the outcomes of distal femoral osteotomy (DFO), as compared with the studies reporting on high tibial osteotomy (HTO), probably because valgus malalignment is less common than the varus one. There is still debate as to what the correct indication is and which surgical techniques lead to the best outcomes in performing a DFO. Besides, it is still controversial whether patellofemoral arthritis should be considered as a contraindication to performing a DFO, as well as in HTO. In this article, we will summarize the indications for DFO, the surgical techniques reported in the literature, and their outcomes.