Accuracy of femoral tunnel positioning in medial patellofemoral ligament reconstruction: anatomic insertion leads to better clinical outcome.

PURPOSE: The medial patello-femoral ligament (MPFL) is considered the primary restraint against patellar dislocation and its reconstruction is indicated in recurrent patellar instability. An anatomical positioning of MPFL femoral insertion is recommended to achieve satisfactory clinical outcomes and prevent osteoarthritis (OA) due to an altered kinematics. The purpose of the study was first to assess the relationship between correct femoral tunnel position and better clinical outcomes and lower patellofemoral osteoarthritis rate. Second, correlation of outcomes with factors potentially affecting the results, such as the type of graft, patellar height and trochlear dysplasia. METHODS: Fifty-three patients (58 knees) who underwent MPFL reconstruction between 2009 and 2018 by a senior knee surgeon were retrospectively evaluated. Knee radiographs were performed before surgery, 12 months later and at last follow-up to assess trochlear dysplasia, patellar height and patellofemoral OA. The tibial tuberosity-trochlear groove (TT-TG) value was measured on a CT scan. The accuracy of graft positioning was evaluated on sagittal radiographs according to Schöttle et al. Subjective outcomes were collected before surgery, at 12 months and at last follow-up using several validated scores. RESULTS: Forty-six patients (51 knees) with a mean age of 24.1 ± 7.4 years were included in the study. Mean follow-up was 8.9 ± 2.1 years. A significant improvement in all clinical scores was observed at 12 months and final follow-up. Anatomic Insertion (AI) of reconstructed MPFL was considered optimal in 33 (64.7%) and sub-optimal in 18 (35.3%) patients. Sub-optimal AI resulted in lower Kujala, IKCD and higher VAS score (p < 0.01); moreover, for every 1 mm distance in any direction from the ideal insertion, a decrease of 0.8 [95% CI (-1.4; -0.2)] in Kujala score and 0.8 [95% CI (-1.3; -0.3)] in IKDC was observed. At final follow-up, 8 patients presented patellofemoral OA Iwano grade 3 (15.7%): although that incidence did not correlate to graft positioning, the use the artificial ligament in all these cases appeared to be significant. CONCLUSION: The present study confirms the importance of an optimal anatomic femoral insertion in MPFL reconstruction, reporting a significant positive correlation between graft positioning and clinical outcome. No significant correlations were found between anatomic insertion and patello-femoral OA development. LEVEL OF EVIDENCE: IV.

3D Knee Trochlear Morphology Assessment by Magnetic Resonance Imaging in Patients With Normal and Dysplastic Trochleae.

BACKGROUND: Trochlear dysplasia is recognized as a significant risk factor for patellar instability, but current imaging modalities fail to allow full visualization and classification of the complex 3-dimensional (3D) anatomy of the trochlea. The purpose of this study was to elucidate primary differences in trochlear morphology between patients with and without patellar instability by utilizing 3D magnetic resonance imaging (MRI) reconstructions of the trochlea. METHODS: An institutional review board-approved retrospective review included 24 patients with a diagnosis of patellar instability and an age-matched and sex-matched control population of 12 patients. 3D models of the femoral trochlea were created from MRI images and measurements were performed. 3D measurements were trochlear groove volume and surface area that were normalized to the femoral width. 2D measurements were performed throughout the length of the trochlea including the bony and cartilaginous sulcus angles as well as the bony and cartilaginous trochlear depths. Differences were also assessed between sex, skeletal maturity, and trochlear dysplasia severity. RESULTS: Surface topography of the trochlea varied significantly based on location with the trochlea becoming progressively more flat proximally away from the notch (P<0.05). Patients with patella instability had reduced trochlear volumes and trochlear depths compared with control patients (P<0.05). These differences were more pronounced with the cartilaginous measurements as well as more proximally within the trochlea. Patients with high-grade dysplasia had greater reductions in trochlear volumes and depth especially proximally in the trochlea (P<0.05). Once femoral size was standardized, minimal differences were observed based on sex or skeletal maturity (P>0.05). CONCLUSIONS: Novel 3D MRI reconstructions demonstrated that measurements of trochlear morphology varied significantly between patients with and without patellar instability. When trochlear dysplasia is present, it appears to affect the majority of the trochlear surface, but preferentially the proximal extent. Future trochlear dysplasia classification systems may benefit from assessment of articular cartilage surface measures rather than primarily osseous structure measurements. LEVEL OF EVIDENCE: Level III-case-control prognostic study.

Clinical Outcomes and Predictive Factors for Failure With Isolated MPFL Reconstruction for Recurrent Patellar Instability: A Series of 211 Reconstructions With a Minimum Follow-up of 3 Years.

BACKGROUND: Reconstruction of the medial patellofemoral ligament (MPFL) is widely acknowledged as an integral part of the current therapeutic armamentarium for recurrent patellar instability. The procedure is often performed with concomitant bony procedures, such as distalization of the tibial tuberosity or trochleoplasty in the case of patella alta or high-grade trochlear dysplasia, respectively. At the present time, few studies have evaluated the clinical effectiveness of MPFL reconstruction as an isolated intervention. PURPOSE: To report the clinical outcomes of isolated MPFL reconstruction in cases of patellar instability and to identify predictive factors for failure. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A retrospective analysis of prospectively collected data was performed, including all patients who had undergone isolated MPFL reconstruction between January 2008 and January 2014. Preoperative assessment included the Kujala score, assessment of patellar tracking ("J-sign"), and radiographic features, such as trochlear dysplasia according to Dejour classification, patellar height with the Caton-Deschamps index (CDI), tibial tubercle-trochlear groove distance, and patellar tilt. The Kujala score was assessed postoperatively. Failure was defined by a postoperative patellar dislocation or surgical revision for recurrent patellar instability. RESULTS: A total of 239 MPFL reconstructions were included; 28 patients (11.7%) were uncontactable and considered lost to follow-up. Thus, 211 reconstructions were analyzed with a mean follow-up of 5.8 years (range, 3-9.3 years). The mean age at surgery was 20.6 years (range, 12-48 years), and 55% of patients were male. Twenty-seven percent of patients had a preoperative positive J-sign, and 93% of patients had trochlear dysplasia (A, 47%; B, 25%; C, 15%; D, 6%). The mean CDI was 1.2 (range, 1.0-1.7); mean tibial tubercle-trochlear groove distance, 15 mm (range, 5-30 mm); and mean patellar tilt, 23° (range, 9°-47°). The mean Kujala score improved from 56.1 preoperatively to 88.8 ( P < .001). Ten failures were reported that required surgical revision for recurrent patellar instability (4.7%). Uni- and multivariate analyses highlighted 2 preoperative risk factors for failure: patella alta (CDI ≥1.3; odds ratio, 4.9; P = .02) and preoperative positive J-sign (odds ratio, 3.9; P = .04). CONCLUSION: In cases of recurrent patellar instability, isolated MPFL reconstruction would appear to be a safe and efficient surgical procedure with a low failure rate. Preoperative failure risk factors identified in this study were patella alta with a CDI ≥1.3 and a preoperative positive J-sign.

Clinical and Radiological Predictors of Functional Outcome After Isolated Medial Patellofemoral Ligament Reconstruction at Midterm Follow-up.

BACKGROUND: Isolated medial patellofemoral ligament reconstruction (iMPFLR) is increasingly used for the surgical treatment of recurrent patellofemoral instability. PURPOSE: The purpose of this study was to identify the clinical and radiological predictors that can significantly influence the functional outcomes after an iMPFLR. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A total of 107 patients (112 ligament reconstructions) who underwent iMPFLR were evaluated with a mean ± SD follow-up of 59 ± 33 months (range, 12-123 months). Functional International Knee Documentation Committee (IKDC) and Kujala scores were assessed preoperatively and every 12 months. Radiological assessment of patellar height and tilt (Laurin angle, Merchant angle, Maldague classification) and computed tomography (CT) scan measurement of patellar tilt (contracted and relaxed quadriceps) and tibial tubercle-trochlear groove distance were performed preoperatively and at 6 months. Femoral tunnel position was assessed following the criteria formulated by Schöttle. The amount of femoral tunnel widening was measured by means of 3-dimensional CT scan at 6 months. Predictors were determined from univariate and multivariate regression analyses integrating clinical and radiological criteria pre- and postoperatively. The dependent variable was defined as the difference between pre- and postoperative scores. RESULTS: Between pre- and postoperative measurement at last follow-up, a significant improvement for IKDC and Kujala functional scores was observed (Kujala: 57 ± 11.3 to 87 ± 12.9, P < .001; IKDC: 47.8 ± 13.1 to 79 ± 15.8, P < .001). Demographics (age, body mass index, sex), dislocation characteristics (number of dislocations, time between first dislocation and surgery, age at first dislocation, mechanism of first dislocation, knee side), clinical data (frontal limb alignment, hyperlaxity, recurvatum, pre- and postoperative range of motion), and complications (quadriceps atrophy, complex regional pain syndrome) did not influence functional scores. The predictors of lower improvement in functional scores included small correction of the patellar tilt reported on the CT scan measurement, malpositioning of the femoral tunnel, and a widening of this tunnel near the medial cortex. Malpositioning of the femoral tunnel was correlated with tunnel widening, and patients with anterior and proximal malpositioning experienced stiffness in flexion. CONCLUSION: Overall, iMPFLR demonstrated good outcomes. Predictors influencing the functional results were identified. Less improvement in clinical outcome was reported for patients with a high preoperative patellar tilt and only a small correction in tilt and for those who had femoral tunnel malpositioning, which was correlated with tunnel widening.

Isolated Medial Patellofemoral Ligament Reconstruction for Patellar Instability Regardless of Tibial Tubercle-Trochlear Groove Distance and Patellar Height: Outcomes at 1 and 2 Years.

BACKGROUND: It is unclear which patients with recurrent patellar instability require a bony procedure in addition to medial patellofemoral ligament (MPFL) reconstruction. PURPOSE: To report 1- and 2-year outcomes of patients after isolated MPFL reconstruction performed for patellar instability regardless of patellar height, tibial tubercle-trochlear groove (TT-TG) distance, or trochlear dysplasia. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: All patients with recurrent patellar instability and without significant unloadable chondral defects (Outerbridge grade IV), cartilage defects (especially inferior/lateral patella), previous failed surgery, or pain >50% as their chief complaint were prospectively enrolled beginning March 2014. All patients underwent primary, unilateral, isolated MPFL reconstruction regardless of concomitant bony pathology for treatment of recurrent patellar instability. Information on recurrent subjective instability, dislocations, ability to return to sport (RTS), and outcome scores was recorded at 1 and 2 years. TT-TG distance, patellar height (with the Caton-Deschamps index), and trochlear depth were measured. RESULTS: Ninety patients (77% female; mean ± SD age, 19.4 ± 5.6 years) underwent MPFL reconstruction between March 2014 and August 2017: 72 (80%) reached 1-year follow-up, and 47 (52.2%) reached 2-year follow-up (mean follow-up, 2.2 years). Mean TT-TG distance was 14.7 ± 5.4 mm (range, -2.2 to 26.8 mm); mean patellar height, 1.2 ± 0.11 mm (range, 0.89-1.45 mm); and mean trochlear depth, 1.8 ± 1.4 mm (range, 0.05-6.85 mm). Ninety-six percent of patients at 1 year and 100% at 2 years had no self-reported patellofemoral instability; 1 patient experienced a redislocation at 3.5 years. RTS rates at 1 and 2 years were 90% and 88%, respectively. Mean time to RTS was 8.8 months. All patients had clinically and statistically significant improvement in mean Knee injury and Osteoarthritis Outcome Score-Quality of Life (32.7 to 72.0, P < .001), mean International Knee Documentation Committee subjective form (51.4 to 82.6, P < .001), and mean Kujala score (62.2 to 89.5, P < .001). No difference existed between 1- and 2-year outcome scores (all P > .05). CONCLUSION: At early follow-up of 1 and 2 years, isolated MPFL reconstruction is an effective treatment for patellar instability and provides significant improvements in outcome scores with a low redislocation/instability rate regardless of bony pathologies, including TT-TG distance, Caton-Deschamps index, and trochlear dysplasia. Future data from this cohort will be used to assess long-term outcomes.

Gender-related morphological differences in sulcus angle and condylar height for the femoral trochlea using magnetic resonance imaging.

PURPOSE: This study aimed to elucidate the primary differences in trochlear morphology between men and women utilizing three-dimensional magnetic resonance image reconstruction of the femoral trochlea. METHODS: Differences in anthropometric femoral trochlea data of 975 patients (825 women, 150 men) were evaluated. The following morphological parameters were measured at three flexion angles (15°, 30°, and 45°) of the femoral trochlea: the sulcus angle, condylar height, and the trochlear groove orientation and mediolateral groove position. RESULTS: The sulcus angle was significantly greater in women than in men at 15° and 45° flexions (P < 0.05). However, there was no gender difference found in the sulcus angle at 30° flexion. Medial and lateral condylar height values were greater in men than in women for the three flexion angles (P < 0.01). The trochlear groove orientation and mediolateral groove position showed no gender-related differences. CONCLUSIONS: Magnetic resonance image reconstruction demonstrated that measurement of trochlear morphology varied significantly between men and women. This study provides guidelines for the design of a suitable femoral component for total knee arthroplasty, considering gender-specific differences in the Korean population. Biomechanical guidelines for total knee arthroplasty in Korean individuals can be optimized using our finding, so as the risk of patellar dislocation to be decreased. Surgeons should be aware of gender differences in femoral trochlear to optimize choice of implant. LEVEL OF EVIDENCE: III.

A combined procedure with Bereiter-type trochleoplasty leads to a stable patellofemoral joint at 5-year follow-up.

PURPOSE: Trochlear dysplasia is a major risk factor predisposing to patellar instability and has been reported to occur in up to 85% of patients with recurrent patellar dislocation. Different operative techniques have been described to correct trochlear dysplasia, including the Bereiter technique, in which subchondral bone is removed and the cartilage can be compressed into a U-shaped groove. The hypothesis was that after a Bereiter-type trochleoplasty combined with medialisation of the tibial tubercle and MPFL reconstruction, patellar pain and instability decreased and anatomic reconstruction can be seen radiographically after 5-year follow-up. METHODS: Between 2004 and 2011, a combined procedure including Bereiter-type trochleoplasty was performed on 21 consecutively included patients (22 knees) with objective patellar instability and severe trochlear dysplasia. Instability and pain were assessed preoperatively and 3, 6, 12, 24 and 60 months postoperatively with the visual analogue scale (VAS) for pain and instability, Kujala, International Knee Documentation Committee Subjective Knee Evaluation (IKDC SKE) and Short Form Health Survey (SF-36). Pre- and postoperatively, a true lateral radiograph was made to investigate the presence of the crossing sign and to measure the trochlear bump and trochlear depth, as well as a sunrise patella view to measure the sulcus angle. RESULTS: VAS pain and instability, Kujala and IKDC SKE improved significantly 5 years after trochleoplasty (p < 0.05). SF-36 showed no significant improvement. None of the patients reported patellar dislocations postoperatively. Sport activities remained limited. Postoperative radiographs showed no crossing sign. There was a significant increase in trochlear depth (p < 0.0001) and also a significant decrease in trochlear bump and sulcus angle (both p < 0.0001). CONCLUSIONS: A combined procedure consisting of Bereiter-type trochleoplasty, medialisation of the tibial tubercle and MPFL reconstruction in patients with objective patellar instability and severe trochlear dysplasia resulted in a clear decrease of pain and instability. Radiological assessment showed anatomical reconstruction. Nevertheless, residual symptoms remain and the possibility of future cartilage damage is uncertain. LEVEL OF EVIDENCE: IV.

Suboptimal patellofemoral alignment is associated with poor clinical outcome scores after primary total knee arthroplasty.

BACKGROUND: Proper patellofemoral alignment is an important goal in total knee arthroplasty (TKA). Acceptable patellar alignment is defined as patellar tilt less than or equal to 5° and patellar displacement less than or equal to 5 mm. Previous studies reported an incidence of post-operative patellar malalignment in TKA from 7 to 35%. However, correlation between patellar malalignment and clinical outcome after TKA remains unclear. The purpose of the present study was to evaluate the effect of patellar tilt and displacement on the clinical outcome of TKA. METHODS: A retrospective review of 138 primary TKAs with a minimum of 2 year follow-up is reported. Pre-operative and post-operative mechanical axis, patellar tilting angle and patellar displacement were measured. Clinical outcomes were evaluated by the knee functional scores including the Knee Society Score (KSS), Knee injury and Osteoarthritis Outcome Score (KOOS), and Western Ontario McMaster University Osteoarthritis Index (WOMAC) at final follow-up. RESULTS: Forty-two (30%) primary TKAs had suboptimal patellofemoral alignment with a patellar tilt angle greater than 5° or lateral patellar displacement of more than 5 mm. There was no statistical difference in pre-operative mechanical axis, pre-operative patellar tilt angle, or pre-operative lateral patellar displacement between the primary TKAs with proper patellofemoral alignment and those with suboptimal alignment. Patients with post-operative patellar tilt or displacement had clinically significant reductions in KSS, KOOS, and WOMAC when compared with patients without post-operative patellar tilt or displacement. The odds of having a fair or poor post-operative result, an odds ratio of 3.4 (95% CI 1.6-7.2) for KSS, 6.4 (95% CI 2.9-14.2) for KOOS, and 5.9 (95% CI 2.6-13.5) for WOMAC, were associated with suboptimal patellofemoral alignment. CONCLUSION: Establishing proper patellofemoral alignment remains an essential goal of primary TKA. There is a strong association between suboptimal post-operative patellofemoral alignment and poor clinical outcome scores after primary TKA.

Heritability of patellar luxation in the Chihuahua and Bichon Frise breeds of dogs and effectiveness of a Swedish screening programme.

Patellar luxation is one of the more common orthopaedic diseases of dogs and is relatively frequent in some toy breeds, including the Chihuahua and Bichon Frise. Using data provided by the Swedish Kennel Club, genetic parameters, including heritability, were estimated for patellar luxation in the Chihuahua from 1999 to 2014 and in the Bichon Frise from 1997 to 2014. The effects of the current screening programmes for patellar luxation in these breeds were evaluated. Patellar luxation was defined as a binary trait, treating dogs as affected or unaffected. The edited data included 7024 records for the Chihuahua and 1071 records for the Bichon Frise. Patellar luxation was analysed using mixed linear and threshold animal models, including fixed effects of sex, birth month, birth year, age at veterinary examination, random effects of the examining veterinary surgeon, genetic effect of the individual and residual. The prevalence of patellar luxation was 23% in the Chihuahua and 12% in the Bichon Frise. Using threshold analysis, estimated heritabilities were 0.25 for the Chihuahua and 0.21 for the Bichon Frise on the observable scale, and 0.46 for the Chihuahua on the underlying scale. It was concluded that there is genetic variation in patellar luxation and that there has been a slight genetic improvement over the study period in the Chihuahua. Further genetic progress would be facilitated by selection using estimated breeding values based on veterinary screening records.

Outcomes of Medializing Tibial Tubercle Osteotomy With Medial Reefing and Vastus Medialis Obliquus Advancement Coupled With Lateral Retinacular Z-Lengthening for Recurrent Patellar Instability.

PURPOSE: Patella-femoral dislocations, although rare, can result in functionally limiting symptoms and limited return to prior activity levels. The purpose of this study is to report outcomes of a three-in-one patellar realignment surgery for treatment of recurrent patellar instability in a young, active duty military population. METHODS: We conducted a retrospective chart review of all patients who underwent our senior author's three-in-one patellar realignment surgery for recurrent patellar instability in the setting of underlying anatomic malalignment. Our primary outcome measure was the rate of recurrent instability. Secondary outcome measures included rate of return to full unrestricted active duty military service and the functional outcome scores. RESULTS: A total of 13 patients with an average follow-up of 16 months were included in this study. During the follow-up period, there were no reported instability events (either dislocation or subluxation). Three (23%) patients were separated secondary to issues with their operative knee and two additional patients were no longer on active duty at time of final follow-up. Six patients had paired (pre- and postoperative) Single Assessment Numerical Evaluation scores which showed a statistically significant improvement (p < 0.05) between the median pre- and postoperative Single Assessment Numerical Evaluation scores of 45 and 85, respectively. CONCLUSION: Our study demonstrates that the described patellar realignment procedure is effective at substantially reducing and possibly eliminating the symptoms of recurrent instability and allows a modest return to unrestricted active duty.

Biomechanical comparison of single- and double-bundle medial patellofemoral ligament reconstruction.

BACKGROUND: Recurrent patellar dislocation is common clinically, primarily in adolescents. However, the biomechanical properties of single- and double-bundle medial patellofemoral ligament (MPFL) reconstruction remain poorly understood. METHODS: Six fresh frozen adult cadaveric knee specimens were obtained for this study. Each specimen was fixed at 0° to test the force needed when the patella was laterally shifted 10 mm at a speed of 0.5 mm/s, and the test was repeated three times. This test was repeated when knee flexion was at 0°, 15°, 30°, 45°, 60°, and 90°. All six specimens were tested in four statuses, including MPFL intact, MPFL torn, single-bundle MPFL reconstruction, and double-bundle MPFL reconstruction. RESULTS: Similar force is required in these MPFL statuses at 0° of flexion, except for the MPFL torn group with a smaller force (45.5 ± 9.6 N, p < 0.05). The force required in the MPFL torn group reduced from 12.8 to 38.8% compared to other groups, at 0°, 15°, 30°, and 45° of flexion angles. At the flexion of 15°, the double-bundle reconstruction group required a statistically greater force (85.9 ± 10.1 N) compared to the single-bundle reconstruction group (74.0 ± 7.9 N). Interestingly, no statistical difference was found at flexions of 60° and 90° in these four groups. CONCLUSIONS: Both single-bundle and double-bundle MPFL reconstruction can restore the stability of the patella. The double-bundle reconstruction has an angular synergy effect that simulates the MPFL wide footprint in the patella, which enables it to have greater capacity to resist patellar dislocation before the patella entering the femoral trochlea at a smaller flexion angle.

The outcomes of the modified Fulkerson osteotomy procedure to treat habitual patellar dislocation associated with high-grade trochlear dysplasia.

BACKGROUND: Habitual patellar dislocation is not common in clinical practice, but it has a deep impact on the patient's lifestyle and movement. There has been no large case-control study on habitual patellar dislocation, and the management of it is still controversial. The aim of this study was to observe the efficacy of the modified Fulkerson procedure on patients with habitual patellar dislocation with high-grade trochlear dysplasia without trochleoplasty and to evaluate the results of this procedure. METHODS: A total of 25 patients who were admitted to our hospital from April 2007 to October 2013 were included: 7 males and 18 females, aged 17-28 years old, with an average age of 21.5 years old, including 21 cases of unilateral dislocation and 4 cases of bilateral dislocation. The tibial tuberosity transfer procedure (internal rotation, medial transfer and elevation osteotomy) and medial patellofemoral ligament (MPFL) reconstruction were performed in all cases of habitual patellar dislocation that were accompanied by trochlea dysplasia. RESULTS: The mean follow-up duration was 36.8 months (range, 25-68 months). A CT scan was performed to compare the tibial tuberosity-trochlear groove distance (TT-TG), the patellar tilt angle (PTA), and the mean Kujala and Lysholm scores before surgery and at follow-up and to measure the angle of internal rotation of the tibial tubercle after surgery. The mean Kujala and Lysholm scores improved significantly (P < 0.05) from 55.65 ± 6.10 and 50.34 ± 6.54 preoperatively to89.24 ± 4.66 and 88.53 ± 4.75, respectively, at follow-up. The tibial tuberosity-trochlear groove distance (TT-TG) decreased significantly (P < 0.05) from 20.24 ± 2.80 mm to 10.50 ± 4.50 mm, and the patellar tilt angle (PTA) decreased significantly (P < 0.05) from28.58 ± 3.28to7.54 ± 5.56. No recurrence was observed, and only one patient had a mild skin infection after surgery. The mean angle of internal rotation of the tibial tubercle was 10 ± 4° after surgery. There were no cases of stiffness. CONCLUSIONS: The modified procedure of tibial tubercle transfer, especially the internal rotation, which can improve the patella stability and knee function, is an effective surgical procedure for the treatment of habitual patellar dislocation associated with high-grade trochlear dysplasia without trochleoplasty. LEVEL OF EVIDENCE: III.

[Current therapy progress on the recurrent patellar dislocation].

Patients who suffer from the recurrent patellar dislocation mainly show the recurrent dislocation of patellar, giving way, most patients have the history of trauma or dysplasia of keen joint. Traditional therapies of recurrent patellar dislocation include medical retinaculum placation, lateral retinaculum release, tibial tubercle osteotomy, femoral trochleoplasty etc. In recent years, with the development of anatomical and biomechanical researches on medial patellofemoral ligament(MPFL), more and more experts focus on the role of MPFL played in preventing the patellar dislocation. The treatment of recovering and correcting patellar tracking through MPFL reconstruction has been increasing gradually. However, till now, there was no therapy which could heal the recurrent patellar dislocation completely. The specific therapies of recurrent patellar dislocation are combination therapies, decided according to the anatomical and biomechanical conditions of patients, for recovering the stability of patients' patellar, the lower limb alignment and the function of keen-joint.

Medial patellofemoral ligament reconstruction for patellar instability following total knee arthroplasty: A review of 6 cases.

INTRODUCTION: Patellar instability is a frequent cause of total knee arthroplasty (TKA) failure. In cases of post-arthroplasty patellar instability, the medial structures may be damaged. The objective of this study was to study the effectiveness of medial patellofemoral ligament (MPFL) reconstruction. We hypothesized that MPFL reconstruction will effectively realign the patella, making it a viable treatment option for managing post-arthroplasty patellar instability. MATERIAL AND METHODS: In this retrospective study of six patients treated by four different surgeons, patients were included if they had a recurring or permanent patellar dislocation after undergoing TKA. Patients were excluded if the patellar instability was painful but did not result in dislocation. Each patient underwent MPFL reconstruction using the gracilis; additional procedures could be performed depending on the diagnosis. One patient required TKA revision because of an abnormally rotated femoral implant. The main outcome measure was the non-recurrence of the dislocation. The IKDC and Kujala functional scores, joint range of motion and patellar tilt on X-rays were analyzed preoperatively and at the last follow-up. RESULTS: At a mean follow-up of 23 months (6-46), none of the patients experienced a recurrence of the patellar dislocation. Only one patient had no improvements in the functional outcome scores. The patellar tilt was reduced in all patients. CONCLUSION: MPFL reconstruction-in isolation or with femoral component revision-is effective at treating post-arthroplasty patellar instability. It has its place in the treatment of patellar dislocation following TKA and its indications must be based on exact analysis of the reasons for the instability. LEVEL OF EVIDENCE: IV - Retrospective cohort study.

Iatrogenic Medial Patellar Instability: An Avoidable Injury.

Iatrogenic medial patellar instability is a specific condition that frequently causes incapacitating anterior knee pain, severe disability, and serious psychological problems. The diagnosis should be suspected in a patient who has undergone previous patellar realignment surgery that has made the pain worse. The diagnosis can be established by physical examination and simple therapeutic tests (e.g., "reverse" McConnell taping) and confirmed by imaging techniques. This iatrogenic condition should no longer exist and could almost be eliminated by avoiding over-release of the lateral retinaculum.

Does degree of trochlear dysplasia and position of femoral tunnel influence outcome after medial patellofemoral ligament reconstruction?

BACKGROUND: The medial patellofemoral ligament (MPFL) is the main restraining force against lateral patellar displacement. It is disrupted after patellar subluxation or dislocation. Reconstruction of the MPFL is frequently performed when nonoperative management fails and the patient experiences recurrent patellar dislocation. PURPOSE: To determine the relationship between the degree of trochlear dysplasia and femoral tunnel position and outcome after MPFL reconstruction. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A total of 68 patients (72 knees) with recurrent dislocation of the patella underwent MPFL reconstruction. The mean follow-up was 31.3 months (range, 13-72 months). Clinical and functional outcomes were recorded using the Kujala, Lysholm, and Tegner scores. Postoperative complications, participation in sporting activity, and overall patient satisfaction were determined. Radiographs were analyzed to evaluate congruence angle, lateral patellofemoral angle, patellar height, trochlear dysplasia, trochlear boss height, and position of the femoral tunnel. RESULTS: The mean Kujala, Lysholm, and Tegner scores postoperatively were 76.2, 73.8, and 3.6, respectively (n = 61). The mean congruence angle (n = 30) improved from 22.5° to 1.0° postoperatively (P = .000038), the lateral patellofemoral angle (n = 30) improved from 7.4° to 7.8° postoperatively (P = .048), and the patellar height (n = 46) using the Caton-Deschamps method improved from 1.1 to 1.0 postoperatively (P = .000016). Mild trochlear dysplasia grade A/B was found in 89% of patients (n = 54), and 11% of patients (n = 7) had severe grade C/D dysplasia. The mean distance from the anatomic insertion of the MPFL to the center of the tunnel was 9.3 mm (range, 0.5-28.2 mm), with 71.7% thought to be within 10 mm of the anatomic position defined by Schottle (n = 46). When patients with high-grade trochlear dysplasia were excluded, anatomically placed femoral tunnels demonstrated significantly better clinical scores than did tunnels not placed anatomically (Kujala score, P = .028; Lysholm score, P = .012). A multivariate logistic regression analysis also demonstrated that the distance of the femoral tunnel from the anatomic position predicted clinical outcome (Kujala score, P = .043; Lysholm score, P = .028). All of the patients with severe trochlear dysplasia (n = 7) suffered from recurrent dislocations postoperatively, compared with only 9.3% of patients (n = 5) with mild trochlear dysplasia (P = .0001). Four patients had patellar fractures postoperatively. Of patients with mild dysplasia, 83% were either very satisfied or satisfied with the outcome of their surgery compared with only 57% with severe dysplasia (P = .05). Of patients with mild trochlear dysplasia, 56% returned to sport postoperatively compared with only 43% of patients with severe trochlear dysplasia (P = .526). CONCLUSION: This study demonstrates the importance of restoration of the anatomic insertion point of the MPFL when performing MPFL reconstruction and proposes that this procedure should not be performed in isolation in patients with high-grade trochlear dysplasia.

Medial patellofemoral ligament (MPFL) reconstruction for the treatment of patellofemoral instability.

Patellofemoral instability can be a disabling problem. Numerous techniques are employed for its treatment. Medial patellofemoral ligament (MPFL) reconstruction in combination with other procedures has been explored by many orthopedic surgeons. The purpose of the study was to determine the effectiveness of isolated MPFL reconstruction in treating the symptoms associated with patellofemoral instability, preventing recurrence of patella dislocation, and returning patients to preinjury level of activity. This is a case series study. We conducted a clinical follow-up study on 56 knees (49 patients) after MPFL reconstruction for recurrent patellar instability with a mean follow-up of 4.3 years (range, 1.1-6.8). A single MPFL reconstruction technique was performed in all cases. Patient outcomes were evaluated using: International Knee Documentation Committee (IKDC) subjective knee form, Tegner activity score, functional hop test, and radiographs. Mean age at time of surgery was 24 years old (range, 13-49). Females comprised 75% of the sample. Mean interval from injury to surgery was 7.2 ± 8.6 years (range, 51 days-37 years). At follow-up, there were no recurrent dislocations reported, patella subluxation in 6 (11%) cases, and radiographic degenerative changes were none to mild in all patients. The series mean IKDC scores at follow-up was 76.3 ± 19.2 (range, 30-99), and Tegner activity scores were 5.6 ± 2.5. MPFL reconstruction is an option for treating the symptoms of patellar instability, preventing recurrent dislocation, and returning patients near to their preinjury level of activity. The level of evidence is IV.

Midterm results of comprehensive surgical reconstruction including sulcus-deepening trochleoplasty in recurrent patellar dislocations with high-grade trochlear dysplasia.

BACKGROUND: Trochlear dysplasia is one of the most consistent anatomic factors that can lead to recurrent patellar dislocations. Various trochleoplasty procedures have been described to treat patellar dislocations in high-grade dysplasia by creating a new congruent trochlea. PURPOSE: To present the midterm efficacy and outcome of the sulcus-deepening trochleoplasty procedure in patients with recurrent patellar dislocations due to high-grade trochlear dysplasia. The clinical evaluation results, the amount of radiological correction, and the prevalence of arthritis were recorded. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: A total of 27 skeletally mature patients (31 knees) with recurrent patellar dislocations due to high-grade trochlear dysplasia without any previous surgery were retrospectively included from September 1993 to September 2006. All patients underwent sulcus-deepening trochleoplasty combined with a bony and/or soft tissue procedure according to concomitant etiological factors to patellar dislocations: medial patellofemoral ligament reconstruction (16.1%), vastus medialis obliquus plasty (83.8%), tibial tuberosity distalization (51.6%), tibial tuberosity medialization (67.7%), and lateral retinaculum release (67.6%). Mean follow-up was 7 years (range, 2-9 years). RESULTS: The mean sulcus angle decreased significantly (P < .01) from 152° ± 16° preoperatively to 141° ± 9° postoperatively, tibial tuberosity-trochlear groove distance decreased significantly (P < .001) from 19 ± 4 mm to 12 ± 5 mm, and patellar tilt decreased significantly (P < .001) from 37° ± 7° to 15° ± 8°. No recurrence was observed, and there was no case of stiffness. Apprehension signs remained positive in 19.3% of the cases, patellar tracking was normal in all cases, and the lateral patellar glide test finding was negative in 96.8%. The mean preoperative International Knee Documentation Committee (IKDC) score was 51 (range, 25-80), and the mean postoperative IKDC score was 82 (range, 40-100) (P < .001), while the mean Kujala score improved from a preoperative 59 (range, 28-81) to 87 (range, 49-100) postoperatively (P < .001). There was no radiographic evidence of patellofemoral arthritis at the latest follow-up. CONCLUSION: Sulcus-deepening trochleoplasty is a valid option for the primary surgical treatment of carefully selected patients with recurrent patellar dislocations with high-grade trochlear dysplasia type B and D. Concomitant etiological factors must be cautiously corrected in an associated procedure. Midterm follow-up showed satisfactory restoration of patellar stability and improvement of knee scores with no complication of subsequent arthritis.

Comparison of 2 different techniques for anatomic reconstruction of the medial patellofemoral ligament: a prospective randomized study.

BACKGROUND: The comparative clinical outcome of anatomic reconstruction of the medial patellofemoral ligament (MPFL) between the Y-graft technique and C-graft technique for chronic patellar instability is unknown. HYPOTHESIS: Anatomic reconstruction of the MPFL with a Y-graft technique (a Y-shaped graft: femoral fixation first with separate tensioning of the 2 bundles) would yield better clinical results than a C-graft procedure (a C-shaped graft: patellar fixation first with simultaneous tensioning of both bundles) for chronic patellar instability. STUDY DESIGN: Randomized controlled trial; Level of evidence, 2. METHODS: Ninety patients with symptomatic chronic patellar dislocations or instability were randomly divided into 2 groups to undergo double-bundle MPFL reconstruction either with the Y-graft technique or C-graft technique. Follow-ups were performed at 3, 6, 12, and 24 months postoperatively. The patellar stability was evaluated with the apprehension test at follow-up. The patellofemoral morphological characteristics were evaluated on axial computed tomography (CT) scans at 30° of knee flexion, and knee function was evaluated using the Lysholm and Kujala scores preoperatively and at 24 months postoperatively. RESULTS: Forty patients in the Y-graft group and 42 patients in the C-graft group were followed for 24 months. No recurrent dislocation or subluxation was reported in either group. On CT scans, congruence angle, patellar tilt angle, lateral patellar angle, and lateral displacement were restored to the normal range. The mean postoperative Lysholm scores for the Y-graft group and C-graft group were 92.3 ± 3.9 and 88.4 ± 6.8, respectively (P = .001). The mean postoperative Kujala scores were 95.9 ± 4.7 and 91.3 ± 9.7 for the Y-graft group and C-graft group, respectively (P = .001), with a good or excellent rate of 97.5% in the Y-graft group compared with 83.3% in the C-graft group (P = .031). CONCLUSION: With no patellar redislocations reported, the Y-graft technique for the double-bundle anatomic MPFL reconstruction achieved statistically better knee function than the C-graft procedure at a minimum 2-year follow-up. However, the increase was less than the minimal clinically important difference, and further research is required to demonstrate its meaningful clinical improvement.

Combined trochleoplasty and medial patellofemoral ligament reconstruction for recurrent patellar dislocations in severe trochlear dysplasia: a minimum 2-year follow-up study.

BACKGROUND: Trochlear dysplasia is an important etiological factor for the development of patellofemoral instability. Because a dislocation of the patella as a result of trochlear dysplasia results in a traumatic disruption of the medial patellofemoral ligament (MPFL), a combined trochleoplasty and patellofemoral ligament reconstruction appears to be the most appropriate procedure to treat patients with severe trochlear dysplasia. HYPOTHESIS: Combined trochleoplasty and anatomic reconstruction of the MPFL will prevent redislocations of the patella and will lead to improved knee function. STUDY DESIGN: Case series; Level of evidence, 3. METHODS: Twenty-three consecutive patients (26 knees) with patellofemoral instability and severe trochlear dysplasia underwent combined trochleoplasty and anatomic reconstruction of the MPFL. Preoperative radiographic examination included anteroposterior and lateral views to assess patella alta. Magnetic resonance imaging was performed to evaluate trochlear dysplasia and the tibial tubercle-trochlear groove (TT-TG) distance. Evaluations included the detection of cartilage injuries, preoperative and postoperative physical examinations, and scores for the visual analog scale (VAS), Kujala knee function, International Knee Documentation Committee (IKDC), activity rating scale (ARS), and Tegner activity scale. RESULTS: The mean age at the time of operation was 19.2 years (range, 15.4-23.6 years). The mean follow-up after operation was 2.5 years after surgery (range, 2.0-3.5 years). No recurrent dislocation occurred postoperatively. Kujala scores improved from 79 to 96, IKDC scores from 74 to 90, and VAS scores from 3 to 1. All improvements were highly statistically significant (P < .01). The activity level according to the Tegner activity scale and the ARS decreased but was not statistically significant (P = .06 and P = .21, respectively). There were 95.7% of the patients who were satisfied or very satisfied with the procedure. CONCLUSION: Combined anatomic reconstruction of the MPFL and trochleoplasty reliably improved the stability of the patellofemoral joint in patients with severe trochlear dysplasia and no or mild degenerative changes. In addition, the described procedure showed significant improvement of knee function and good patient satisfaction without any episode of redislocations of the patella.