Prevailing disagreement in the treatment of complex patellar instability cases: an online expert survey of the AGA Knee-Patellofemoral Committee.

PURPOSE: To evaluate the current state of knowledge and potential controversies in the treatment of patellofemoral instability among orthopaedic/trauma surgeons in the German-speaking countries. METHODS: An online survey consisting of 32 questions and three fictitious cases was sent to members of the AGA-Society for Arthroscopy and Joint Surgery. Surgeons were defined by our senior authors as high-volume or low-volume surgeons, depending on the number of their cases. The treatment of 25% of patients with patellofemoral instability and/or the performance of 50 patellofemoral instability cases per year distinguishes high- from low-volume surgeons in this study. RESULTS: The online questionnaire was completed by 541 experienced knee surgeons from Germany (78%), Austria (10.9%), Switzerland (10.4%) and other countries (0.7%). Most surgeons prefer MPFL reconstruction as surgical intervention in patients with recurrent patellar instability (64-81%). Sixty percent of high-volume surgeons as compared to 21.8% of low-volume surgeons have ever performed a trochleoplasty. Of the overall respondents, 25% would not perform any surgical treatment on adolescents with patellar instability and an open growth plate. Of all responding surgeons, 95% would not treat patellofemoral instability with an isolated lateral release. This corresponds to recent literature showing poor outcome of its strictly isolated application. CONCLUSION: This study provides an overview of the current management of acute and recurrent patellofemoral instability in the German-speaking countries. Results show the surgeons' awareness for highly demanding surgical possibilities for complex patellar instability cases. However, disagreement among surgeons still prevails when it comes to selecting individual multimodal treatment options. This highlights the need for treatment guidelines and algorithms for patellofemoral instability. LEVEL OF EVIDENCE: V.

Isolated medial patellofemoral ligament reconstruction for patella instability is insufficient for higher degrees of internal femoral torsion.

PURPOSE: A medial patellofemoral ligament reconstruction (MPFL) with an additional derotational femoral osteotomy is suggested for patients suffering from patellar instability and an increased internal femoral torsion (IT). This biomechanical study investigated whether an isolated MPFL reconstruction could restore patellofemoral biomechanics for 10° and 20° relatively increased internal femoral torsion. METHODS: Eight fresh-frozen cadaver knees were tested on a specially designed knee simulator, which bend the knee from 0° to 90° flexion. Patellar motion (tilt and shift) and patellofemoral pressure (pressure shift, mean and peak pressure) were evaluated for 0°, 10° and 20° of IT with a native and reconstructed MPFL. RESULTS: An isolated MPFL reconstruction, compared to a native MPFL with the same femoral torsion showed a significant medial shift of the center of force (10° IT p < 0.001; 20° IT p = 0.02) and patella shift (10° and 20° IT p < 0.001) but no significant change in patella tilt (10° IT n.s.; 20° IT n.s.) for 10° and 20° IT. There was a significant medial shift in the center of force for 10° IT (10° IT p = 0.04) and a non-significant lateral shift for 20° IT (20° IT n.s.) in comparison to the native MPFL with 0° of femoral torsion. Patella shift was directed medially for 10° IT (10° IT p = 0.002). In knee flexion angles up to 30°, the patella remained more lateral for 20° IT and showed a different motion pattern (20° IT n.s.). Patella tilt showed a significant lateral tilt for 10° and 20° IT (10° IT p = 0.01; 20° IT p = 0.002). CONCLUSION: MPFL reconstruction as an isolated therapy only appears to be reasonable for 10° increased IT. While for an increased IT of 20°, a lateralizing force vector remains and an additional femoral derotational osteotomy is recommendable. These findings may assist surgeons in the decision making of surgical procedures in patients suffering from patella instability.

[Anatomical double-bundle reconstruction of the medial patellofemoral ligament with a gracilis autograft]. / Anatomische Rekonstruktion des medialen patellofemoralen Bands mit gedoppelter Gracilissehne.

OBJECTIVE: Elimination of patellofemoral instability by reconstruction of the medial patellofemoral ligament (MPFL) with a gracilis autograft. INDICATIONS: Recurring lateral luxation and subluxation of the patella, tibial tuberosity-trochlear groove distance (TTTG) < 20 mm, persistent positive apprehension test in up to 45° of flexion, low grade trochlear dysplasia. CONTRAINDICATIONS: Traumatic luxation of the patella without anatomical risk factors, isolated treatment if TTTG > 20 mm, and isolated treatment for high-grade trochlear dysplasia (type B, C, D). SURGICAL TECHNIQUE: Supine postion. Stripping of the gracilis tendon. Drilling of two tunnels into the medial margin of the patella. Insertion of both tendon ends into the tunnels and fixation with resorbable screwlocks. Undermining of the fascia of the medial oblique vastus muscle and insertion of the tendon loop into the femoral point of insertion located at the medial epicondyle. Preparation of the femoral point of insertion and drilling of the femoral tunnel. Insertion of the graft into the femoral tunnel. Positioning of the knee in 30° of flexion. Positioning of the patella and fixation of the graft with a resorbable screw. POSTOPERATIVE MANAGEMENT: Two weeks of partial weight bearing. Knee orthesis for 6 weeks. Passive motion up to 60° of flexion for the first 2 weeks. Three weeks postoperatively unrestricted motion exercises, strengthening of the quadriceps muscle. Unlimited activity is possible 3 months postoperatively. RESULTS: The method presented in this manuscript was performed on 32 patients with recurring patellar luxation; 27 patients were available for clinical assessment at 1 year postoperatively. There were no recorded events of reluxation; the Kujala score increased on average from 61 points preoperatively to 93 points postoperatively.

The relationship between trochlear dysplasia and medial patellofemoral ligament rupture location after patellar dislocation: an MRI evaluation.

The medial patellofemoral ligament (MPFL) and the native trochlear geometry represent two of the most critical components of patellofemoral stability. We sought to define the relationship between trochlear dysplasia and MPFL rupture location in patients with documented patellar dislocations. We hypothesized that patients with lower grades of trochlear dysplasia would have patellar based MPFL ruptures, while patients with higher grade dysplasia would have femoral-sided ruptures. We reviewed post-injury MRIs of 59 patients with documented patella dislocation. Information gathered included: type of trochlear dysplasia in the axial plane MRI, location of MPFL rupture, patellar height ratio, tibial tuberosity to trochlear groove distance (TTTG), number of dislocations prior to MRI, and time between the latest patella dislocation and the MRI. Statistical calculations utilized the Chi-Square-Test. We classified 11 cases as a dysplasia type A, 35 as a type B, 11 as a type C, and 2 cases as a trochlear dysplasia type D. In 7 patients (12%) the MPFL rupture was patella based, in 18 patients (31%) intra-ligamentous, in 33 cases (56%) femoral sided and in one case no MPFL could be identified. In contrast to our original hypothesis, the type of trochlear dysplasia does not appear to be related to the rupture location of the MPFL after patellar dislocation. According to our results, it is not possible to presume the location of the MPFL rupture based on assessment of the trochlear morphology. Therefore, a MRI is mandatory for final indication of any surgery.

T2 assessment and clinical outcome following autologous matrix-assisted chondrocyte and osteochondral autograft transplantation.

OBJECTIVE: Both, matrix-assisted chondrocyte transplantation (MACT) and osteochondral autograft transplantation (OCT), are applied for treatment of articular cartilage defects. While previous clinical studies have compared the respective outcome, there is no such information investigating the ultrastructural composition using T2 mapping comparing cartilage T2 values of the repair tissue (RT). METHODS: Eighteen patients that underwent MACT or OCT for treatment of cartilage defects at the knee joint (nine MACT, nine OCT) were matched for gender (one female, eight male pairs), age (33.8), body mass index (BMI) (28.3), defect localization, and postoperative interval (41.6 months). T2 assessment was accomplished by T2 maps, while the clinical evaluation included the Lysholm and Cincinnati knee scores, a visual analogue scale (VAS) for pain, the Tegner activity scale, and the Short Form-36. RESULTS: Global T2 values of healthy femoral cartilage (HC) were similar among groups, while T2 values of the RT following MACT (46.8ms, SD 8.6) were significantly lower when compared to RT T2 values after OCT (55.5ms, SD 6.7) (P=0.048). MACT values were also significantly lower in comparison to HC (52.5ms, SD 7.9) within MACT patients (P=0.046), while OCT values were significantly higher compared to HC (49.9ms, SD 5.1) within OCT patients (P=0.041). The clinical outcome following MACT was consistently superior to that after OCT while only the Lysholm score reached the level of significance (MACT 77.0, OCT 66.8; P=0.04). CONCLUSION: These findings indicate that MACT and OCT result in a different ultrastructural outcome, which is only partially represented by the clinical picture.

Osteochondral defect repair after implantation of biodegradable scaffolds: indirect magnetic resonance arthrography and histopathologic correlation.

BACKGROUND: Biodegradable scaffolds have become an important option in the treatment of osteochondral defects. Therefore, accurate and reproducible monitoring of scaffold repair tissue is crucial. PURPOSE: To assess the feasibility of indirect magnetic resonance (MR) arthrography in determining the quality of osteochondral repair after scaffold implantation using an MR imaging (MRI) scoring and grading system with histology as reference. MATERIAL AND METHODS: Osteochondral defects created at ovine condylar facets were treated with either a commercial poly (DL-lactide-co-glycolide) (PLG) scaffold or a modified softer one (n=6/group; 87% and 55% of the elastic modulus of ovine subchondral bone, respectively). Empty defects at the contralateral condyle served as control group. A 1.5T MRI scan was performed after 6 months with proton density (PD)-weighted (w) fat-saturated (fs) fast spin-echo (FSE), T1-w two-dimensional (2D), and 3D fs gradient echo (GE) sequences 30 min after intravenous Gd-DTPA administration and passive joint movement. Two independent radiologists evaluated the repair tissue. The MR findings were correlated with histological findings. RESULTS: MRI and histological grading correlated well (10/12 cases). The stiff-scaffold group showed significantly superior repair in comparison to the control group (P<0.05). The 3D fs GE sequence proved to be most valuable in evaluating morphologic status. Complete defect filling and integration, intact surface and isointense signal to the adjacent native cartilage, subchondral incorporation with bone marrow edema, and graft plug enhancement were associated with a good histological outcome. Histologically, we found a smooth fibrocartilaginous layer and osseous replacement of the scaffold. Incomplete cartilage repair and irregular subchondral structures on the MRI correlated histologically with fibrocartilage-like repair and subchondral sclerosis, due to substantial degradation of the scaffold. CONCLUSION: Indirect MR arthrography is an accurate, noninvasive monitoring tool in the follow-up of scaffold implants. The MRI scoring and grading system allows reliable assessment of normal and pathological repair, with high correlation to histological findings.

Indirect MR-arthrography in osteochondral autograft and crushed bone graft with a collagen membrane--correlation with histology.

OBJECTIVE: To analyze the spectrum of findings in indirect MR-arthrography following osteochondral autograft transfer system (OATS) and crushed bone graft using a magnetic resonance imaging (MRI) scoring and grading system in relation to histology as the standard of reference. MATERIALS AND METHODS: Iatrogenic lesions were set at ovine condylar facets (n=6/group), treated with OATS or crushed bone graft. 1.5 T MRI was performed 6 months after surgery using PD-weighted (w fat saturated (fs) fast spin echo (FSE), T1-w 2D, and 3D fs gradient echo (GE) sequences 30 min. after i.v. Gd-DTPA administration and passive joint exercise. The repair tissue was evaluated by two independent radiologists. The MR findings were compared to histology. RESULTS: In all cases, MRI and histologic grading correlated well and showed significant superior repair in OATS at 6 months (p<0.05), reproducing the original articular contour and a good subchondral restoration. FsT1-w3DGE proved most appropriate identifying characteristic post-operative findings: the OATS group demonstrated bone marrow edema at the donor site and the graft/host interface showed significant enhancement in indirect MR-arthrography, indicating fibrocartilage. After crushed bone graft, we found an irregular structure and significant contrast uptake, consistent with remnants of bone grafts surrounded by inflammatory tissue. CONCLUSION: Indirect MR-arthrography is an accurate, non-invasive monitoring tool following OATS and crushed bone graft as the MRI scoring and grading system allows a reliable evaluation of normal and pathological osteochondral repair with a high histologic correlation.

CT changes after trochleoplasty for symptomatic trochlear dysplasia.

Trochlear dysplasia is an important risk factor for patellar instability. Because of a decreased trochlear depth in combination with a low lateral femoral condyle, the patella cannot engage properly in the trochlea. Trochleoplasty is a surgical procedure, which strives to correct such bony abnormalities. The aim of this study was to describe morphological features of trochlear dysplasia and the corrective changes after trochleoplasty on CT scan. The study group consists of 17 knees with trochlear dysplasia having undergone trochleoplasty for recurrent patellofemoral dislocation at a mean age of 22.4 years. The evaluation consisted in pre- and postoperative measurements on the proximal and distal trochlea on transverse CT scans in order to determine the morphological features. We measured the transverse position and depth of the trochlear groove, the transverse position of the patella, the ratio between the posterior patellar edge and the trochlear groove, the lateral patellar inclination angle, the sulcus angle, and the lateral trochlear slope. The trochlear groove lateralised a mean of 6.1 mm in the proximal aspect and 2.5 mm in the distal aspect of the trochlea, while the patella medialised a mean of 5 mm. Preoperatively the patella was lateral in relation to the trochlear groove in 13 cases, neutral in two cases, and medial in two cases. Postoperatively it was lateral in four cases, in neutral position in seven cases, and medialised in six cases, referenced to the trochlear groove. The trochlear depth increased from 0 to 5.9 mm postoperatively in the proximal aspect of the trochlea, and from 5.5 to 8.3 mm postoperatively in the distal trochlea. The lateral patellar inclination angle decreased from a mean of 21.9 degrees to a mean of 7.8 degrees . The sulcus angle decreased from a mean of 172.1 degrees to a mean of 133 degrees in the proximal trochlea and from a mean of 141.9 degrees to a mean of 121.7 degrees in the distal trochlea. The lateral trochlear slope changed from 2.8 degrees to 22.7 degrees in the proximal and from 14.9 degrees to 26.9 degrees in the distal part of the trochlea. In the CT scan patients with trochlear dysplasia demonstrated a poor depth, or even a flat or convex trochlea with a greater sulcus and lateral trochlear slope angle, a lateralised patella to the trochlear groove with poor congruency, and a greater lateral patellar inclination angle. Trochleoplasty can correct the pathological features of trochlear dysplasia by surgically creating more normal anatomy. The goal of this surgical procedure is to steepen and lateralise the trochlear groove for a better engagement of the patella.

Clinical and radiological outcome of medial patellofemoral ligament reconstruction with a semitendinosus autograft for patella instability.

BACKGROUND: Recurrent patellar instability is a common problem after dislocation. The medial patellofemoral ligament (MPFL) contributes 40-80% of the total medial restraining forces. This study assessed the clinical and radiological outcome after a follow-up of 4 years after linear MPFL reconstruction using an ipsilateral Semitendinosus tendon autograft. STUDY DESIGN AND METHODS: 15 knees in 12 patients were examined with a mean of 47 months after linear reconstruction of the MPFL at a mean age of 30 years. 3 knees underwent previous surgery. 3 patients had mild trochlear dysplasia grade I or II, according to the classification of Dejour. If preoperative tibial tuberosity-trochlear groove distance (TTTG) was more than 15 mm, patients underwent additional medialisation of the tibial tuberosity (n=8) creating a similar postoperative situation for all patients. All patients were available for a postoperative evaluation, which consisted of a subjective questionnaire, the Kujala score, and the recording of potential patellar redislocation and apprehension. Patellar height and tilt was measured on plain radiographs. Postoperative CT scans were performed in patients with an additional tibial tuberosity-transfer. RESULTS: Postoperatively, one patient reported on recurrent bilateral redislocation. Physical examination however revealed no findings. Three knees presented with persistent patellar apprehension. Thirteen knees had improved subjectively after surgery. The mean Kujala score improved significantly from 55.0 to 85.7 points. The patellar tilt decreased significantly from 11.3 degrees to 9.2 degrees. Four knees had patella alta preoperatively, but only two at the latest follow-up visit. Previous surgery or additional trochlear dysplasia had no influence on the clinical outcome. CONCLUSION: MPFL reconstruction improves clinical symptoms, reduces the patellar tilt substantially, and may correct patella alta. Additional mild trochlear dysplasia did not compromise the outcome; however, this fact needs further attention in a larger study group.

[Operative therapy of osteochondral lesions of the talus with autologous cartilage-bone transplantation]. / Operative Therapie von osteochondralen Läsionen am Talus mit autologer Knorpel-Knochen-Transplantation.

Since 1996 we have gained experience in the development and clinical application of the OATS technique in 167 cases. Operative management, technical demands and early results of osteochondral cylindrical autograft plugs at the talus are presented. Between April 1996 and November 2000 we treated 39 patients (21 male, 18 female) with an average age of 28.4 years (range: 16-57 years) for osteochondral defects with an average size of 8 x 15 mm-20 x 15 mm at the medial (n = 31) and lateral (n = 6) talar dome as well as at the distal tibia (n = 2) with an OATS technique. Indications were osteochondral defects after trauma in 12 patients (med., n = 5; lat., n = 5; dist. tibia n = 2) and osteochondrosis dissecans (grades III and IV) in 27 patients (med., n = 26; lat., n = 1). The donor site was the proximal lateral femoral condyle in all patients. An additional osteotomy of the malleolus was necessary in 30 patients. All patients were scored pre- and postoperatively by a Lysholm Bruns score and monitored by postoperative MRI. The follow-up extended for an average of 19.6 months (6-42). The Lysholm score for all patients rose from 62 points (range: 20-77) up to 92 points (range: 63-100). There was no correlation between patients with and without an osteotomy of the malleolus. The postoperative MRI showed a complete incorporation and vitality of the transplanted cylinders as well as a congruence of the joint surface. Complications were pain in three cases in the region of the osteotomy, which decreased after removal of the screws, and synovialitis in one case. One patient reported femoropatellar pain for about 4 weeks. The OATS technique achieves encouraging results in limited osteochondral defects in the talar dome even in preoperated osteochondral defects. Because of the mostly posterior localization of the defect zone, osteotomy of the malleolus is necessary in most cases. Harvesting the donor cylinders from the ipsilateral knee joint by mini-arthrotomy shows a low mortality. The OATS technique is a suitable, causal and cost-effective therapy, which can possibly prevent and at least delay the development of an arthrosis.