A novel approach for joint line restoration in revision total ankle arthroplasty based on the three-dimensional registration of the contralateral tibia and fibula.

PURPOSE: The use of total ankle arthroplasty (TAA) is increasing over time, as so will the need for revision TAAs in the future. Restoration of the ankle joint line (JL) in revision TAA is often difficult due to severe bone loss. This study analyzed the accuracy of a three-dimensional (3D) registration of the contralateral tibia and fibula to restore the ankle joint line (JL) and reported side-to-side differences of anatomical landmarks. METHODS: 3D triangular surface models of 96 paired lower legs underwent a surface registration algorithm for superimposition of the mirrored contralateral lower leg onto the original lower leg to approximate the original ankle JL using a proximal, middle and distal segment. Distances of the distal fibular tip, anterior and posterior medial colliculus to the JL were measured and absolute side-to-side differences reported. Anterior lateral distal tibial angle (ADTA) and lateral distal tibial angle (LDTA) were measured. RESULTS: Mean JL approximation was most accurate for the distal segment (0.1 ± 1.4 mm (range: -3.4 to 2.8 mm)) and middle segment (0.1 ± 1.2 mm (range: -2.8 to 2.5 mm)) compared to the proximal segment (-0.2 ± 1.6 mm (range: -3.0 to 4.9 mm)) (p = 0.007). Distance of the distal fibular tip, the anterior, and posterior medial colliculus to the JL, ADTA and LDTA yielded no significant side-to-side differences (n.s.). CONCLUSION: 3D registration of the contralateral tibia and fibula reliably approximated the original ankle JL. The contralateral distal fibular tip, anterior and posterior medial colliculi, ADTA and LDTA can be used reliably for the planning of revision TAA with small side-to-side differences reported. LEVEL OF EVIDENCE: IV.

Treatment outcomes of patients with Cutibacterium acnes-positive cultures during total joint replacement revision surgery: a minimum 2-year follow-up.

INTRODUCTION: Periprosthetic joint infection (PJI) is a devastating complication following total joint replacement (TJR). Cutibacterium acnes (C. acnes) is a low virulent skin commensal, commonly found during TJR revision surgery for "aseptic" causes. The purpose of the present study was to report the treatment outcomes of patients with C. acnes contamination or infection in the presence of a TJR treated with a revision surgery ± implant exchange ± prolonged (≥ 8 weeks) postoperative antibiotics. METHODS: Medical records of patients with at least one positive C. acnes culture in intraoperative tissue samples or sonication fluid from a TJR revision surgery between January 2005 and December 2014 were retrospectively evaluated. The primary endpoint was infection eradication according to Delphi criteria. The diagnostic accuracy of preoperative TJR aspiration regarding the diagnosis of C. acnes PJI was also investigated. RESULTS: A total of 52 TJR (28 shoulders, 17 hips, 7 knees) in 52 patients (35 males, 17 females) with an average age of 63 ± 11 (33-86) years were included. At an average follow-up of 67 ± 33 (24-127) months, the infection eradication of C. acnes PJI was 97% regardless of the surgical treatment or administration of prolonged postoperative antibiotics. The incidence of unsuspected C. acnes PJI was 28.8%. The sensitivity and specificity of preoperative joint aspiration in detecting C. acnes PJI were 59% and 88%, whereas the PPV and NNV were 83% and 67%, respectively. CONCLUSION: Infection eradication of C. acnes PJI was very high at a minimum follow-up of 24 months, suggesting that C. acnes PJI could be adequately treated with a combination of revision surgery and prolonged postoperative antibiotics. The preoperative diagnosis of C. acnes PJI might be challenging with more than one-quarter of patients presenting without suspicion of C. acnes PJI. The appropriate treatment of patients with a single positive culture remains still unclear. A negative TJR aspiration should not rule out a C. acnes PJI, especially in the presence of clinical correlates of infection. LEVEL OF EVIDENCE: Retrospective case-control study, Level III. IRB APPROVAL: Kantonale Ethikkommission Zürich, BASEC Nr.:2017-00567.

Three-dimensional analysis for quantification of knee joint space width with weight-bearing CT: comparison with non-weight-bearing CT and weight-bearing radiography.

OBJECTIVE: To compare computer-based 3D-analysis for quantification of the femorotibial joint space width (JSW) using weight-bearing cone beam CT (WB-CT), non-weight-bearing multi-detector CT (NWB-CT), and weight-bearing conventional radiographs (WB-XR). DESIGN: Twenty-six participants prospectively underwent NWB-CT, WB-CT, and WB-XR of the knee. For WB-CT and NWB-CT, the average and minimal JSW was quantified by 3D-analysis of the minimal distance of any point of the subchondral tibial bone surface and the femur. Associations with mechanical leg axes and osteoarthritis were evaluated. Minimal JSW of WB-CT was further compared to WB-XR. Two-tailed p-values of <0.05 were considered significant. RESULTS: Significant differences existed of the average medial and lateral JSW between WB-CT and NWB-CT (medial: 4.7 vs 5.1 mm [P = 0.028], lateral: 6.3 vs 6.8 mm [P = 0.008]). The minimal JSW on WB-XR (medial:3.1 mm, lateral:5.8 mm) were significantly wider compared to WB-CT and NWB-CT (both medial:1.8 mm, lateral:2.9 mm, all p < 0.001), but not significantly different between WB-CT and NWB-CT (all p ≥ 0.869). Significant differences between WB-CT and NWB-CT existed in participants with varus knee alignment for the average and the minimal medial JSW (p = 0.004 and p = 0.011) and for participants with valgus alignment for the average lateral JSW (p = 0.013). On WB-CT, 25% of the femorotibial compartments showed bone-on-bone apposition, which was significantly higher when compared to NWB-CT (10%,P = 0.008) and WB-XR (8%,P = 0.012). CONCLUSION: Combining WB-CT with 3D-based assessment allows detailed quantification of the femorotibial joint space and the effect of knee alignment on JSW. WB-CT demonstrates significantly more bone-on-bone appositions, which are underestimated or even undetectable on NWB-CT and WB-XR.

Increased femoral antetorsion correlates with higher degrees of lateral retropatellar cartilage degeneration, further accentuated in genu valgum.

PURPOSE: The role of increased femoral antetorsion (femAT) as a contributor to patellofemoral (PF) osteoarthritis (OA) is unknown. The purpose of this study was to investigate whether increased femAT was associated with advanced cartilage degeneration in the lateral PF joint. METHODS: Patients who underwent complete radiographic workup for surgical intervention due to OA in any knee joint compartment were included. Cartilage morphology according to the International Cartilage Repair Society (ICRS) cartilage lesion classification system in the PF joint, femoral and tibial torsion, frontal leg axis, and tibial tuberosity-trochlear groove (TT-TG) distance were assessed. Increased femAT was defined as > 20° according to previous reports. RESULTS: A total of 144 patients were included. Ninety-seven patients had a femAT of < 20° and 45 of > 20°. A significant odds ratio (OR) was found for lateral retropatellar (OR 3.5; p = 0.02) ICRS grade 3 and 4 cartilage degeneration and increased femAT ≥ 20°. In the medial PF compartment, increased femAT had an inverse effect (OR 0.16; p = 0.01). No significant ORs were found for TT-TG distance, tibial torsion, or leg axis. The lateral retropatellar ICRS grade showed a linear correlation to increased femAT values. In valgus knees, isolated lateral PF OA had an even more pronounced correlation to increased femAT (p = 0.004). CONCLUSION: Increased femAT showed higher grades of lateral retropatellar cartilage degeneration, which was even more pronounced in valgus knees. LEVEL OF EVIDENCE: Cohort study: Level III.

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.

Total and unicondylar knee arthroplasty are equivalent treatment options in end-stage spontaneous osteonecrosis of the knee, and the size of the lesion has no influence on the results.

PURPOSE: The purpose of the present study was to compare total (TKA) and unicondylar (UKA) knee arthroplasty for spontaneous osteonecrosis of the knee (SONK), and to investigate potential correlations to radiographic parameters. METHODS: All consecutive patients with a magnetic resonance imaging (MRI) proven SONK treated with either TKA or UKA between 2002 and 2018 were analysed. The primary outcomes were postoperative complications and failure rates. Functional assessment included Knee Society Score (KSS), WOMAC Score, and range of motion. A novel three-dimensional measurement method was established to determine the size of the osteonecrotic lesion. All outcome parameters were correlated to the size of the necrotic lesion using Spearman's rank correlation. RESULTS: The two treatment groups (34 TKAs, 37 UKAs) did not differ regarding age, body mass index, and ratio of the volume of the necrotic lesion to the volume of the femoral condyle (n.s.). At a mean follow-up of 6.6 years, patients with UKA had better functional outcomes compared to patients with a TKA (WOMAC Score 1.0 vs. 1.6, p = 0.04; KSS pain 86 vs. 83, n.s), with a similar complication rate. No correlation was found between necrotic lesion size and failure rate (n.s.). CONCLUSION: UKA is a valuable treatment option for SONK leading to good functional results and a low failure rate. In case of a surgeon's concern regarding implant anchorage, TKA represents an equivalent solution. The MR-tomographic size of the osteonecrotic lesions seems to have no influence on the results. LEVEL OF EVIDENCE: III.

Diagnostic accuracy of 99mTc-antigranulocyte SPECT/CT in patients with osteomyelitis and orthopaedic device-related infections: A retrospective analysis.

OBJECTIVES: Conventional imaging techniques are routinely used in the diagnostic work-up of patients with suspected osteomyelitis or orthopaedic implant-associated infections. Hybrid nuclear medicine imaging techniques are a suitable alternative to routine imaging modalities as they provide anatomical and functional information within one procedure. Our study investigated the performance of anti-granulocyte SPECT/CT using 99mTc-labelled monoclonal antibodies in the diagnosis of osteomyelitis and orthopaedic implant-associated infections. METHODS: In this retrospective analysis, we included patients with 99mTc-antigranulocyte SPECT/CT acquired in the context of a suspected bone and joint infection. All patients underwent routine diagnostics and/or had a clinical follow-up of at least 12months. RESULTS: 26 episodes were included. Fifteen exams were performed for suspected osteomyelitis, and 11 for suspected orthopaedic implant-associated infection. SPECT/CT was ordered most often if standard diagnostic tests or conventional imaging modalities remained inconclusive. The overall sensitivity and specificity for the diagnosis of an infection were 77.8% and 94.1%, respectively. The positive predictive value was 87.5% and the negative predictive value 88.9%. Diagnostic accuracy was 88.5%. CONCLUSIONS: 99mTc-antigranulocyte SPECT/CT imaging has a high accuracy in the diagnosis of osteomyelitis and orthopaedic implant-associated infections and is a suitable non-invasive diagnostic tool if standard diagnostic examinations are inconclusive or not applicable.

Clinical and radiological results after one hundred fifteen MPFL reconstructions with or without tibial tubercle transfer in patients with recurrent patellar dislocation-a mean follow-up of 5.4 years.

PURPOSE: Medial patellofemoral ligament reconstruction (MPFLR) shows low recurrent rates and high satisfaction. Reports on outcome at mid-term follow-up in a large cohort with or without tibial tubercle transfer (TTT) are scarce. METHODS: One hundred six patients (115 knees; 24.3 ± 8.7 years) with recurrent patellar dislocation underwent MPFLR with ipsilateral gracilis autograft and were included in this retrospective follow-up study. In 43 knees, simultaneous TTT was performed for patellar maltracking due to patella alta or increased tibial tubercle trochlear groove distance (TT-TG). Kujala and subjective knee scores were recorded pre- and post-operatively. RESULTS: Eighty-seven percent of the patients were satisfied at a mean follow-up of 5.4 ± 3.1 years. The Kujala score increased in 81.7% of all knees from 50.9 to 76.2 points (p < 0.01). Patients with a decreased Kujala score were not different in terms of follow-up time, age, trochlear dysplasia, or post-operative patellar height. The decline was related to an increase in pain, whereas functional scores remained identical. There were six patients with persisting instability, three with patellar re-dislocation. Re-operation was necessary in 24 patients (21.2%), mainly for implant removal after TTT and loss of flexion. Performing TTT had no significant influence on the subjective outcome. Patients with more than eight years of follow-up (n = 27) did not show any difference in the subjective outcome parameters, or in osteoarthritis progression. CONCLUSION: MPFLR with and without TTT is a reliable treatment option for recurrent patellar dislocation without deterioration at mid-term follow-up. Persisting pain is a major post-operative issue that seems to be unrelated to patellofemoral anatomy.

Inflammatory disorders mimicking periprosthetic joint infections may result in false-positive α-defensin.

OBJECTIVES: The antimicrobial peptide α-defensin has recently been introduced as a potential 'single' biomarker with a high sensitivity and specificity for the preoperative diagnosis of periprosthetic joint infections (PJIs). However, most studies assessed the benefits of the test with exclusion of patients with rheumatic diseases. We aimed to evaluate the α-defensin test in a cohort study without exclusion of people with inflammatory diseases. METHODS: Between June 2016 and June 2017, we prospectively included cases with a suspected PJI and an available lateral flow test α-defensin (Synovasure®) in synovial fluid. We compared the test result to the diagnostic criteria for PJIs published by an International Consensus Group in 2013. RESULTS: We included 109 cases (49 hips, 60 knees) in which preoperative α-defensin tests had been performed. Among these, 20 PJIs (16 hips, four knees) were diagnosed. Preoperative α-defensin tests were positive in 25 cases (22.9%) with a test sensitivity and specificity of 90% and 92.1% (95% CI 68.3%-98.8% and 84.5%-96.8%, respectively), and a high negative predictive value of 97.6% (95% CI 91.7%-99.4%). We interpreted seven α-defensin tests as false positive, mainly in cases with inflammatory rheumatic diseases, including crystal deposition diseases. CONCLUSIONS: A negative synovial α-defensin test can reliably rule out a PJI. However, the test can be false positive in conjunction with an underlying non-infectious inflammatory disease. We therefore propose to use the α-defensin test only in combination with Musculoskeletal Infection Society criteria and assessment for crystals in synovial aspirates.

[Indications for joint replacement : Knee arthroplasty]. / Indikationen zum Gelenkersatz : Knieendoprothese.

Current demographic trends with an increasing number of older patients, have led to a rising number of patients with higher demands on performance. Osteoarthritis in younger patients caused by abnormal forms or accidents also pose new challenges for medical professionals in the orthopedic field. As a rule of thumb, all conservative therapeutic possibilities should be exhausted before starting a surgical intervention. The main aims of surgery are to reduce pain, increase mobility and quality of life. In order to qualify for total knee arthroplasty (TKA) patients must fulfil major and minor criteria; however, after TKA approximately one fifth of patients are not satisfied with the result. In order to reduce this rate, indications should be narrowly set and expectations should be thoroughly discussed with the patient prior to an intervention. The high degree of dissatisfaction must be improved by intensifying efforts in further research.

Patellar tendinopathy with intratendinous alteration on MRI may be related to patellofemoral dysplasia.

Patellar tendinopathy (PT) is a frequent overuse injury of the extensor knee apparatus, whereas as up to 30% of the athletes might suffer from persisting symptoms during their entire career. In the present case-control study, 47 patients (30.8 ± 11.4 years) with PT with intratendinous alteration (PTita) of a minimum of ≥25% of the axial surface on MRI and minimum Blazina score of II (pain during without limiting sports activity) were included; MR images were analyzed for trochlear geometry, patellar height/tilt, and tibial tubercle-trochlear groove distance (TT-TG). The control group (CG) comprised 87 age- and gender-matched patients without history of anterior knee pain or lateral patellar instability. It was hypothesized that patients with PT might be related to patellofemoral dysplasia. It was found that the patella was significantly higher in patients with PT compared to the CG (patellotrochlear index [PT-I]: 0.33 vs 0.37, P = .014; Insall-Salvati index [InSa]: 1.18 vs 1.07, P = .004). PT-I was above the cut-off value in 10.6% of PT knees (CG 5.7%, P = .27), and InSa in 42.6% (CG 21.8%, P = .012). TT-TG was significantly higher in patients with PT compared to CG (12.0 mm vs 9.9 mm, P = .002); however, TT-TG was only pathologic (>20 mm) in one patient. The trochlear facet ratio was above the cut-off value in 55.3% of PT patients and 23% of CG (P < .001), and was significantly greater in patients with PT (0.39 ± 0.09) than CG (0.48 ± 0.1, P < .001). Knees with PT have significantly more morphological characteristics of patellofemoral instability, which needs to be considered especially in recurrent or treatment-refractive cases.

[Patellofemoral instability]. / Patellainstabilität.

Patellofemoral instability is an extremely limiting pathology in young and active patients. Anatomical reasons for patellar instability, such as high-riding patella, elevated distance from the tibial tuberosity to trochlear groove (TTTG), trochlear dysplasia, insufficient medial patellofemoral ligament (MPFL) and malpositioning of the axes and torsion can lead to chronic patellofemoral instability and must be thoroughly analyzed. The first dislocation can be treated conservatively, with the exception of an osteochondral defect. In the case of recurrent dislocation of the patella surgery is indicated, with good results regarding stability and less clear results regarding the influence on pain. The surgical approach is determined by the anatomical pathology. High-riding patella and elevated TTTG can be corrected by osteotomy of the tibial tuberosity and severe trochlear dysplasia by trochleoplasty. Insufficient MPFL can be reconstructed very successfully. The influence and correction of the axes and torsion are not yet fully understood and must be studied further.

Visual-palpatory versus fluoroscopic intraoperative determination of the femoral entry point in medial patellofemoral ligament reconstruction.

PURPOSE: Malpositioning of the femoral entry point in reconstruction of the medial patellofemoral ligament (MPFL) can lead to abnormal and painful patellar kinematics and loss of flexion. Determination of this point is usually performed by palpation of anatomic landmarks. Accuracy of this method has not yet been investigated. The hypotheses were: 1. palpatory method is not as accurate as fluoroscopically guided method using established radiological criteria; 2. accuracy correlates with surgical experience. METHODS: Three surgeons of varying experience defined the femoral entry point for the MPFL by palpation in ten cadaveric legs. The blinded procedures were repeated three times, and subjective difficulty of the determination was recorded. Results were documented by fluoroscopy on a true lateral radiograph. The accuracy was assessed using established radiological criteria. Surgical experience was correlated with the results, and confounding or interacting variables were assessed. RESULTS: Mean deviation from the correct zone for the femoral entry point was 3.5 mm (range 0-18 mm). Twenty-nine percent of all palpatory determinations were inside the correct zone, 47 % were within 5 mm distance from the correct zone, and 23 % were further than 5 mm apart from the correct zone ("outliers"). No significant difference was found between surgeons of varying experience. No correlation was observed between subjective difficulty of the procedure and accuracy of determination. CONCLUSIONS: The validity of the isolated palpatory determination of the femoral entry point in MPFL reconstruction seems to be insufficient, regardless of surgical experience. Derived from this study, fluoroscopic guidance is used in our clinic by default.

Radiographic accuracy in TKA with a CT-based patient-specific cutting block technique.

PURPOSE: Patient-specific instrumentation (PSI) technology for the implantation of total knee arthroplasty (TKA) has a rising interest in the orthopaedic community. Data of PSI are controversially discussed. The hypothesis of this paper is that the radiological accuracy of CT-based PSI is similar to the one of navigated TKA published in the literature. METHODS: Since 2010, all 301 consecutively performed PSI TKAs (GMK MyKnee©) were included in this study. The radiological assessment consisted in a preoperative and postoperative standard X-ray and long-standing X-ray. Changes from the planned to the definitively implanted component size were documented. Postoperative analysis included limb alignment and position of femoral and tibial components (for varus/valgus and flexion or tibial slope). RESULTS: The postoperative average hip-knee-ankle angle was 180.1° ± 2.0°. In the frontal plane a total of 12.4 % of outliers >3°, for the tibial components 4.1 % of outliers >3° and for the femoral components 4.8 % of outliers >3° were measured. A total of 12.3 % of outliers for posterior tibial slope and 9 % of outliers >3° for the femoral flexion were noted. 10.8 % of the 602 planned size components were adapted intraoperatively. CONCLUSION: Although it is still unknown which limb axis is the correct one for the best clinical result, a technology providing the aimed axis in a most precise way should be chosen. Comparing the outcome of the current study with the data from the literature, there does not seem to be any difference compared to computer-assisted surgery. LEVEL OF EVIDENCE: IV.

[Surgical dislocation of the hip for the treatment of femoroacetabular impingement. Technique and results]. / Therapie des femoroazetabulären Impingements über die chirurgische Hüftluxation. Technik und Ergebnisse.

Surgical dislocation of the hip is a safe and established technique for treating femoroacetabular impingement. The complication rate is low, and if the correct technique that respects the blood supply is used, femoral head necrosis does not occur. The most frequent complications are minor ectopic bone formation and nonunion of the greater trochanter. Surgical treatment includes the correction of femoral and acetabular pathology. Clinically, in approximately 75-80% of cases a good-to-excellent result can be obtained. However, patients with advanced degenerative changes (exceeding stage 1 osteoarthritis using the Tönnis score) have worse outcomes. It has also been shown that preservation of the labrum has a significant influence on both clinical outcome and progression of osteoarthritis: It seems that preservation of the labrum is mandatory.

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.