Unexpected early loosening of rectangular straight femoral Zweymüller stems with an alumina-reduced surface after total hip arthroplasty-a prospective, double-blind, randomized controlled trial.

BACKGROUND: Alumina particles from the grit blasting of Ti-alloy stems are suspected to contribute to aseptic loosening. An alumina-reduced stem surface was hypothesized to improve osseointegration and show comparable short-term outcomes to those of a standard stem. METHODS: In this prospective, double-blind, randomized trial, 26 standard (STD) and 27 experimental new technology (NT) stems were implanted. The latter were additionally treated by acid etching and ice blasting to remove alumina particles from the grit-blasting process. Follow-up occurred at 12 and 24 months. Bone mineral density (BMD) around the stem was measured by a dual-energy x-ray absorptiometry device (DEXA). Radiographs were reviewed for alterations. Clinical scoring comprised the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Harris Hip Score (HHS). Survival rates were calculated up to 50 months. RESULTS: Lower mean BMD and more severe cortical hypertrophies were found in the NT group. At 12 months, radiolucent lines were observed mostly in the metaphyseal zone for both groups, with a progression tendency in the NT group at 24 months. At 12 months, pain scores and the WOMAC total and physical activity scores were significantly lower in the NT group, without any differences thereafter. The number of NT stem revisions amounted to 6 (24%) and 11 (41%) at 24 and 50 months, respectively. CONCLUSION: In the NT group, unexpected catastrophic failure rates of 41% caused by early aseptic loosening were noted within 50 months. Compared with the STD stems, NT stems lead to poor clinical and radiographic results. LEVEL OF EVIDENCE: II. TRIAL REGISTRATION: NCT05053048.

Optical fibers for endoscopic high-power Er:YAG laserosteotomy.

SIGNIFICANCE: The highest absorption peaks of the main components of bone are in the mid-infrared region, making Er:YAG and CO2 lasers the most efficient lasers for cutting bone. Yet, studies of deep bone ablation in minimally invasive settings are very limited, as finding suitable materials for coupling high-power laser light with low attenuation beyond 2 µm is not trivial. AIM: The first aim of this study was to compare the performance of different optical fibers in terms of transmitting Er:YAG laser light with a 2.94-µm wavelength at high pulse energy close to 1 J. The second aim was to achieve deep bone ablation using the best-performing fiber, as determined by our experiments. APPROACH: In our study, various optical fibers with low attenuation (λ = 2.94 µm) were used to couple the Er:YAG laser. The fibers were made of germanium oxide, sapphire, zirconium fluoride, and hollow-core silica, respectively. We compared the fibers in terms of transmission efficiency, resistance to high Er:YAG laser energy, and bending flexibility. The best-performing fiber was used to achieve deep bone ablation in a minimally invasive setting. To do this, we adapted the optimal settings for free-space deep bone ablation with an Er:YAG laser found in a previous study. RESULTS: Three of the fibers endured energy per pulse as high as 820 mJ at a repetition rate of 10 Hz. The best-performing fiber, made of germanium oxide, provided higher transmission efficiency and greater bending flexibility than the other fibers. With an output energy of 370 mJ per pulse at 10 Hz repetition rate, we reached a cutting depth of 6.82 ± 0.99 mm in sheep bone. Histology image analysis was performed on the bone tissue adjacent to the laser ablation crater; the images did not show any structural damage. CONCLUSIONS: The findings suggest that our prototype could be used in future generations of endoscopic devices for minimally invasive laserosteotomy.

Quantitative Evaluation of the Thickness of the Available Manipulation Volume Inside the Knee Joint Capsule for Minimally Invasive Robotic Unicondylar Knee Arthroplasty.

OBJECTIVE: Developing robotic tools that introduce substantial changes in the surgical workflow is challenging because quantitative requirements are missing. Experiments on cadavers can provide valuable information to derive workspace requirements, tool size, and surgical workflow. This work aimed to quantify the volume inside the knee joint available for manipulation of minimally invasive robotic surgical tools. In particular, we aim to develop a novel procedure for minimally invasive unicompartmental knee arthroplasty (UKA) using a robotic laser-cutting tool. METHODS: Contrast solution was injected into nine cadaveric knees and computed tomography scans were performed to evaluate the tool manipulation volume inside the knee joints. The volume and distribution of the contrast solution inside the knee joints were analyzed with respect to the femur, tibia, and the anatomical locations that need to be reached by a laser-cutting tool to perform bone resection for a standard UKA implant. RESULTS: Quantitative information was determined about the tool manipulation volume inside these nine knee joints and its distribution around the cutting lines required for a standard implant. CONCLUSION: Based on the volume distribution, we could suggest a possible workflow for minimally invasive UKA, which provides a large manipulation volume, and deducted that for the proposed workflow, an instrument with a thickness of 5-8 mm should be feasible. SIGNIFICANCE: We present quantitative information on the three-dimensional distribution of the maximally available volume inside the knee joint. Such quantitative information lays the basis for developing surgical tools that introduce substantial changes in the surgical workflow.

Optimizing deep bone ablation by means of a microsecond Er:YAG laser and a novel water microjet irrigation system.

The microsecond Er:YAG pulsed laser with a wavelength of λ = 2.94 µm has been widely used in the medical field, particularly for ablating dental tissues. Since bone and dental tissues have similar compositions, consisting of mineralized and rigid structures, the Er:YAG laser represents a promising tool for laserosteotomy applications. In this study, we explored the use of the Er:YAG laser for deep bone ablation, in an attempt to optimize its performance and identify its limitations. Tissue irrigation and the laser settings were optimized independently. We propose an automated irrigation feedback system capable of recognizing the temperature of the tissue and delivering water accordingly. The irrigation system used consists of a thin 50 µm diameter water jet. The water jet was able to penetrate deep into the crater during ablation, with a laminar flow length of 15 cm, ensuring the irrigation of deeper layers unreachable by conventional spray systems. Once the irrigation was optimized, ablation was considered independently of the irrigation water. In this way, we could better understand and adjust the laser parameters to suit our needs. We obtained line cuts as deep as 21 mm without causing any visible thermal damage to the surrounding tissue. The automated experimental setup proposed here has the potential to support deeper and faster ablation in laserosteotomy applications.

Surgical treatment of patellofemoral instability using trochleoplasty or MPFL reconstruction: a systematic review.

PURPOSE: Trochleoplasty and reconstruction of the medial patellofemoral ligament (MPFL) are among the most commonly performed surgical treatments in patients with patellofemoral instability. The primary purpose of the study was to perform a systematic literature review on trochleoplasty in the treatment of patients with patellofemoral instability. The secondary purpose was to compare the outcomes with those seen in patients treated after reconstruction of the MPFL. METHODS: A standardised search on search engines was performed. All observational and experimental studies dealing with trochleoplasty were then obtained and reviewed in a consensus meeting. Fifteen articles out of 1543 were included and analysed using the CASP appraisal scoring system. Twenty-five studies on MPFL reconstruction were obtained for comparison. The clinical and radiological outcomes were statistically analysed. RESULTS: Both treatment groups showed significant improvement in outcomes from pre- to post-operatively. The mean post-operative Kujala and the Lysholm scores significantly increased in both groups when compared to preoperatively (trochleoplasty group: Kujala 61.4-80.8 and Lysholm 55.5-78.5; MPFL group: Kujala 46.9-88.8 and Lysholm 59.9-91.1). Post-operatively a positive apprehension test was found in 20 and 8 % of the trochleoplasty and MPFL groups, respectively. No significant differences in redislocation (2 %) and subluxation (5-6 %) rates were found. CONCLUSIONS: This systematic review showed that both trochleoplasty and MPFL reconstruction are able to deliver good clinical outcomes with stable patellofemoral joints. LEVEL OF EVIDENCE: III.

Supramolecular Organization of Collagen Fibrils in Healthy and Osteoarthritic Human Knee and Hip Joint Cartilage.

Cartilage matrix is a composite of discrete, but interacting suprastructures, i.e. cartilage fibers with microfibrillar or network-like aggregates and penetrating extrafibrillar proteoglycan matrix. The biomechanical function of the proteoglycan matrix and the collagen fibers are to absorb compressive and tensional loads, respectively. Here, we are focusing on the suprastructural organization of collagen fibrils and the degradation process of their hierarchical organized fiber architecture studied at high resolution at the authentic location within cartilage. We present electron micrographs of the collagenous cores of such fibers obtained by an improved protocol for scanning electron microscopy (SEM). Articular cartilages are permeated by small prototypic fibrils with a homogeneous diameter of 18 ± 5 nm that can align in their D-periodic pattern and merge into larger fibers by lateral association. Interestingly, these fibers have tissue-specific organizations in cartilage. They are twisted ropes in superficial regions of knee joints or assemble into parallel aligned cable-like structures in deeper regions of knee joint- or throughout hip joints articular cartilage. These novel observations contribute to an improved understanding of collagen fiber biogenesis, function, and homeostasis in hyaline cartilage.

A novel standardized algorithm using SPECT/CT evaluating unhappy patients after unicondylar knee arthroplasty--a combined analysis of tracer uptake distribution and component position.

BACKGROUND: The introduction of a standardized SPECT/CT algorithm including a localization scheme, which allows accurate identification of specific patterns and thresholds of SPECT/CT tracer uptake, could lead to a better understanding of the bone remodeling and specific failure modes of unicondylar knee arthroplasty (UKA). The purpose of the present study was to introduce a novel standardized SPECT/CT algorithm for patients after UKA and evaluate its clinical applicability, usefulness and inter- and intra-observer reliability. METHODS: Tc-HDP-SPECT/CT images of consecutive patients (median age 65, range 48-84 years) with 21 knees after UKA were prospectively evaluated. The tracer activity on SPECT/CT was localized using a specific standardized UKA localization scheme. For tracer uptake analysis (intensity and anatomical distribution pattern) a 3D volumetric quantification method was used. The maximum intensity values were recorded for each anatomical area. In addition, ratios between the respective value in the measured area and the background tracer activity were calculated. The femoral and tibial component position (varus-valgus, flexion-extension, internal and external rotation) was determined in 3D-CT. The inter- and intraobserver reliability of the localization scheme, grading of the tracer activity and component measurements were determined by calculating the intraclass correlation coefficients (ICC). RESULTS: The localization scheme, grading of the tracer activity and component measurements showed high inter- and intra-observer reliabilities for all regions (tibia, femur and patella). For measurement of component position there was strong agreement between the readings of the two observers; the ICC for the orientation of the femoral component was 0.73-1.00 (intra-observer reliability) and 0.91-1.00 (inter-observer reliability). The ICC for the orientation of the tibial component was 0.75-1.00 (intra-observer reliability) and 0.77-1.00 (inter-observer reliability). CONCLUSIONS: The SPECT/CT algorithm presented combining the mechanical information on UKA component position, alignment and metabolic data is highly reliable and proved to be a valuable, consistent and useful tool for analysing postoperative knees after UKA. Using this standardized approach in clinical studies might be helpful in establishing the diagnosis in patients with pain after UKA.

Clinical and radiological long-term outcome after posterior cruciate ligament reconstruction and nonanatomical popliteus bypass.

PURPOSE: The purpose of this study was to analyse the long-term outcome of patients treated for combined posterior cruciate ligament (PCL) and posterolateral corner injuries by combined PCL reconstruction and popliteus bypass according to Mueller or refixation of the popliteus tendon. METHODS: Sixteen patients treated by combined PCL reconstruction and popliteus bypass according to Mueller (n = 7) or refixation of the popliteus tendon (n = 9) were included. A mean follow-up of 24 ± three years was performed using the International Knee Documentation Committee (IKDC) 2000, Lysholm, Tegner and the Knee Injury and Osteoarthritis Outcome (KOOS) scores. Bilateral stress radiographs were performed. The degree of osteoarthritis was assessed using Kellgren Lawrence score. Pearson correlations of predictive factors for worse outcome were performed (p < 0.05). RESULTS: Categorically, total IKDC 2000 was B (nearly normal) in five (31%), C (abnormal) in seven (44%) and D (severely abnormal) in four (25%) patients. Lysholm score was 68 ± 22; KOOS symptom score was 40 ± 13, KOOS pain 26 ± 24, KOOS activity 18 ± 18, KOOS sport 51 ± 32 and KOOS LQ 44 ± 26. Median Tegner score decreased from pre-injury 7 (range 4-10) to 4 (range 2-10) at follow-up. Kellgren Lawrence score showed minimal osteoarthritis in seven (44%), moderate osteoarthritis in seven (44%) and severe osteoarthritis in one (12%) patient. CONCLUSIONS: The challenging group of patients treated by PCL reconstruction and popliteus bypass according to Mueller et al. or popliteus refixation showed only moderate clinical and radiological long-term outcome without statistical difference, even if patient age at surgery and the long-term follow-up is acknowledged. Anatomical posterolateral corner reconstruction techniques should be preferred.

Fibrous cartilage of human menisci is less shock-absorbing and energy-dissipating than hyaline cartilage.

PURPOSE: To test meniscal mechanical properties such as the dynamic modulus of elasticity E* and the loss angle δ at two loading frequencies ω at different locations of the menisci and compare it to E* and δ of hyaline cartilage in indentation mode with spherical indenters. METHODS: On nine pairs of human menisci, the dynamic E*-modulus and loss angle δ (as a measure of the energy dissipation) were determined. The measurements were performed at two different strain rates (slow sinusoidal and fast single impact) to show the strain rate dependence of the material. The measurements were compared to previous similar measurements with the same equipment on human hyaline cartilage. RESULTS: The resultant E* at fast indentation (median 1.16 MPa) was significantly higher, and the loss angle was significantly lower (median 10.2°) compared to slow-loading mode's E* and δ (median 0.18 MPa and 16.9°, respectively). Further, significant differences for different locations are shown. On the medial meniscus, the anterior horn shows the highest resultant dynamic modulus. CONCLUSION: In dynamic measurements with a spherical indenter, the menisci are much softer and less energy-dissipating than hyaline cartilage. Further, the menisci are stiffer and less energy-dissipating in the middle, intermediate part compared to the meniscal base. In compression, the energy dissipation of meniscus cartilage plays a minor role compared to hyaline cartilage. At high impacts, energy dissipation is less than on low impacts, similar to cartilage.

Assessment of in vivo loading history of the patellofemoral joint: a study combining patellar position, tilt, alignment and bone SPECT/CT.

PURPOSE: The current study investigates whether patella height and tilt or leg alignment influence the intensity values as well as the distribution pattern of single photon emission computerized tomography/computerized tomography (SPECT/CT) tracer uptake in the patellofemoral joint. METHODS: 99mTc-HDP-SPECT/CT and radiographs of consecutive 84 knees were prospectively obtained. Lateral radiographs were analyzed in terms of patellar height, Insall-Salvati index and modified Insall-Salvati index. Skyline views were analyzed for Laurin's lateral patellofemoral angle. On long-leg radiographs, the mechanical leg alignment was classified as varus, valgus or neutral. SPECT/CT was analyzed for each anatomical region using a previously validated SPECT/CT localization and grading algorithm. Mean, standard deviation, minimum and maximum of grading for each area of the localization scheme were recorded. Nonparametric Spearman's correlations were used to correlate patellar height, lateral patellar angle and leg alignment with the tracer uptake intensity. Chi-square statistics were used for categorical data (p < 0.05). RESULTS: A patella baja correlated significantly with higher SPECT/CT tracer uptake in all patellar and lateral femoral regions (p < 0.001). A higher lateral patellar tilt correlated significantly with higher tracer uptake in the superior lateral femoral parts and the tibial tubercle. In mechanically varus aligned knees, there was significantly higher SPECT/CT tracer uptake on the medial and in valgus knees on the lateral part of the patellofemoral joint (p < 0.05). CONCLUSIONS: As the intensity and distribution of the SPECT/CT significantly correlated with patella baja and patellar tilt, SPECT/CT might be considered as imaging modality for evaluating patients with patellofemoral disorders and for follow-up of patients after patellofemoral realignment procedures. LEVEL OF EVIDENCE: Diagnostic study, Level II.

Heel-strike in walking: assessment of potential sources of intra- and inter-subject variability in the activation patterns of muscles stabilizing the knee joint.

The electromyographic (EMG) signal is known to show large intra-subject and inter-subject variability. Adaptation to, and preparation for, the heel-strike event have been hypothesized to be major sources of EMG variability in walking. The aim of this study was to assess these hypotheses using a principal component analysis (PCA). Two waveform shapes with distinct characteristic features were proposed based on conceptual considerations of how the neuro-muscular system might prepare for, or adapt to, the heel-strike event. PCA waveforms obtained from knee muscle EMG signals were then compared with the predicted characteristic features of the two proposed waveforms. Surface EMG signals were recorded for ten healthy adult female subjects during level walking at a self-selected speed, for the following muscles; rectus femoris, vastus medialis, vastus lateralis, semitendinosus, and biceps femoris. For a period of 200 ms before and after heel-strike, EMG power was extracted using a wavelet transformation (19-395 Hz). The resultant EMG waveforms (18 per subject) were submitted to intra-subject and inter-subject PCA. In all analyzed muscles, the shapes of the first and second principal component (PC-) vectors agreed well with the predicted waveforms. These two PC-vectors accounted for 50-60% of the overall variability, in both inter-subject and intra-subject analyses. It was also found that the shape of the first PC-vector was consistent between subjects, while higher-order PC-vectors differed between subjects. These results support the hypothesis that adaptation to, and preparation for, a variable heel-strike event are both major sources of EMG variability in walking.

The unhappy total knee arthroplasty (TKA) patient: higher WOMAC and lower KSS in depressed patients prior and after TKA.

PURPOSE: Patient-based and psychological factors do influence outcome in patients undergoing total knee arthroplasty (TKA). The purpose was to investigate if preoperative psychological factors influence the subjective and objective outcomes 6 weeks, 4 months and 1 year after TKA. Our hypothesis was that there is a significant influence of psychological factors on clinical outcome scores before and after TKA. METHODS: A prospective, longitudinal, single-cohort study investigating the correlation of depression, control beliefs, anxiety and a variety of other psychological factors with outcomes of patients undergoing TKA was performed. A total of 104 consecutive patients were investigated preoperatively using the Beck`s depression inventory, the State-Trait Anxiety Index, the questionnaire for assessment of control beliefs and the SCL-90R inventory. The Knee Society Clinical Rating System (KSS) and the WOMAC were used. Analysis of TKA position was performed on radiographs according to Ewald et al. Correlation of psychological variables with outcomes was performed (p < .05). RESULTS: Self-efficacy did not influence clinical scores. More depressed patients showed higher pre- and postoperative WOMAC scores, but no difference in amelioration. KSS scores were not influenced. Patients with higher State and Trait Anxiety Indexes had higher WOMAC and lower KSS scores before and after the operation, but most significant correlations were <0.3. Several SCL-90 dimensions had significant correlations with pre- and postoperative clinical scores, but not with their amelioration. The SCL-90 subscore for somatization and the overall SCL-90 significantly correlated with the WOMAC, KSS before and after TKA. CONCLUSIONS: Depression, anxiety, a tendency to somatize and psychological distress were identified as significant predictors for poorer clinical outcomes before and/or after TKA. Standardized preoperative screening and subsequent treatment should become part of the preoperative work-up in orthopaedic practice. LEVEL OF EVIDENCE: Prognostic prospective, Level I.

From open to arthroscopic anatomical ACL-reconstructions: the long way round. A statement paper.

The single-incision anterior cruciate ligament (ACL) reconstruction evidently has its shortcomings. In an attempt to improve the biomechanical but also the biological state of the knees after an ACL-reconstruction, double, even triple-bundle reconstructions have been popularised recently. As a positive side effect, details concerning ACL-insertion anatomy were brought back into the focus. In our opinion it would be more straight forward and logical to replace the non-anatomical single-incision technique with a more anatomic single-bundle ACL-reconstruction technique.

Single photon emission computerized tomography and conventional computerized tomography (SPECT/CT) for evaluation of patients after anterior cruciate ligament reconstruction: a novel standardized algorithm combining mechanical and metabolic information.

PURPOSE: The purpose of this study was to introduce a novel standardized algorithm using SPECT/CT, which promises the potential combined assessment of the biology of the joint in particular the bone-graft-fixation complex and the 3D tunnel placement in patients after ACL reconstruction. Its clinical application and inter- and intra-observer reliability should be critically evaluated. METHODS: A novel SPECT/CT localization scheme consisting of 13 tibial, 9 femoral and 4 patellar regions on standardized axial, coronal and sagittal slices is proposed. The tracer activity on SPECT/CT was localized and recorded in 25 consecutive patients using a 3D volumetric and quantitative analysis software. The inter- and intra-observer reliability was assessed for localization and tracer activity. The tunnel position was assessed in 3D-CT using standardized frames of reference. The inter- and intra-observer reliability (OR) of the measured distances were calculated (ICC). RESULTS: The localization scheme for tracer uptake analysis was useful and easily applicable in all 25 knees. It showed very high inter-OR and intra-ORs for all regions (ICC > 0.80). Tibial and femoral tunnel position measurements showed strong agreement between the readings of the two observers; the ICCs for the position, angulation, length and entry point of the femoral tunnel were >0.88 (intra-OR) and >0.86 (inter-OR). The ICC for the position of the tibial tunnel (angulation, length and entry point) was >0.79 (intra-OR) and >0.74 (inter-OR). CONCLUSIONS: The SPECT/CT algorithm presented is highly reliable and clinically feasible. Combining the 3D-mechanical information on tunnel placement and attachment areas and the 3D metabolic data will be helpful in evaluating patients with pain after ACL reconstruction.

Long-term results of arthroscopically assisted anatomical single-bundle anterior cruciate ligament reconstruction using patellar tendon autograft: are there any predictors for the development of osteoarthritis?

PURPOSE: The primary purpose of our study was to analyse the long-term outcome of patients treated for anterior cruciate ligament (ACL) tears by anatomical single-bundle ACL reconstruction with patellar tendon autograft. The secondary purpose was to identify predictive factors for good outcome and occurrence of osteoarthritis. METHODS: Sixty-three patients (m:f = 54:9; mean age at surgery, 27 ± 7 years) treated by ACL reconstruction were evaluated with a mean follow-up of 16 ± 1 years using IKDC2000, the SF36, Lysholm and Tegner score, Knee Society score, visual analogue scale for pain and satisfaction and KOOS. The femoral tunnel position was evaluated according to Sommer. It was also assessed in percentage of the Blumensaat line and the tibial tunnel position in percentage of the total anterior-posterior plateau length. The extent of osteoarthritis was graded according to the Kellgren-Lawrence score. RESULTS: The total IKDC2000 was normal in 20 (32 %), nearly normal in 29 (46 %), abnormal in 12 (19 %) and severely abnormal in 3 (5 %) of patients. The mean total SF-36 was 89 ± 13, the Lysholm score 95 ± 12, the Knee Society score 191 ± 16 and the total KOOS 84 ± 19. The Tegner score decreased from pre-injury 7(4-10) to 6 (2-10) at follow-up. The Kellgren-Lawrence score was normal in 17 (27 %), suspected osteoarthritis in 25 (40 %), minimal osteoarthritis in 5 (8 %), moderate osteoarthritis in 9 (14 %) and severe osteoarthritis in 3 patients (5 %). The femoral tunnel was in zone A in 43 patients (68 %), in zone B in 16 (25 %) and in zone C in 4 patients (7 %). The femoral tunnel position in percentage of the Blumensaat line was 49 ± 3 (range, 44-57), and the tibial tunnel position in percentage of the total anterior-posterior plateau length was 32 ± 6 (range, 21-46). Patients with meniscal lesion at the time of ACL tear showed significantly less favourable outcomes than those without. CONCLUSIONS: Patients treated by the proposed ACL reconstruction technique showed on average good to excellent long-term results. A meniscal lesion at the time of ACL tear was highly predictive for less favourable outcome.

Assessment of loading history of compartments in the knee using bone SPECT/CT: a study combining alignment and 99mTc-HDP tracer uptake/distribution patterns.

This study investigates if the mechanical/anatomical alignment influences the intensity values as well as the distribution pattern of SPECT/CT tracer uptake. Eighty-five knees (mean age 48 ± 16) undergoing 99mTc-HDP-SPECT/CT due to pain were prospectively included. SPECT/CTs were analyzed using a previously validated localization method. The maximum intensities in each femoral, tibial, and patellar joint compartment (medial, lateral, central, superior, and inferior) were noted using a color-coded grading scale (0-10). The Kellgren-Lawrence osteoarthritis score (KL) was assessed on standardized radiographs. Long leg radiographs were used to assess the mechanical/anatomical leg alignment, which was classified as varus, valgus, or neutral. The alignment and KL was correlated with the intensity of tracer uptake in each area of interest (p < 0.05). The intensity of SPECT/CT tracer uptake in the medial and lateral knee compartment significantly correlated with varus or valgus alignment of the knee. A higher degree of osteoarthritis was significantly related to higher tracer uptake in the corresponding joint compartments. SPECT/CT reflects the specific loading pattern of the knee with regard to its alignment. It is also related to the degree of osteoarthritis. Hence, SPECT/CT should be considered for follow-up of patients after realignment treatments, osteotomies, deloader devices, or insoles.

SPECT/CT tracer uptake is influenced by tunnel orientation and position of the femoral and tibial ACL graft insertion site.

PURPOSE: SPECT/CT is a hybrid imaging modality, which combines a 3D scintigraphy (SPECT) and a conventional computerised tomography (CT). SPECT/CT allows accurate anatomical localisation of metabolic tracer activity. It allows the correlation of surgical factors such as tunnel position and orientation with mechanical alignment, clinical outcome and biological factors. The purpose of this study was to investigate whether the SPECT/CT tracer uptake (intensity and distribution) correlates with the stability and laxity of the knee joint and the position and orientation of the tibial and femoral tunnels in patients after anterior cruciate ligament (ACL) reconstruction. METHODS: A consecutive series of knees (n=66), with symptoms of pain and/or instability after ACL reconstruction were prospectively evaluated using clinical examination and 99mTc-HDP-SPECT/CT. Clinical laxity testing was performed using the Rolimeter (Ormed, Freiburg, Germany) including Lachman testing (0-2 mm, 3-5 mm, 6-10 mm, >10 mm), anterior drawer test (0-2 mm, 3-5 mm, 6-10 mm, >10 mm), pivot shift test (positive versus negative) and patient-based subjective instability (yes versus no). For analysis of SPECT/CT tracer uptake a previously validated SPECT/CT localisation scheme consisting of 17 tibial, nine femoral and four patellar regions on standardised axial, coronal, and sagittal slices was used. The tracer activity on SPECT/CT was localised and recorded using a 3D volumetric and quantitative analysis software. Mean, standard deviation, minimum and maximum of grading for each area of the localisation scheme were recorded. The position and orientation of the tibial and femoral tunnel was assessed using a previously published method on 3D-CT. RESULTS: Correlation of instability, pivot shift as well as clinical laxity testing with 99mTc-HDP-SPECT/CT tracer uptake intensity and distribution showed no significant correlation. 99mTc-HDP-SPECT/CT tracer uptake correlated significantly with the position and orientation of the ACL graft. A more horizontal femoral graft position showed significantly increased tracer uptake within the superior and posterior femoral regions. A more posteriorly-placed femoral insertion site showed significantly more tracer uptake within the femoral and tibial tunnel regions. A more vertical or a less medial tibial tunnel orientation showed significant increased uptake within the tibial and femoral tunnel regions. A more anterior tibial tunnel position showed significantly more tracer uptake in the femoral and tibial tunnel regions as well as the entire tibiofemoral joint. CONCLUSIONS: SPECT/CT tracer uptake intensity and distribution showed a significant correlation with the femoral and tibial tunnel position and orientation in patients with symptomatic knees after ACL reconstruction. No correlation was found with stability or clinical laxity. SPECT/CT tracer uptake distribution has the potential to give us important information on joint homeostasis and remodelling after ACL reconstruction. It might help to predict ACL graft failure and improve our surgical ACL reconstruction technique in finding the optimal tunnel and graft position and orientation.

Limb shortening osteotomy in a patient with achondroplasia and leg length difference after total hip arthroplasty.

INTRODUCTION: Achondroplasia is the most common reason for disproportionate short stature. Normally, orthopedic limb lengthening procedures must be discussed in the course of this genetic disorder and have been successful in numerous achondroplastic patients in the past. In some cases, the disease may lead to leg length differences with need for surgical correction. CASE REPORT: We report a case of achondroplastic dysplastic coxarthrosis with symptomatic leg length difference after bilateral total hip arthroplasty in a 52-year-old female patient, in which a distal femoral shortening osteotomy was successfully performed. CONCLUSION: Femoral shortening osteotomy is very uncommon in patients with achondroplasia. We conclude, however, that in rare cases it can be indicated and provide the advantage of shorter operation time, less perioperative complications and faster recovery compared to leg lengthening procedures.

Anterolateral approach using tibial tubercle osteotomy for total knee arthroplasty: can we predict failure?

PURPOSE: The purpose of this study was to identify predictive factors for the occurrence of complications in a consecutive series of patients who underwent step-cut tibial tubercle osteotomy (TTO) and subsequent screw refixation in primary total knee arthroplasty (TKA). METHODS: Using standardised conventional radiographs, critical parameters including TTO length and depth, proximal abutment width (OT), and orientation and placement of fixation screws were measured in 422 patients (mean age of 71 years and a follow-up time range of one to five years) with two screw fixations. RESULTS: Medial spatial orientation in the distal screw (11 %, p=0.046), the TTO length (<55.4 mm, p=0.013), the OT width (<14 mm, p=0.002) and the distance of the distal refixation screw from the TKA (<51.7 mm, p=0.003) were significant factors for the occurrence of complications. CONCLUSIONS: Age, gender, comorbidities, height, weight and/or the body mass index had no significant influence on the occurrence of complications. The TTO-related complication rate was 3 %. Consideration of these key surgical factors leads to improved outcomes.