Friend or Foe? Biomechanics and Its Key Role in Paediatric Orthopaedics.

Biomechanics play a key role in the development, progression and treatment of musculoskeletal disease in children [...].

Effect of tranexamic acid on intraoperative blood loss in pediatric osteotomies around the hip: Study protocol for a double-blind randomized placebo-controlled trial.

Background: Proximal femoral and/or pelvic osteotomies (PFPOs) can be indicated for a multitude of hip pathologies in (often asymptomatic) children, to prevent future hip problems. These procedures can result in significant blood loss. Tranexamic acid (TXA) is an antifibrinolytic agent routinely administered in adult trauma and joint reconstruction surgery to reduce blood loss. TXA is also registered for use in children and reported safe and beneficial for pediatric trauma, cardiac, and spinal surgery. However, for pediatric orthopedics, particularly for PFPOs, the available evidence is limited. Therefore, the current trial will investigate the potential reducing effect of preoperative TXA on intraoperative blood loss in pediatric PFPOs. Methods: In this single-center, double-blind, randomized placebo-controlled trial, we aim to include 180 participants aged from 1 to 18 years undergoing PFPOs for any indication at our institution. Participants will be randomized to receive either TXA or placebo (saline) during anesthetic induction. The primary outcome is intraoperative estimated blood loss (mL/kg), which is determined gravimetrically. Secondary outcomes include the percentage of patients with excessive blood loss (>20 mL/kg), procedure time and hospital stay, and postoperative hemoglobin level changes. Discussion: This will be the first prospective study investigating the effect of preoperative TXA on intraoperative blood loss in pediatric PFPOs. Its results will help to determine whether it would be advisable to adopt preoperative TXA as a standard medication to minimize blood loss and prevent complications in this vulnerable population. Trial registration: EudraCT: 2022-002384-30. Prospectively registered on September 26, 2022.

Strategies to optimize the information provision for parents of children with developmental dysplasia of the hip.

Aims: The aim of this study was to identify the information topics that should be addressed according to the parents of children with developmental dysplasia of the hip (DDH) in the diagnostic and treatment phase during the first year of life. Second, we explored parental recommendations to further optimize the information provision in DDH care. Methods: A qualitative study with semi-structured interviews was conducted between September and December 2020. A purposive sample of parents of children aged younger than one year, who were treated for DDH with a Pavlik harness, were interviewed until data saturation was achieved. A total of 20 interviews with 22 parents were conducted. Interviews were audio recorded, transcribed verbatim, independently reviewed, and coded into categories and themes. Results: Interviews revealed four fundamental information topics that should be addressed in the different phases of the DDH healthcare trajectory: general information (screening phase), patient-specific information (diagnostic and treatment phase), practical information (treatment phase), and future perspectives (treatment and follow-up phase). To further optimize the information provision in DDH care, parents wished for more accessible and trustworthy general information prior to the first hospital visit to be better prepared for the diagnosis. Furthermore, parents wanted more personalized and visually supported information for a better understanding of the nature of the disease and the reason for treatment. Conclusion: This study offers novel insights to optimize the information provision in DDH care. The main finding is the shift in information need from general information in the screening phase to patient-specific information in the diagnostic and treatment phase of DDH. Parents prefer visually-supported information, provided in a timely fashion, and tailored to their child's situation. These recommendations potentially decrease parental anxiety, insecurity, confusion, and increase parental empowerment and treatment adherence throughout the diagnostic and treatment phase of DDH.

The Importance of Monitoring and Factors That May Influence Leg Length Difference in Developmental Dysplasia of the Hip.

In unilateral Developmental Dysplasia of the Hip (DDH), avascular necrosis (AVN), femoral or pelvic osteotomy, and residual dysplasia causing subluxation of the proximal femur may influence Leg Length Discrepancy (LLD). This can lead to gait compensation, pelvic obliquity, and spinal curvature. The aim of this study is to determine the prevalence of LLD, establish which limb segment contributes to the discrepancy, describe how AVN influences LLD, and ascertain variables that may influence the need for LLD corrective procedures. METHODOLOGY: This study assessed long-leg radiographs at skeletal maturity. Radiographs were assessed for the articulo-trochanteric distance (ATD) and femoral and tibial length. AVN was classified according to Kalamchi-MacEwen. RESULTS: 109 patients were included. The affected/DDH leg was longer in 72/109 (66%) patients. The length difference was mainly in the subtrochanteric segment of the femur. AVN negatively influenced leg length. Older (≥three years) patients with multiple procedures were more likely to have AVN. LLD interventions were performed in 30 (27.5%) patients. AVN grade or type of DDH surgery did not influence the odds of needing a procedure to correct LLD. CONCLUSIONS: Procedures to correct LLD were performed irrespective of previous DDH surgery or AVN grades. In most patients, the affected/DDH leg was longer, mainly in the subtrochanteric segment of the femur, largely influenced by femoral osteotomy in patients with multiple operative procedures for DDH. We recommend careful monitoring of LLD in DDH.

Tension-band Plating for Leg-length Discrepancy Correction.

Aim: Dual tension-band plates are used for temporary epiphysiodesis and longitudinal guided growth. The study aim was to assess rate of correction, to identify development of femoral and tibial intra-articular deformity during correction and to document resumption of growth after plate removal. Materials and methods: A retrospective study of 34 consecutive patients treated with dual tension-band plates between 2012 and 2020 was performed. Twenty-four patients had surgery at the distal femur, six at the proximal tibia and four at both. Twenty-five female patients were treated at a mean age of 11.6 (±1.4) years and nine male patients at 13.5 (±1.5) years. Measurements were performed on standardised long-leg radiographs and included leg-length discrepancy (LLD), joint line congruency angle (JLCA), tibial roof angle, femoral floor angle and notch-intercondylar distance. Measurements were taken pre-operatively, at the end of discrepancy correction and at skeletal maturity. Results: The LLD reduced by a mean of 12.9 mm (95% CI 10.2-15.5) with the mean residual difference 8.4 mm (95% CI 5.4-11.4). The mean correction rate for the proximal tibia was 0.40 (SD 0.33) mm/month and 0.68 (SD 0.36) mm/month for the distal femur. A significant mean change in residual LLD [-2.5 mm (95% CI -4.2 to -0.7)] was observed between plate removal and skeletal maturity at the femoral level only. After length discrepancy correction, the tibial roof angle showed a significant difference of 8.4° (95% CI 13.4-3.4) between legs. In femoral epiphysiodesis patients, no important differences were observed. Conclusion: A significant reduction in LLD can be achieved using dual tension-band plating. A change in intra-articular morphology was observed only in the proximal tibia and not in the distal femur. In the authors' opinion, tension-band plating is a useful tool for leg-length equalisation but should be reserved for younger patients or when residual growth is difficult to predict. It is one of the management strategies for limb-length difference prior to skeletal maturity. How to cite this article: Tolk JJ, Merchant R, Calder PR, et al. Tension-band Plating for Leg-length Discrepancy Correction. Strategies Trauma Limb Reconstr 2022;17(1):19-25.

Leg length discrepancy in patients with Perthes' disease : a note of caution for the arthroplasty surgeon.

AIMS: Perthes' disease (PD) often results in femoral head deformity and leg length discrepancy (LLD). Our objective was to analyze femoral morphology in PD patients at skeletal maturity to assess where the LLD originates, and evaluate the effect of contralateral epiphysiodesis for length equalization on proximal and subtrochanteric femoral lengths. METHODS: All patients treated for PD in our institution between January 2013 and June 2020 were reviewed retrospectively. Patients with unilateral PD, LLD of ≥ 5 mm, and long-leg standing radiographs at skeletal maturity were included. Total leg length, femoral and tibial length, articulotrochanteric distance (ATD), and subtrochanteric femoral length were compared between PD side and the unaffected side. Furthermore, we compared leg length measurements between patients who did and who did not have a contralateral epiphysiodesis. RESULTS: Overall, 79 patients were included, of whom 21 underwent contralateral epiphysiodesis for leg length correction. In the complete cohort, the mean LLD was 1.8 cm (95% confidence interval (CI) 1.5 to 2.0), mean ATD difference was 1.8 cm (95% CI -2.1 to -1.9), and mean subtrochanteric difference was -0.2 cm (95% CI -0.4 to 0.1). In the epiphysiodesis group, the mean LLD before epiphysiodesis was 2.7 cm (95% CI 1.3 to 3.4) and 1.3 cm (95% CI -0.5 to 3.8) at skeletal maturity. In the nonepiphysiodesis group the mean LLD was 2.0 cm (95% CI 0.5 to 5.1; p = 0.016). The subtrochanteric region on the PD side was significantly longer at skeletal maturity in the epiphysiodesis group compared to the nonepiphysiodesis group (-1.0 cm (95% CI -2.4 to 0.6) vs 0.1 cm (95% CI -1.0 to 2.1); p < 0.001). CONCLUSION: This study demonstrates that LLD after PD originates from the proximal segment only. In patients who had contralateral epiphysiodesis to balance leg length, this is achieved by creating a difference in subtrochanteric length. Arthroplasty surgeons need to be aware that shortening of the proximal femur segment in PD patients may be misleading, as the ipsilateral subtrochanteric length in these patients can be longer. Therefore, we strongly advise long-leg standing films for THA planning in PD patients in order to avoid inadvertently lengthening the limb. Cite this article: Bone Joint J 2021;103-B(11):1736-1741.

The influence of expectation modification in knee arthroplasty on satisfaction of patients: a randomized controlled trial.

AIMS: Meeting preoperative expectations is known to be of major influence on postoperative satisfaction after total knee arthroplasty (TKA). Improved management of expectation, resulting in more realistic expectations can potentially lead to higher postoperative satisfaction. The objective of this study was to assess the effect of an additional preoperative education module, addressing realistic expectations for long-term functional recovery, on postoperative satisfaction and expectation fulfilment. METHODS: In total, 204 primary TKA patients with osteoarthritis were enrolled in this randomized controlled trial (RCT). Patients were allocated to either usual preoperative education (control group) or usual education plus an additional module on realistic expectations (intervention group). Primary outcome was being very satisfied (numerical rating scale for satisfaction ≥ 8) with the treatment result at 12 months' follow-up. Other outcomes were change in preoperative expectations and postoperative expectation fulfilment. RESULTS: A total of 187 patients (91.7%) were available for analysis at follow-up. In the intention-to-treat analysis, 58.5% (55/94) of patients were very satisfied with the treatment result in the control group, and 69.9% (65/93) of patients in the intervention group (adjusted odds ratio (AOR) 1.72, 95% confidence interval (CI) 0.90 to 3.29). A per-protocol analysis for patients who attended the education session (92.0%, n = 172) showed that 56.9% (49/86) of patients were very satisfied in the control group and 74.4% (61/86) in the intervention group (AOR 2.44, 95% CI 1.21 to 4.91). After preoperative education, the expectation scores in the intervention group were significantly lower (mean difference -6.9 (95% CI -10.2 to -3.6)) and did not alter in the control group (mean difference 0.5 (95% CI -2.9 to 3.9)). Overall, fulfilment of expectations at 12 months was significantly higher in the intervention group (mean difference 11.4% (95% CI 2.3 to 20.5)). CONCLUSION: Improved preoperative patient education can modify patient expectations, resulting in higher postoperative fulfilment of expectation and higher satisfaction in the group that attended the preoperative education. This is the first RCT to confirm the potential of improved expectation management on satisfaction after TKA. Cite this article: Bone Joint J 2021;103-B(4):619-626.

Timing of Repeat Ultrasound Examination in Treatment of Stable Developmental Dysplasia of the Hip.

BACKGROUND: Worldwide a wide variation exists in duration of Pavlik harness treatment for infants up to 6 months with stable developmental dysplasia of the hip (DDH). The purpose of this study was to evaluate whether shortening the time to first routine follow-up ultrasound after initiation of Pavlik harness treatment would reduce treatment duration and whether this influenced radiologic outcome at 1 year of age. Furthermore, predictors of higher acetabular index (AI) at 1 year of age were investigated. METHODS: A retrospective study was conducted in infants with stable DDH (Graf IIb and IIc) diagnosed and treated between 2015 and 2017. Two groups were identified: first routine follow-up ultrasound at 12 weeks after Pavlik harness initiation (group I) and first routine follow-up ultrasound at 6 weeks after Pavlik harness initiation (group II). In both groups, treatment was continued until repeat ultrasound measurements (every 6 wk) showed a normalized hip. Radiologic outcome at 1 year of age was defined as residual dysplasia measured on an anteroposterior hip radiograph according to the Tönnis table. RESULTS: A total of 222 infants were included. The median time of Pavlik harness treatment was 12 weeks (interquartile range, 11.9 to 12.3) in group I compared with 6.1 weeks (interquartile range, 6.0 to 7.5) in group II (P<0.001). Residual dysplasia at 1 year of age was detected in 20 infants (16.8%) in group I compared with 11 infants (10.7%) in group II (P=0.189). The multivariable prediction model showed that positive family history and lower baseline alpha angle correlate with a higher AI at 1 year of age. CONCLUSIONS: First routine follow-up ultrasound can be safely brought forward from 12 to 6 weeks after Pavlik harness initiation. Furthermore, infants with a positive family history for DDH and an initial low alpha angle are at higher risk to have a higher AI at 1 year of age. LEVEL OF EVIDENCE: Level III-retrospective study.

The Development of Leg Length Difference and Influence on Persistent Dysplasia in Patients with Developmental Dysplasia of the Hip.

INTRODUCTION: Leg-length difference (LLD) is common in patients with developmental dysplasia of the hip (DDH). LLD of > 1 cm at skeletal maturity is reported in > 40% of patients, with the majority related to ipsilateral overgrowth. A longer DDH leg might lead to excessive mechanical loading at the acetabular margin, resulting in compromised acetabular development. We hypothesised that the LLD would negatively influence acetabular development. If so, it would be advantageous to identify such patients early in the course of follow-up, and address this if necessary. METHODS: A retrospective study was conducted on a consecutive series of DDH patients managed surgically at the Royal National Orthopaedic Hospital, Stanmore, United Kingdom. We included patients with adequate long-leg radiographs at the age of 4-8 years (early-FU) and skeletal maturity (final-FU). Bilateral cases and those who underwent surgical procedures for hip dysplasia during the follow-up period were excluded. Measurements including leg length and centre-edge-angle (CE-angle) were obtained at the 2 time points. RESULTS: Twenty-seven patients were included, mean age at early-FU 5.7 (± 0.9) years, and 13.9 (± 1.0) years at final-FU. Mean LLD at early-FU was 9.5 (± 7.6) mm and 10.9 (± 9.4) mm at final-FU, p = 0.337. Correlation between early- and final-FU LLD was 0.68 (p < 0.001). The mean CE-angle at early follow-up was 14.6° (± 9.8), this improved to 23.2° (± 8.2) at skeletal maturity (p = 0.003, paired samples t-test). Linear regression analysis showed a non-significant trend towards less CE-angle improvement in patients with more initial residual dysplasia and more initial LLD. CONCLUSION: Most leg-length differences can be identified early in the follow-up period, nevertheless, considerable individual changes in LLD are observed on continued follow-up. Furthermore, a trend was observed towards impaired acetabular improvement in patients with more LLD. These findings justify careful clinical and radiological monitoring of LLD from an early stage in the follow-up period. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s43465-021-00492-5.

[Touched by an angel]. / Een jongen met afwijkende pinken.

The case of a 4-year-old boy with a symmetrical deformity of the 5th fingers is presented. Radiographs showed dysplastic development of the middle phalanx resembling the shape of ''Christmas tree angels''. A finding typical for Angel-shaped phalango-epiphyseal dysplasia (ASPED). Differential diagnosis, associated conditions and treatment are discussed.

Outcome Expectations of Total Knee Arthroplasty Patients: The Influence of Demographic Factors, Pain, Personality Traits, Physical and Psychological Status.

Unfulfilled preoperative expectations have a strong influence on the outcome after total knee arthroplasty (TKA). More insight into determinants of the level of expectations is useful in identifying patients at risk for having expectations of the treatment result that are too high or too low. This information can be used in optimizing preoperative expectation management. The aim of the current study was to analyze to what extent preoperative outcome expectations of TKA patients are affected by psychological factors, demographic factors, pain, physical function, and general health status. We performed a cross-sectional analysis of 204 patients with symptomatic and radiographic knee osteoarthritis (OA), scheduled for primary TKA. Outcome expectations were measured using the hospital for special surgery knee replacement expectations survey. Independent variables included were age, sex, body mass index, and patient-reported outcome measures for pain, physical function, quality of life, anxiety, depression, catastrophizing, optimism, and pessimism. Multiple linear regression analyses were used to evaluate associations between these variables and preoperative outcome expectations. Female sex, higher age, higher depression score, and duration of complaints > 50 months showed to be significant predictors of lower expectations for the treatment outcome after TKA. Baseline pain and function scores were not related to the level of preoperative expectations. The present study aids in identifying patients at risk for having either too high or too low expectations. This knowledge can be utilized in individualized expectation management interventions.

Development of Preoperative Prediction Models for Pain and Functional Outcome After Total Knee Arthroplasty Using The Dutch Arthroplasty Register Data.

BACKGROUND: One of the main determinants of treatment satisfaction after total knee arthroplasty (TKA) is the fulfillment of preoperative expectations. For optimal expectation management, it is useful to accurately predict the treatment result. Multiple patient factors registered in the Dutch Arthroplasty Register (LROI) can potentially be utilized to estimate the most likely treatment result. The aim of the present study is to create and validate models that predict residual symptoms for patients undergoing primary TKA for knee osteoarthritis. METHODS: Data were extracted from the LROI of all TKA patients who had preoperative and postoperative patient-reported outcome measures registered. Multivariable logistic regression analyses were performed to construct predictive algorithms for satisfaction, treatment success, and residual symptoms concerning pain at rest and during activity, sit-to-stand movement, stair negotiation, walking, performance of activities of daily living, kneeling, and squatting. We assessed predictive performance by examining measures of calibration and discrimination. RESULTS: Data of 7071 patients could be included for data analysis. Residual complaints on kneeling (female 72%/male 59%) and squatting (female 71%/male 56%) were reported most frequently, and least residual complaints were scored for walking (female 16%/male 12%) and pain at rest (female 18%/male 14%). The predictive algorithms were presented as clinical calculators that present the probability of residual symptoms for an individual patient. The models for residual symptoms concerning sit-to-stand movement, stair negotiation, walking, activities of daily living, and treatment success showed acceptable discriminative values (area under the curve 0.68-0.74). The algorithms for residual complaints regarding kneeling, squatting, pain, and satisfaction showed less favorable results (area under the curve 0.58-0.64). The calibration curves showed adequate calibration for most of the models. CONCLUSION: A considerable proportion of patients have residual complaints after TKA. The present study showed that demographic and patient-reported outcome measure data collected in the LROI can be used to predict the probability of residual symptoms after TKA. The models developed in the present study predict the chance of residual symptoms for an individual patient on 10 specific items concerning treatment success, functional outcome, and pain relief. This prediction can be useful for individualized expectation management in patients planned for TKA.

Measurement properties of the OARSI core set of performance-based measures for hip osteoarthritis: a prospective cohort study on reliability, construct validity and responsiveness in 90 hip osteo-arthritis patients.

Background and purpose - Improvement of physical function is one of the main treatment goals in severe hip osteoarthritis (OA) patients. The Osteoarthritis Research Society International (OARSI) has identified a core set of performance-based tests to assess the construct physical function: 30-s chair stand test (30-s CST), 4x10-meter fast-paced walk test (40 m FPWT), and a stair-climb test. Despite this recommendation, available evidence on the measurement properties is limited. We evaluated the reliability, validity, and responsiveness of these performance-based measures in patients with hip OA scheduled for total hip arthroplasty (THA). Patients and methods - Baseline and 12-month follow-up measurements were prospectively obtained in 90 end-stage hip OA patients who underwent THA. As there is no gold standard for comparison, the hypothesis testing method was used for construct validity and responsiveness analysis. A test can be assumed valid if ≥75% of predefined hypotheses are confirmed. A subgroup (n = 30) underwent test-retest measurements for reliability analysis. The Oxford Hip Score, Hip injury and Osteoarthritis Outcome Score-Physical Function Short Form, pain during activity score, and muscle strength were used as comparator instruments. Results - Test-retest reliability was appropriate; intraclass correlation coefficient values exceeded 0.70 for all 3 tests. None of the performance-based measures reached 75% hypothesis confirmation for the construct validity or responsiveness analysis. Interpretation - The performance-based tests have good reliability in the assessment of physical function. Construct validity and responsiveness, using patient-reported measures and muscle strength as comparator instruments, could not be confirmed. Therefore, our findings do not justify their use for clinical practice.

The EKSPECT study: the influence of Expectation modification in Knee arthroplasty on Satisfaction of PatiEnts: study protocol for a randomized Controlled Trial.

BACKGROUND: One out of five patients is unsatisfied to some extent after total knee arthroplasty (TKA). Unmet expectations are the main driver of post-operative dissatisfaction. Improved pre-operative education on realistic expectations for long-term outcome after TKA potentially leads to higher post-operative satisfaction. The effect of expectation modification on post-operative satisfaction in TKA patients has not yet been studied. The primary objective of the presented study is to examine whether an educational module on long-term recovery after TKA will improve patient satisfaction compared to usual pre-operative education. METHODS: The EKSPECT study is a randomized controlled trial. Patients with symptomatic and radiographic knee osteoarthritis who are indicated for a primary TKA will be randomized to the usual pre-operative education (control group) or usual education plus an additional module on realistic expectations for long-term recovery (intervention group). Patients will be naïve to study objective and difference between study groups. Outcome expectations will be measured blinded for group allocation using the HSS Knee Replacement Expectations Survey at baseline (before the intervention), pre-operatively (after the intervention) and fulfillment of expectations at 12-month follow-up. Baseline physical function, quality of life and psychological factors are measured using self-reported questionnaires. The primary outcome measure is satisfaction with treatment result at the 12-month follow-up. DISCUSSION: The EKSPECT study should provide evidence on the effectiveness of an education module on long-term recovery after TKA to improve treatment satisfaction. If beneficial, the education module is a simple intervention with a low burden for patients, which can easily be implemented in clinical practice. TRIAL REGISTRATION: Dutch Trial Registry registration number: NTR5779 . Registered on 17 March 2016.

Total Knee Arthroplasty: What to Expect? A Survey of the Members of the Dutch Knee Society on Long-Term Recovery after Total Knee Arthroplasty.

The rate of satisfaction after total knee arthroplasty (TKA) is consistently reported around 80%, leaving one in five patients unsatisfied to some extent. Fulfillment of expectations is reported as the strongest predictor of treatment satisfaction. In this study, we aimed to evaluate what Dutch orthopedic surgeons assume are realistic expectations for recovery 1 year after TKA. We invited the members of the Dutch Knee Society (DKS) to fill out a web-based questionnaire. For expectation measurement, the validated Dutch version of the Hospital for Special Surgery (HSS) knee replacement expectations survey was used. A total of 150 invitations were successfully sent; 84 orthopedic surgeons responded (56%). The overall HSS knee replacement expectation score was 66.0 (standard deviation, 14.0) on a 0 to 100 scale. Most improvement was predicted for the items "pain relief" and "walking short distances." Expectations related to patients' ability to kneel or squat after TKA were scored poorly. To the opinion of the members of the DKS, after TKA improvement can be expected in domains of pain, function, activities, and psychological wellbeing. Return to normal is not likely to occur, especially in demanding physical activities.

Infection after anterior spinal fusion for idiopathic scoliosis using the Cotrel-Dubousset-Hopf system: A clinical case series of three patients.

BACKGROUND: Three patients with late-onset infection after multilevel instrumented anterior spinal fusion for idiopathic scoliosis, using the Cotrel-Dubousset-Hopf (CDH) system, are presented. The CDH-system is an anterior instrumentation with high biomechanical stability and rigidity, ensuring a stable primary fixation. Unlike after posterior spinal fusion, infection after anterior spinal fusion (ASF) for idiopathic scoliosis has rarely been reported. METHODS: The files of three patients who developed an infection after ASF for scoliosis using the CDH-system, were reviewed. The clinical presentation and diagnostic and therapeutic options are discussed. RESULTS: All three patients had a late-onset infection of the CDH-system, which was difficult to diagnose because of nonspecific symptoms. Radiographs and technetium bone scan appeared to be of low value. When an abscess was present, this could accurately be diagnosed with MRI or CT imaging. Operative treatment with implant removal and antibiotic therapy was successful in all cases. CONCLUSION: Late onset infections after ASF using the CDH-system presented with few and nonspecific symptoms. The clinical presentation was mainly characterized by vague abdominal- or back-pain after an interval of normal postoperative recovery, moderately raised infection parameters and inconclusive findings with imaging modalities. As treatment, implant removal, debridement and parenteral antibiotics are recommended. It should be noted though that implant removal poses serious risks for vascular and visceral structures.

Computer navigated versus conventional total knee arthroplasty.

In total knee arthroplasty (TKA), reconstruction of a neutral mechanical axis is of great importance. The main goal of this study was to compare the accuracy of alignment after conventional versus computer-assisted TKA. Additionally, the effect of computer-assisted surgery (CAS) on functional outcome was analyzed. Out of a consecutive series, 50 conventional TKA were compared with 50 computer-assisted TKA. Except for the use of CAS, all perioperative and postoperative interventions were comparable. Radiological outcome was analyzed on standardized standing long-leg radiographs. Functional outcome was assessed using the Oxford Knee Score (OKS) and the Knee Society Score (KSS). No significant difference in mean mechanical axis alignment between the two groups was found. The number of outliers deviating more than 3 degrees from the mechanical axis was significantly reduced by using CAS, with 50% outliers in the conventional group and 26% outliers in the CAS group (p = 0.023). At midterm follow-up, the OKS and KSS knee and function scores did not show statistical difference between the two groups. The present study showed a reduction of the number of outliers exceeding 3 degrees from the tibiofemoral mechanical axis using CAS-TKA. This improvement in accuracy did not result in improvement of the functional outcome at mid-term follow-up.