The Effects of Lower Extremity Rotational Malalignment on Pediatric Patient-reported Outcomes Measurement and Information System (PROMIS) Scores.

BACKGROUND: There is sparse literature demonstrating the relationship between lower limb pediatric idiopathic rotational malalignment (IRM) and patient-reported outcomes measurement information system (PROMIS) scores. Our goal is to determine and quantify the amount that IRM deformities, as measured with the 3D gait analysis, affect childrens' pain interference, mobility, and peer relationship PROMIS domains. Secondary outcomes include investigating the potential relationships between IRM and various subgroups (Pediatric Outcomes Data Collection Instrument (PODCI), gender, Body Mass Index (BMI), femur Versus tibia). We also examine whether the PROMIS domains correlate with PODCI in this population. METHODS: This study was a retrospective cohort, single institution, and consecutively recruited cases series. We identified 47 children over a 3-year period who were evaluated at the motion analysis center at our tertiary care hospital, with increased torsion of the femur or tibia. After exclusions, 25 children with IRM, documented PROMIS data and gait analysis were considered. RESULTS: Femoral malrotation had a significant relationship with female gender ( P =0.001) and increased BMI ( P <0.001). Femoral malrotation had a correlation with PROMIS pain interference ( P =0.016), whereas tibial rotation did not achieve significance ( P =0.084). In the ANOVA regression analysis, there was a strong prediction of the PROMIS mobility domain when both malrotation and pain interference were present ( P =0.007). There were Pearson Correlations of PROMIS and PODCI domains for Mobility Versus Sports ( P =0.007) and Pain Interference Versus Comfort/Pain ( P =0.004), respectively. CONCLUSION: The evident relationship between lower limb rotational malalignment and PROMIS scores signifies the likelihood for gait and pain disturbance. This in turn could show us that children are likely to be more debilitated and thus may benefit from timely correction. We aim to conduct this as a multicentre trial to confirm our findings. LEVEL OF EVIDENCE: Level IV.

Accuracy of computer navigation in total knee arthroplasty: A prospective computed tomography-based study.

INTRODUCTION: Evidence now exists advocating the use of computer navigation in total knee arthroplasty (TKA). Despite the introduction of new navigation systems into clinical practice no evidence currently exists showing independent verification of their accuracy. The aim of this study was to validate the in vivo accuracy of the Exactech Guided Personalised Surgery (GPS) computer navigation system using a validated computed tomography (CT) measurement of alignment. METHOD: Consecutive patients who underwent TKA using the GPS Navigation System at our institution were prospectively recruited. Intraoperative parameters of 3D alignment as measured by the GPS navigation system were recorded and compared against the postoperative measurements of alignment measured using the Perth CT Protocol to assess the accuracy of the GPS navigation system. RESULTS: 29 consecutive patients (13 male, 16 female) who underwent TKA were prospectively recruited. Overall, for all measures of 3D alignment the mean difference between intraoperatively recorded and postoperative CT-measured alignment was 1.55° ± 0.22° (95% confidence interval). Individual measurement differences in the femoral prosthesis were: coronal alignment 1.64° ± 0.52°; flexion 2.07° ± 0.55°; rotation 1.38° ± 0.33° Differences in the tibial prosthesis were: coronal alignment 2.03° ± 0.53°; slope 1.14° ± 0.39° The whole limb coronal alignment difference was 2.34° ± 0.83° CONCLUSION: The Exactech GPS Navigation system is very accurate with a high concordance between intraoperative and postoperative measures of alignment and prosthesis positioning. We therefore confidently validate the system and support its continued use in clinical practice. Other navigation systems should undergo a similar validation process.

How should new orthopaedic implants be introduced: an example and recommendations for best practice.

Continued advancements in orthopaedics have led to the development of many new implants; many of these are being utilized in clinical practice with little or no evidence base for their safety or effectiveness. Highly publicized failures in orthopaedic technology have led to an increased awareness of this issue in both medical and non-medical circles. In most cases, the significant harm caused to the public could have been avoided by the appropriately staged implementation of new implants. This review comments on the current literature regarding the optimal practice for the introduction of new orthopaedic technology. The authors' experience with the failed ESKA Adapter Short-stem/Modular Hip is described; the methodology used for its evaluation is used as a basis to discuss what was successful about the process and also give warning on what could be improved upon. The ideal practice requires new orthopaedic implants to be evaluated by high-volume surgeons in specialist orthopaedic hospitals. These studies should include biomechanical studies, radiostereophotometric analysis, implant retrieval and outcome assessment. Results and complications should be reported early to the appropriate joint registry and regulatory body. Once a suitable evidence base has developed, the implant can be distributed into wider clinical practice or withdrawn. These recommendations aim to protect the patient and public from harm while allowing surgical innovation to still continue.

A cadaver study validating CT assessment of acetabular component orientation: the Perth CT hip protocol.

OBJECTIVE: The aim was to develop a CT-based protocol to accurately measure post-operative acetabular cup inclination and anteversion establishing which bony reference points facilitate the most accurate estimation of these variables. MATERIALS AND METHODS: An all-polyethylene acetabular liner was implanted into a cadaveric acetabulum. A conventional pelvic CT scan was performed and reformatted images created in both functional and anterior pelvic planes. CT images were transferred to a Freedom-Plus Graphics software package enabling an identical, virtual 3D model of the cadaveric pelvis to be created and definitive acetabular cup orientation established. Using coronal and axial slices of the CT scans, acetabular cup inclination and anteversion were measured on five occasions by ten radiographers using differing predetermined bony landmarks as reference points. The intra- and inter-observer variation in measurement of acetabular cup orientation using varying bony reference points was assessed in comparison to the elucidated definitive cup position. RESULTS AND CONCLUSION: Virtually derived definitive acetabular cup orientation was measured showing cup inclination and anteversion as 41.0 and 22.5° respectively. Mean CT-based measurement of cup inclination and anteversion by ten radiographers were 43.1 and 20.8° respectively. No statistically significant difference was found in intra- and inter-observer recorded results. No statistically significant differences were found when using different bony landmarks. CT assessment of acetabular component inclination and anteversion is accurate, reliable and reproducible when measured using differing bony landmarks as reference points. We recommend measuring acetabular inclination and anteversion from the inferior acetabular wall/teardrop and posterior ischium respectively.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of lipids: ionization and prompt fragmentation patterns.

Ionization and prompt fragmentation patterns of triacylglycerols, phospholipids (PLs) and galactolipids were investigated using matrix-assisted laser desorption/ionization (MALDI). Positive ions of non-nitrogen-containing lipids appeared only in the sodiated form, while nitrogen-containing lipids were detected as both sodiated and protonated adducts. Lipids containing acidic hydroxyls were detected as multiple sodium adducts or deprotonated ions in the positive and negative modes, respectively, with the exception of phosphatidylcholines. The positive MALDI spectra of triacylglycerols contained prompt fragments equivalent to the loss of RCOO(-) from the neutral molecules. Prompt fragment ions [PL-polar head](+) were observed in the positive MALDI spectra of all phospholipids except phosphatidylcholines. The phosphatidylcholines produced only a minor positive fragment corresponding to the head group itself (m/z 184). Galactolipids did not undergo prompt fragmentation. Post-source decay (PSD) was used to examine the source of prompt fragments. PSD fragment patterns indicated that the lipid prompt fragment ions did not originate from the observed molecular ions (sodiated or protonated), and suggested that the prompt fragmentation followed the formation of highly unstable, probably protonated, precursor ions. Pathways leading to the formation of prompt fragment ions are proposed.