Large multiplanar changes to native alignment have no apparent impact on clinical outcomes following total knee arthroplasty.

PURPOSE: This study sought to examine if achieved postoperative alignment when compared to the native anatomy would lead to a difference in Patient Reported Outcome Measures (PROMs), and whether the achieved alignment could be broadly categorised by an accepted alignment strategy. METHODS: A retrospective cohort study of prospectively collected data on patients undergoing single primary or bilateral simultaneous total knee arthroplasty (TKA) was carried out. CT scans were used to determine the mean change ("delta values") between the pre and postoperative; hip-knee-ankle angle, lateral distal femoral angle, medial proximal tibial angle and femoral implant rotation. Femoral implant flexion and tibial implant slope were measured postoperatively. The primary outcome was the relationship of the variables to the change in KOOS pain subscale after one year. The secondary outcome was the number of knees which could be categorised postoperatively to an alignment strategy, and the mean PROMs in each cohort. RESULTS: A total of 296 knees in 261 patients were available for analysis. With regards to the primary outcome, the delta values for each variable did not demonstrate any association with the change in knee injury and osteoarthritis outcome score (KOOS) pain score. Approximately 46% of knees could not be categorised to an alignment strategy based on postoperatively measured alignment, with no significant difference between each cohort with regards to the change in KOOS Pain score. CONCLUSION: Achieved alignment does not consistently match accepted alignment strategies, and appears to confer no benefit to clinical outcomes when the native anatomy is most closely approximated, nor results in poorer outcomes in outliers. This study highlights the importance of routine three dimensional pre and postoperative imaging in clinical practice and for the valid analysis of outcomes in studies on alignment. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

Long leg radiographs underestimate the degree of constitutional varus limb alignment and joint line obliquity in comparison with computed tomography: a radiographic study.

PURPOSE: The purpose of this study was to understand if differences exist between computed tomography (CT) and long leg radiographs (LLR) when defining coronal plane alignment of the lower limb in total knee arthroplasty (TKA). It aimed to identify any such differences between the two imaging modalities by quantifying constitutional limb alignment (arithmetic hip-knee-ankle angle (aHKA), joint line obliquity (JLO) and Coronal Plane Alignment of the Knee (CPAK) type within the same population. METHODS: A retrospective radiographic study compared pre-operative LLR and CT measurements in patients undergoing robotic-assisted TKA. The aHKA, JLO and CPAK types were calculated after measuring the medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA). The primary outcomes were the mean differences in aHKA (MPTA-LDFA), JLO (MPTA + LDFA) and proportions of CPAK types between LLR and CT groups. The secondary outcomes were the differences in CT-derived MPTA values based on four different tibial sagittal landmarks. RESULTS: After exclusions, 465 imaging sets were analysed in 394 patients. There was a statistically significant mean difference between LLR and CT, respectively, for both MPTA (87.5° vs. 86.2°; p < 0.01) and LDFA (88.7° vs. 87.3°; p < 0.01). There were also statistically significant differences for aHKA (- 0.2° vs. - 1.1°) and JLO (175.1° vs. 173.4°) for LLR and CT, respectively (both p < 0.01). CT increased the proportion of patients with CPAK Type I (constitutional varus aHKA, apex distal JLO) and CPAK Type II (neutral aHKA, apex distal JLO), and decreased numbers of CPAK Types III-VI. There were significant mean differences in the MPTA using varying sagittal landmarks. CONCLUSION: Alignment determined by LLRs underestimates the magnitude of both constitutional varus alignment and joint line obliquity compared to CT, differences that notably increase the proportions of patients included in CPAK Types I and II. These distinctions are primarily due to underestimation of proximal tibial varus when measured on LLRs compared to CT, which more specifically defines articular weight-bearing points. LEVEL OF EVIDENCE: III.

Does Choice of Patellar Implant in Total Knee Arthroplasty Matter?: A Randomized Comparative Trial of 3 Commonly Used Designs.

BACKGROUND: There is currently a lack of evidence to identify the optimal patellar implant design in total knee arthroplasty (TKA). The aim of this study was to assess clinical, intraoperative, radiographic, and scintigraphic differences between inlay (IN), onlay round (OR), and onlay oval (OO) patellar implants. METHODS: A parallel-group, double-blinded, randomized trial compared IN, OR, and OO patellar implants using the same posterior-stabilized TKA prosthesis for each. Patient outcomes were prospectively followed for a minimum of 2 years, with survivorship outcomes followed for a mean of 5 years. The primary outcome was the between-group differences in the mean Kujala score change from preoperatively to 2 years postoperatively. The secondary outcomes included differences in other knee-specific and general health outcomes, intraoperative characteristics, radiographic parameters, patellar vascularity, and implant survivorship. RESULTS: A total of 121 participants (40 in the IN group, 41 in OR group, 40 in the OO group) were allocated to 1 of 3 implant designs. At 2 years postoperatively, there were no significant differences in Kujala score changes between groups (p = 0.7; Kruskal-Wallis test). Compared with the IN group, the OR group showed greater improvements in Knee injury and Osteoarthritis Outcome Score (KOOS) Activities of Daily Living and in KOOS Quality of Life compared with the OO group. However, the OO design exhibited better bone coverage and lower lateral facetectomy rates compared with the IN and OR designs. The IN group had more lateral contact compared with the OO group (p = 0.02; Fisher exact test), but the overall value for lateral contact was not significant (p = 0.09; chi-square test). There were no differences in postoperative scintigraphic vascularity (p = 0.8; chi-square test). There was 1 revision for infection at 3 years postoperatively in the OO group, and no revision in the other groups. CONCLUSIONS: Patellar design did not influence patellofemoral outcomes or survivorship. However, OR implants showed improvements in some secondary patient-reported outcome measures, and OO implants exhibited superior bone coverage and improvements in several intraoperative, radiographic, and scintigraphic outcomes. These findings, combined with superior long-term implant survivorship from previous studies, add support for the use of onlay designs in TKA. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Arithmetic hip-knee-ankle angle and stressed hip-knee-ankle angle: equivalent methods for estimating constitutional lower limb alignment in kinematically aligned total knee arthroplasty.

PURPOSE: Kinematically aligned total knee arthroplasty (KA TKA) relies on precise determination of constitutional alignment to set resection targets. The arithmetic hip-knee-ankle angle (aHKA) is a radiographic method to estimate constitutional alignment following onset of arthritis. Intraoperatively, constitutional alignment may also be approximated using navigation-based angular measurements of deformity correction, termed the stressed HKA (sHKA). This study aimed to investigate the relationship between these methods of estimating constitutional alignment to better understand their utility in KA TKA. METHODS: A radiological and intraoperative computer-assisted navigation study was undertaken comparing measurements of the aHKA using radiographs and computed tomography (CT-aHKA) to the sHKA in 88 TKAs meeting the inclusion criteria. The primary outcome was the difference in the paired means between the three methods to determine constitutional alignment (aHKA, CT-aHKA, sHKA). Secondary outcomes included testing agreement across measurements using Bland-Altman plots and analysis of subgroup differences based on different patterns of compartmental arthritis. RESULTS: There were no statistically significant differences between any paired comparison or across groups (aHKA vs. sHKA: 0.1°, p = 0.817; aHKA vs. CT-aHKA: 0.3°, p = 0.643; CT-aHKA vs. sHKA: 0.2°, p = 0.722; ANOVA, p = 0.845). Bland-Altman plots were consistent with good agreement for all comparisons, with approximately 95% of values within limits of agreement. There was no difference in the three paired comparisons (aHKA, CT-aHKA, and sHKA) for knees with medial compartment arthritis. However, these findings were not replicated in knees with lateral compartment arthritis. CONCLUSIONS: There was no significant difference between the arithmetic HKA (whether obtained using CT or radiographs) and the stressed HKA in this analysis. These findings further validate the preoperative arithmetic method and support use of the intraoperative stressed HKA as techniques to restore constitutional lower limb alignment in KA TKA. LEVEL OF EVIDENCE: III.

Multicentre collaborative cohort study of the use of Kirschner wires for the management of supracondylar fractures in children.

PURPOSE: Supracondylar fractures of the humerus cause significant morbidity in children. Nerve damage and loss of fracture reduction are common recognised complications in patients with this injury. Uncertainty surrounds the optimal Kirschner wire configuration and diameter for closed reduction and pinning of these fractures. This study describes current practice and examined the association between wire configuration or diameter and outcomes (clinical and radiological) in the operative management of paediatric supracondylar fractures. METHODS: Children presenting with Gartland II or III supracondylar fractures at five hospitals in south-west England were eligible for inclusion. Collaborators scrutinised paper and electronic case notes. Outcome measures were maintenance of reduction and iatrogenic nerve injury. RESULTS: Altogether 209 patients were eligible for inclusion: 15.7% had a documented neurological deficit at presentation; 3.9% who were neurologically intact at presentation sustained a new deficit caused by treatment and 13.4% experienced a clinically significant loss of reduction following fixation. Maintenance of reduction was significantly better in patients treated specifically with crossed ×3 Kirschner wire configuration compared to all other configurations. The incidence of iatrogenic nerve injury was not significantly different between groups treated with different wire configurations. CONCLUSION: We present a large multicentre cohort study showing that crossed ×3 Kirschner wires are associated with better maintenance of reduction than crossed ×2 or lateral entry wires. Greater numbers would be required to properly investigate nerve injury relating to operative management of supracondylar fractures. We found significant variations in practice and compliance with the British Orthopaedic Association Standard for Trauma (BOAST) 11 guidelines.

Design and Evaluation of a Percutaneous Fragment Manipulation Device for Minimally Invasive Fracture Surgery.

Reduction of fractures in the minimally invasive (MI) manner can avoid risks associated with open fracture surgery. The MI approach requires specialized tools called percutaneous fragment manipulation devices (PFMD) to enable surgeons to safely grasp and manipulate fragments. PFMDs developed for long-bone manipulation are not suitable for intra-articular fractures where small bone fragments are involved. With this study, we offer a solution to potentially move the current fracture management practice closer to the use of a MI approach. We investigate the design and testing of a new PFMD design for manual as well as robot-assisted manipulation of small bone fragments. This new PFMD design is simulated using FEA in three loading scenarios (force/torque: 0 N/2.6 Nm, 75.7 N/3.5 N, 147 N/6.8 Nm) assessing structural properties, breaking points, and maximum bending deformations. The PFMD is tested in a laboratory setting on Sawbones models (0 N/2.6 Nm), and on ex-vivo swine samples (F = 80 N ± 8 N, F = 150 ± 15 N). A commercial optical tracking system was used for measuring PFMD deformations under external loading and the results were verified with an electromagnetic tracking system. The average error difference between the tracking systems was 0.5 mm, being within their accuracy limits. Final results from reduction maneuvers performed both manually and with the robot assistance are obtained from 7 human cadavers with reduction forces in the range of (F = 80 N ± 8 N, F = 150 ± 15 N, respectively). The results show that structurally, the system performs as predicted by the simulation results. The PFMD did not break during ex-vivo and cadaveric trials. Simulation, laboratory, and cadaveric tests produced similar results regarding the PFMD bending. Specifically, for forces applied perpendicularly to the axis of the PFMD of 80 N ± 8 N deformations of 2.8, 2.97, and 3.06 mm are measured on the PFMD, while forces of 150 ± 15 N produced deformations of 5.8, 4.44, and 5.19 mm. This study has demonstrated that the proposed PFMD undergoes predictable deformations under typical bone manipulation loads. Testing of the device on human cadavers proved that these deformations do not affect the anatomic reduction quality. The PFMD is, therefore, suitable to reliably achieve and maintain fracture reductions, and to, consequently, allow external fracture fixation.

Robot-Assisted Fracture Surgery: Surgical Requirements and System Design.

The design of medical devices is a complex and crucial process to ensure patient safety. It has been shown that improperly designed devices lead to errors and associated accidents and costs. A key element for a successful design is incorporating the views of the primary and secondary stakeholders early in the development process. They provide insights into current practice and point out specific issues with the current processes and equipment in use. This work presents how information from a user-study conducted in the early stages of the RAFS (Robot Assisted Fracture Surgery) project informed the subsequent development and testing of the system. The user needs were captured using qualitative methods and converted to operational, functional, and non-functional requirements based on the methods derived from product design and development. This work presents how the requirements inform a new workflow for intra-articular joint fracture reduction using a robotic system. It is also shown how the various elements of the system are developed to explicitly address one or more of the requirements identified, and how intermediate verification tests are conducted to ensure conformity. Finally, a validation test in the form of a cadaveric trial confirms the ability of the designed system to satisfy the aims set by the original research question and the needs of the users.

Image-Guided Surgical Robotic System for Percutaneous Reduction of Joint Fractures.

Complex joint fractures often require an open surgical procedure, which is associated with extensive soft tissue damages and longer hospitalization and rehabilitation time. Percutaneous techniques can potentially mitigate these risks but their application to joint fractures is limited by the current sub-optimal 2D intra-operative imaging (fluoroscopy) and by the high forces involved in the fragment manipulation (due to the presence of soft tissue, e.g., muscles) which might result in fracture malreduction. Integration of robotic assistance and 3D image guidance can potentially overcome these issues. The authors propose an image-guided surgical robotic system for the percutaneous treatment of knee joint fractures, i.e., the robot-assisted fracture surgery (RAFS) system. It allows simultaneous manipulation of two bone fragments, safer robot-bone fixation system, and a traction performing robotic manipulator. This system has led to a novel clinical workflow and has been tested both in laboratory and in clinically relevant cadaveric trials. The RAFS system was tested on 9 cadaver specimens and was able to reduce 7 out of 9 distal femur fractures (T- and Y-shape 33-C1) with acceptable accuracy (≈1 mm, ≈5°), demonstrating its applicability to fix knee joint fractures. This study paved the way to develop novel technologies for percutaneous treatment of complex fractures including hip, ankle, and shoulder, thus representing a step toward minimally-invasive fracture surgeries.

Intra-operative fiducial-based CT/fluoroscope image registration framework for image-guided robot-assisted joint fracture surgery.

PURPOSE: Joint fractures must be accurately reduced minimising soft tissue damages to avoid negative surgical outcomes. To this regard, we have developed the RAFS surgical system, which allows the percutaneous reduction of intra-articular fractures and provides intra-operative real-time 3D image guidance to the surgeon. Earlier experiments showed the effectiveness of the RAFS system on phantoms, but also key issues which precluded its use in a clinical application. This work proposes a redesign of the RAFS's navigation system overcoming the earlier version's issues, aiming to move the RAFS system into a surgical environment. METHODS: The navigation system is improved through an image registration framework allowing the intra-operative registration between pre-operative CT images and intra-operative fluoroscopic images of a fractured bone using a custom-made fiducial marker. The objective of the registration is to estimate the relative pose between a bone fragment and an orthopaedic manipulation pin inserted into it intra-operatively. The actual pose of the bone fragment can be updated in real time using an optical tracker, enabling the image guidance. RESULTS: Experiments on phantom and cadavers demonstrated the accuracy and reliability of the registration framework, showing a reduction accuracy (sTRE) of about [Formula: see text] (phantom) and [Formula: see text] (cadavers). Four distal femur fractures were successfully reduced in cadaveric specimens using the improved navigation system and the RAFS system following the new clinical workflow (reduction error [Formula: see text], [Formula: see text]. CONCLUSION: Experiments showed the feasibility of the image registration framework. It was successfully integrated into the navigation system, allowing the use of the RAFS system in a realistic surgical application.

Complex instability of the elbow.

Injuries to the elbow are commonly encountered in orthopaedic practice. They range from low energy, simple isolated fractures, to high energy complex fracture dislocations with severe ligamentous disruption. Recognising the precise pattern of injury is critical in restoring elbow function and preventing chronic instability, pain and weakness. This article discusses the important osseous and ligamentous stabilisers of the elbow joint and provides management protocols for the common patterns of complex injury encountered by the practising surgeon.

Vision-based real-time position control of a semi-automated system for robot-assisted joint fracture surgery.

PURPOSE: Joint fracture surgery quality can be improved by robotic system with high-accuracy and high-repeatability fracture fragment manipulation. A new real-time vision-based system for fragment manipulation during robot-assisted fracture surgery was developed and tested. METHODS: The control strategy was accomplished by merging fast open-loop control with vision-based control. This two-phase process is designed to eliminate the open-loop positioning errors by closing the control loop using visual feedback provided by an optical tracking system. Evaluation of the control system accuracy was performed using robot positioning trials, and fracture reduction accuracy was tested in trials on ex vivo porcine model. RESULTS: The system resulted in high fracture reduction reliability with a reduction accuracy of 0.09 mm (translations) and of [Formula: see text] (rotations), maximum observed errors in the order of 0.12 mm (translations) and of [Formula: see text] (rotations), and a reduction repeatability of 0.02 mm and [Formula: see text]. CONCLUSIONS: The proposed vision-based system was shown to be effective and suitable for real joint fracture surgical procedures, contributing a potential improvement of their quality.

Preliminary analysis of force-torque measurements for robot-assisted fracture surgery.

Our group at Bristol Robotics Laboratory has been working on a new robotic system for fracture surgery that has been previously reported [1]. The robotic system is being developed for distal femur fractures and features a robot that manipulates the small fracture fragments through small percutaneous incisions and a robot that re-aligns the long bones. The robots controller design relies on accurate and bounded force and position parameters for which we require real surgical data. This paper reports preliminary findings of forces and torques applied during bone and soft tissue manipulation in typical orthopaedic surgery procedures. Using customised orthopaedic surgical tools we have collected data from a range of orthopaedic surgical procedures at Bristol Royal Infirmary, UK. Maximum forces and torques encountered during fracture manipulation which involved proximal femur and soft tissue distraction around it and reduction of neck of femur fractures have been recorded and further analysed in conjunction with accompanying image recordings. Using this data we are establishing a set of technical requirements for creating safe and dynamically stable minimally invasive robot-assisted fracture surgery (RAFS) systems.

A review of techniques for gene therapy in bone healing.

Gene therapy has been successfully used in several areas of medicine as a technique to either alter defective genes or as method to enable delivery of therapeutic proteins. Despite advances in surgical and pharmaceutical interventions for diseases of bone regeneration and healing, results in certain patient groups remain sub-optimal. With this consideration, gene therapy is currently being investigated as a means of facilitating healing and improving outcomes. Two broad techniques which are currently utilised by research teams are discussed in this review; ex vivo and in vivo. The underlying principle is similar in each case; the use of gene therapy to alter target cells to deliver proteins which facilitate bone regeneration. However, whereas ex vivo techniques involve performing genetic manipulations outside the body and then introducing the altered cells to the desired site, in vivo techniques execute genetic manipulations inside the body by the introduction of vectors directly to the desired location. Results from small animal models for both techniques are promising, however, further research is required to demonstrate both safety and efficacy prior to any future clinical application.

Systematic review of randomized controlled trials comparing efficacy of crossed versus lateral K-wire fixation in extension type Gartland type III supracondylar fractures of the humerus in children.

Supracondylar fractures of the humerus occur frequently in children and account for approximately 70% of all elbow fractures. The aim of this systematic review is to critically appraise randomized controlled trials in the literature comparing the outcome of surgical treatment of extension type Gartland III supracondylar fractures using either a cross pin configuration or lateral pins only for fixation in terms of the stability of fixation and the incidence of encountered complications. Only 4 randomized trials were found over the past 10 years. These were reviewed according to the CONSORT 2010 check list. No study found any significant statistical difference in terms of loss of reduction between the two groups, suggesting similar stability of both constructs. There is currently, however, no Level 1 evidence comparing the outcome of crossed pinning versus lateral entry pinning in extension type Gartland III supracondylar fracture. Additionally, the current highest level evidence discussed above has limitations ranging from small sample size to insufficient data on clinical outcome. Therefore we cannot draw any firm conclusions on the above evidence. We suggest that future RCTs take into account the recent evidence on fixation by including three lateral pins and larger diameter pins in their cohorts.

Enhanced recovery program in total hip arthroplasty.

BACKGROUND: Enhanced recovery program (ERP) was implemented to optimize the hospital stay in total hip arthroplasty. This study assessed the effects of optimizing preoperative and perioperative care using enhanced recovery (ER) on patients undergoing Total hip arthroplasty. MATERIALS AND METHODS: We compared a prospective group of 64 patients on the ER program with a historic cohort of 63 patients that received conventional care (non ER). RESULTS: ER patients were discharged earliest from hospital [mean length of stay (LOS) 5.3 days, median 4; P < 0.001] as compared to a mean of 8.3 days among non ER patients. Comparison based on American Association of Anesthesiologists (ASA) grades, preoperative hemoglobin, and body mass index (BMI) revealed that patients with ASA grade 3, preoperative hemoglobin of <14 g/dl, and BMI >30 on ER program spent shorter time in hospital as compared to the non ER's conventionally treated patients with more favorable physiological parameters of ASA grade 1 and 2, preoperative hemoglobin of >14 g/dl, and BMI <30. CONCLUSION: The ER protocol is universally beneficial and confers an advantage regardless of the patients' preoperative condition.

Patellofemoral arthroplasty: a systematic review of the literature.

Identification and management of patients with isolated patellofemoral osteoarthritis are challenging. Many of these patients present at a young age and it is important to distinguish degenerative change in the patellofemoral articulation from the other various causes of anterior knee pain. Once the diagnosis of isolated patellofemoral arthrosis has been made non-operative and conservative surgical techniques should be exhausted fully before prosthetic arthroplasty is considered. This review focuses on the use of arthroplasty for isolated patellofemoral arthrosis, in particular comparing the use of total knee against selective patellofemoral joint replacements.