Background. Non-invasive hemoglobin measurement was introduced to potentially eliminate blood draws postoperatively. We compared the accuracy and effectiveness of a non-invasive hemoglobin measurement system with a traditional blood draw in patients undergoing total joint arthroplasty. Methods. After IRB approval, 100 consecutive patients undergoing primary total hip or knee arthroplasty had their hemoglobin level tested by both traditional blood draw and a non-invasive hemoglobin monitoring system. Results were analyzed for the entire group, further stratifying patients based on gender, race, surgery (THA versus TKA), and post-operative hemoglobin level. Finally, we compared financial implications and patient satisfaction with the device. Paired t-test with 0.05 conferring significance was used. Stratified analyses of the absolute difference between the two measures were assessed using Mann- Whitney test. To assess the level of agreement between the two measures, the concordance correlation coefficient (CCC) was calculated. Results. Mean blood-draw hemoglobin value on POD1 was 11.063 ± 1.39 g/dL and 11.192 ± 1.333 g/dL with the non-invasive device. For all patients, the mean absolute difference between the two methods was 0.13 g/dL (p = 0.30). The CCC between the two methods was 0.58, conferring a moderate to strongly positive linear relationship (Figure 1). Non-invasive measurement was preferred by 100% of patients with a mean VAS score of 0/10. Additionally, the cost savings with the non-invasive system was $16.50 per patient. Discussion. Overall, there was no significant difference between the hemoglobin level obtained by traditional laboratory methods versus the Masimo Radical-7 system on post-operative day #1 in patients who underwent total joint arthroplasty. In the minority of patients (19%) who had a hemoglobin level of less than 10 g/dL, the difference between the two methods was statistically significant. Additionally, 100% of patients preferred the Masimo device to a traditional blood draw and the Masimo device was substantially cheaper. While further investigation of non-invasive hemoglobin monitoring systems is necessary, particularly in patients with a post-operative hemoglobin of less than 10 g/dL, our study shows that the Masimo Radical-7 device provides an accurate, preferable, and less expensive alternative to a traditional blood draw after total joint replacement. Conclusion. Overall, the non-invasive hemoglobin monitoring system offered a similar hemoglobin reading to the standard lab-draw reading, while improving satisfaction and lowering cost. The system relies on adequate perfusion for measurement, and our study demonstrated that lower hemoglobin values may reduce finger-tip perfusion and affect the hemoglobin reading

INTRODUCTION. Navigation systems have proved allowing performing measurement of the lower limb axis with a good accuracy, but the mandatory use of reference pins or screws limit their use to the operating room. The use of non-invasive navigation systems has been suggested to overcome this limitation. We conducted a prospective study to assess the validity of such a measurement system with non-invasive fixation of the reference arrays. The main goal was to compare this method with a standard, invasive navigation system requiring bony fixation of the arrays. The following hypothesis was tested: there will be a significant difference between the simultaneous measurement of the mechanical femoro-tibial angle by a standard navigation system and by the non-invasive navigation system. MATERIAL AND METHODS. 20 patients scheduled for total or partial knee arthroplasty were included after giving their informed consent. There were 7 men and 13 women with a median age of 65 years (range, 55 to 90). The median coronal deformation measured by X-rays was 8° of varus (range, 5° valgus to 22 ° varus). The same navigation system was used for both invasive and non-invasive measurements, but the basic algorithms were adapted for the non-invasive technique. For the non-invasive technique, metallic plates were strapped on the thigh and the calf to allow arrays fixation (fig. 1). Coronal femoro-tibial mechanical angle (CMFA) in maximal extension without stress was recorded by the non invasive system. This non-invasive analysis was immediately followed by surgery, and the same angle was measured intra-operatively with the invasive system. Comparisons between non-invasive and invasive measurements were performed using a Wilcoxon test, after checking that their distribution followed a normal distribution, and an equivalence testing with limits of ±3°. The correlation between the two sets of measurements was analyzed using a correlation test Spearman rank. The analysis of the concordance of the two sets of measurements was performed using Bland and Altman tests. The significance level p was set at 0.05. RESULTS. There was no significant difference between non invasive and invasive measurements of the CMFA in full extension. There was a good correlation (fig. 2) and a good concordance (fig. 3) between both measurements. DISCUSSION. The non invasive measurement technique system seems to be as accurate as conventional, invasive navigation. CONCLUSION. This technique might be a valuable alternative to long leg x-rays, with a good accuracy but without radiation exposure. For any figures or tables, please contact the authors directly

Conventional computer navigation systems using bone fixation have been validated in measuring anteroposterior (AP) translation of the tibia. Recent developments in non-invasive skin-mounted systems may allow quantification of AP laxity in the out-patient setting. We tested cadaveric lower limbs (n=12) with a commercial image free navigation system using passive trackers secured by bone screws. We then tested a non-invasive fabric-strap system. The lower limb was secured at 10° intervals from 0° to 60° knee flexion and 100N of force applied perpendicular to the tibial tuberosity using a secured dynamometer. Repeatability coefficient was calculated both to reflect precision within each system, and demonstrate agreement between the two systems at each flexion interval. An acceptable repeatability coefficient of ≤3mm was set based on diagnostic criteria for ACL insufficiency when using other mechanical devices to measure AP tibial translation. Precision within the individual invasive and non-invasive systems measuring AP translation of the tibia was acceptable throughout the range of flexion tested (repeatability coefficient ≤1.6mm). Agreement between the two systems was acceptable when measuring AP laxity between full extension and 40° knee flexion (repeatability coefficient ≤2.1mm). Beyond 40° of flexion, agreement between the systems was unacceptable (repeatability coefficient >3mm). These results indicate that from full knee extension to 40° flexion, non-invasive navigation-based quantification of AP tibial translation is as accurate as the standard invasive system, particularly in the clinically and functionally important range of 20° to 30° knee flexion. This could be useful in diagnosis and post-operative follow-up of ACL pathology

The knee joint displays a wide spectrum of laxity, from inherently tight to excessively lax even within the normal, uninjured population. The assessment of AP knee laxity in the clinical setting is performed by manual passive tests such as the Lachman test. Non-invasive assessment based on image free navigation has been clinically validated and used to quantify mechanical alignment and coronal knee laxity in early flexion. When used on cadavers the system demonstrated good AP laxity results with flexion up to 40°. This study aimed to validate the repeatability of the assessment of antero-posterior (AP) knee joint laxity using a non-invasive image free navigation system in normal, healthy subjects. Twenty-five healthy volunteers were recruited and examined in a single centre. AP translation was measured using a non-invasive navigation system (PhysioPilot) consisting of an infrared camera, externally mounted optical trackers and computer software. Each of the volunteers had both legs examined by a single examiner twice (two registrations). The Lachman test was performed through flexion in increments of 15°. Coefficients of Repeatability (CR) and Interclass Correlation Coefficients (ICC) were used to validate AP translation. The acceptable limits of agreement for this project were set at 3mm for antero-posterior tibial translation. The most reliable and repeatable AP translation assessments were at 30° and 45°, demonstrating good reliability (ICC 0.82, 0.82) and good repeatability (CR 2.5, 2.9). The AP translation assessment at 0°, 15°, 75° and 90° demonstrated moderate reliability (ICC ≤ 0.75), and poor repeatability (CR ≥3.0mm). The non-invasive system was able to reliably and consistently measure AP knee translation between 30° and 45° flexion, the clinically relevant range for this assessment. This system could therefore be used to quantify abnormal knee laxity and improve the assessment of knee instability and ligamentous injuries in a clinic setting

Introduction:. Non-invasive extendible endoprostheses (NIEE) were primarily developed for salvage after musculo-skeletal tumour surgery in the immature skeleton. However, they may also have a unique application to manage complex limb reconstruction in revision surgery to address limb-length inequality in the mature skeleton. The aim of this study is to present the minimum 2 –year results of using non-invasive extendible endoprostheses for complex lower limb reconstruction. Methods:. Between 2004 and 2013, 21 patients were treated with 23 NIEE. The indication for surgery was salvage of infected prosthesis following primary tumor resection in 6 cases, aseptic prosthesis failure after primary tumour resection in 5 cases, aseptic non-tumor prosthesis failure in 1 case, infected non-tumor prosthesis in 8 cases and symptomatic non-union of graft reconstruction in 3 cases. There were 14 male and 7 female patients with a mean age of 49.8 years (range 19–81). Results:. The mean length gained was 41.5 mm (range 0 to 90) requiring a mean of 7 (0–25) lengthening episodes performed in the outpatient department. 4 cases required revision surgery for persistent infection. These had multiple previous surgeries and inadequate soft tissue coverage. There were also 2 early dislocations in one patient treated successfully with lengthening and 1 failure to achieve desired length. The Mean Musculoskeletal Tumour Society rating score was 19. Conclusion:. The use of NIEE is associated with good functional outcome and offers yet another way of limb salvage. A modest complication rate is noted in this series, which reflects the complexity of these cases

Non-invasive expandable prostheses for limb salvage tumour surgery were first used in 2002. These implants allow ongoing lengthening of the operated limb to maintain limb-length equality and function while avoiding unnecessary repeat surgeries and the phenomenon of anniversary operations. A large series of skeletally immature patients have been treated with these implants at the two leading orthopaedic oncology centres in England (Royal National Orthopaedic Hospital, Stanmore, and Royal Orthopaedic Hospital, Birmingham). An up to date review of these patients has been made, documenting the relevant diagnoses, sites of tumour and types of implant used. 87 patients were assessed, with an age range of 5 to 17 years and follow up range of up to 88 months. Primary diagnosis was osteosarcoma, followed by Ewing's sarcoma. We implanted distal femoral, proximal femoral, total femoral and proximal tibial prostheses. All implants involving the knee joint used a rotating hinge knee. 6 implants reached maximum length and were revised. 8 implants had issues with lengthening but only 4 of these were identified as being due to failure of the lengthening mechanism and were revised successfully. Deep infection was limited to 5% of patients. Overall satisfaction was high with the patients avoiding operative lengthening and tolerating the non-invasive lengthenings well. Combined with satisfactory survivorship and functional outcome, we commend its use in the immature population of long bone tumour cases

Clinically applied methods of assessing implant fixation and implant loosening are of sub-optimal precision, leading to the risk of unsecure indication of revision surgery and late recognition of bone defects. Loosening diagnosis involving measuring the eigenfrequencies of implants has its roots in the field of dentistry. The changing of the eigenfrequencies of the implant-bone-system due to the loosening state can be measured as vibrations or structure-borne sound. In research, vibrometry was studied using an external shaker to excite the femur-stem-system of total hip replacements and to measure the resulting frequencies by integrated accelerometers or by ultrasound. Since proper excitation of implant components seems a major challenge in vibrometry, we developed a non-invasive method of internal excitation creating an acoustic source directly inside the implant. In the concept proposed for clinical use, an oscillator is integrated in the implant, e.g. the femoral stem of a total hip replacement. The oscillator consists of a magnetic or magnetisable spherical body which is fixed on a flat steel spring and is excited electromagnetically by a coil placed outside the patient. The oscillator impinges inside the implant and excites this to vibrate in its eigenfrequency. The excitation within the bending modes of the implant leads to a sound emission to the surrounding bone and soft tissue. The sound waves are detected by an acoustic sensor which is applied on the patient's skin. Differences in the signal generated result from varying level of implant fixation. The sensor principle was tested in porcine foreleg specimens with a custom-made implant. Influence of the measurement location at the porcine skin and different levels of fixation were investigated (press-fit, slight loosening, advanced loosening) and compared to the pull-out strength of the implant. Evaluation of different parameters, especially the frequency spectrum resulted in differences of up to 12% for the comparison between press-fit and slight loosening, and 30% between press-fit and advanced loosening. A significant correlation between the measured frequency and the pull-out strength for different levels of fixation was found. Based on these findings, an animal study with sensor-equipped bone implants was initiated using a rabbit model. The implants comprised an octagonal cross-section and were implanted into a circular drill hole at the distal femur. Thereby, definite gaps were realized between bone and implant initially. After implantation, the bone growth around the implant started and the gaps were successively closed over postoperative period. Consequently, since the tests had been started with a loose implant followed by its bony integration, a reverse loosening situation was simulated. In weekly measurements of the eigenfrequencies using the excitation and sensor system, the acoustic signals were followed up. Finally, after periods of 4 and 12 weeks after implantation, the animals were sacrificed and pull-out tests of the implants were performed to measure the implant fixation. The measured implant fixation strengths at the endpoint of each animal trial were correlated with the acoustic signals recorded

INTRODUCTION. In patients with neural disorders such as cerebral palsy, three-dimensional marker-based motion analysis has evolved to become a well standardized procedure with a large impact on the clinical decision-making process. On the other hand, in knee arthroplasty research, motion analysis has been little used as a standard tool for objective evaluation of knee joint function. Furthermore, in the available literature, applied methodologies are diverse, resulting in inconsistent findings [1]. Therefore we developed and evaluated a new motion analysis framework to enable standardized quantitative assessment of knee joint function. MATERIALS AND METHODS. The proposed framework integrates a custom-defined motion analysis protocol with associated reference database and a standardized post-processing step including statistical analysis. Kinematics are collected using a custom-made marker set defined by merging two existing protocols and combine them with a knee alignment device. Following a standing trial, a star-arc hip motion pattern and a set of knee flexion/extension cycles allowing functional, subject-specific calibration of the underlying kinematic model, marker trajectories are acquired for three trials of a set of twelve motor tasks: walking, walking with crossover turn, walking with sidestep turn, stair ascent, stair descent, stair descent with crossover turn, stair descent with sidestep turn, trunk rotations, chair rise, mild squat, deep squat and lunge. This specific set of motor tasks was selected to cover as much as possible common daily life activities. Furthermore, some of these induce greater motion at the knee joint, thus improving the measurement-to-error ratio. Kinetics are acquired by integrating two forceplates in the walkway. Bilateral muscle activity of 8 major muscles is monitored with a 16 channel wireless electromyography (EMG) system. Finally, custom-built software with an associated graphical user interface was created for automated and flexible analysis of gait lab data, including repeatability analysis, analysis of specific kinematic, kinetic and spatiotemporal parameters and statistical comparisons. RESULTS. Following ethical approval and informed consent, the proposed framework was successfully applied in a control group of 80 normal subjects within a wide age-range (age: 54.5Y±19.1; BMI: 25.5±4.0; 40M/40F; 60 Caucasian, 20 Asian) thus constructing the reference database for control. Moreover, the same framework was applied successfully in a randomly selected group of 10 patients with a bi-compartmental knee replacement (BKR) (age: 67.3Y±5.3; BMI: 29.7±3.1; time post-op: 1.65Y±0.4; 2M/8F Caucasian). Comparison between these patients and age-matched controls demonstrates that, for a large range of motor tasks, knee joint kinematics after BKR are as much consistent with the healthy controls (coefficient of multiple correlation (CMC) =0.49) as the consistency within a group of controls or BKR-subjects individually (CMC=0.52). Nevertheless, also significant differences (p<0.0167) were identified which are indicative for retention of pre-operative motion patterns and/or remaining compensations. CONCLUSION. The proposed framework allows in-vivo evaluation of knee joint performance in a standardized, objective and non-invasive way. It is applicable in both healthy subjects and knee replacement patients and is shown to be sufficiently sensitive to detect even relatively small differences between the two populations

Introduction. Superficial wound complications can occur in up to 10% of total knee arthroplasty (TKA) patients and have been associated with deep infection. The ideal material for TKA closure should fulfill the following requirements: 1) fast intraoperative application, 2) minimal wound complications and discomfort, and 3) can be removed by patients without a home care visit. We present our experience with a novel, non-invasive, removable skin closure system compared to conventional staple closure. Methods. We prospectively evaluated 105 consecutive patients who underwent unilateral or bilateral primary TKA and received skin closure consisting of the Zip 16 Surgical Skin Closure System (Zipline) for skin. All procedures were performed a by single surgeon (SBH) using a mini-midvastus approach. All patients were mobilized on the day of surgery and received 2 weeks of Rivaroxaban thromboprophylaxis. Patient demographics, medical comorbidities, in-hospital complications and wound healing and complications during the first 6-week post-operatively were recorded. Data was compared to a previous TKA cohort of 1,001 patients from the same surgeon who received staples for closure and warfarin for thromboprophylaxis. Results. Zip and staple patient groups had similar age, gender and BMI. There was a higher percentage of diabetic patients in the Zip closure group (12% vs. 10%). All 105 patients with Zip closure removed dressings themselves and had healed wounds with no noted drainage or blistering at six-weeks. Two patients had protruding subcutaneous vicryl stitches that were removed. In the staple group there were six knees (0.6%) that had wound drainage with 2 (0.2%) requiring reoperation for debridement and reclosure. Discussion. In our experience, the Zip 16 Surgical Skin Closure System is easy to apply, avoids the need for home care or office visit and had fewer wound complications compared to staples. Results have been positive despite the study cohort having a higher number of diabetic patients and using an anticoagulant which may be associated with higher risk of wound problems

Treatment for osteoarthritis (OA) has traditionally focused on joint replacement for end-stage disease. An increasing number of surgical and pharmaceutical strategies for disease prevention have now been proposed. However, these require the ability to identify OA at a stage when it is potentially reversible, and detect small changes in cartilage structure and function to enable treatment efficacy to be evaluated within an acceptable timeframe. This has not been possible using conventional imaging techniques but recent advances in musculoskeletal imaging have been significant. In this review we discuss the role of different imaging modalities in the diagnosis of the earliest changes of OA. The increasing number of MRI sequences that are able to non-invasively detect biochemical changes in cartilage that precede structural damage may offer a great advance in the diagnosis and treatment of this debilitating condition.

Cite this article: Bone Joint J 2013;95-B:738–46.

INTRODUCTION

Joint replacement is one of the most common orthopaedic procedures, with over 2 million surgeries performed each year across the globe. Loss of implant fixation, or aseptic loosening, is the leading cause of revision following primary joint replacement, accounting for ∼25% of all revision cases [1]. However, diagnosis of aseptic loosening and its underlying causes remain challenging due to the low sensitivity and specificity of plain radiographs. To address this, we propose a novel approach inspired by [2] involving the use of a self-sensing bone cement (by imparting strain-dependent electrical conductivity or piezoresistivity) combined with electrical impedance tomography (EIT). Piezoresistivity is imparted to cement via incorporation of micro/nanoscale conductive fillers. Therefore mechanical effects such as loosening and cracks will manifest as a conductivity change of the cement. This work explores if EIT is able to detect strains and cracks within the bone cement volume.

Range of motion (ROM) is a well recognised outcome measure following total knee arthroplasty (TKA). Reduced knee flexion can lead to poor outcome after TKA and therefore identification at an early stage is important as it may provide a window for intervention with targeted physiotherapy, closer follow-up and in resistant cases possible manipulation or arthrolysis. ROM combines both flexion and extension and in contrast to flexion, fewer studies have recognised the importance of a lack of full extension or fixed flexion deformity (FFD) following TKA. A residual FFD can increase energy cost, decrease velocity during ambulation and result in pain with knee scores more likely to be diminished than if knee extension was normal. Recognition and early detection of FFD is therefore important. Methods of assessment include by visual estimation or goniometric measurement of knee flexion angle. While goniometers are inexpensive, easy to use and provide more accurate than visual estimates of angles, they have been shown to exhibit poor inter-observer reliability. Therefore they may not be sensitive enough to consistently identify FFD and therefore distinguish between grading systems based on absolute angular limits. The aim of this study was to investigate the accuracy of standard clinical ROM measurement techniques following TKA and determine their reliability for recognising FFD.

Ethical approval was obtained for this study. Thirty patients who were six weeks following TKA had their knee ROM measured. An infrared (IR) tracking system (±1°accuracy) that had been validated against an electro-goniometer was used to give a “true” measurement of the lower limb sagittal alignment with the knee fully extended and maximally flexed while the patient was supine. The patients were also assessed independently by experienced arthroplasty practitioners using a standardised goniometric measurement technique. For goniometric clinically-measured flexion (Clin_flex) and extension (Clin_ext) linear models were generated using IR-measured flexion and extension (IR_flex and IR_ext), BMI and gender as covariables. Data for extension were categorised in none, moderate and severe postoperative FFD as per Ritter et al. 2007 and agreement in classification between the two methods was assessed using the Kappa statistic.

For the linear models for Clin_flex and Clin_ext neither BMI nor gender were significant variables. Therefore the final models were:

Clin_flex = 0.54 + 0.66∗IR_flex (r²_adj = 0.521)

Clin_ext = 0.23 + 0.50∗IR_ext (r²_adj = 0.247)

The model for Clin_flex showed that the IR and clinical measurements coincided at approximately 90° so that for every 10° increase in flexion above 90° clinical measurement only increased by 7° but for every 10° decrease in flexion below 90° clinical measurement only decreased by 7°. The model for Clin_ext showed that the IR and clinical measurements coincided at approximately 0° so that for every 10° increase in FFD angle, clinical measurement only increased by 5° but if the knee went into hyperextension this would be underestimated by the clinical measure. In identifying FFD there was moderate agreement between the two measurements (κ = 0.44). Clinically nine patients were assessed as having FFD but the IR measurements showed 18 patients having FFD, of which nine patients were not identified clinically.

When assessing knee ROM following joint arthroplasty manual goniometric measurements provided a poor estimate of the range when compared to the “true” angle as measured with a validated IR measurement tool. When the knee was held in maximum flexion there was a tendency to both underestimate and overestimate the true angle. However when the knee was held in extension there was a tendency to underestimate which we believe is important as it would underreport both the frequency and magnitude of FFD. In our study, 18 patients had a moderate FFD as identified by the IR system, only half of which were identified by goniometer measurement alone. Studies of comparisons of both visual and manual goniometry measurements of the knee in maximum flexion with lateral radiographs have shown most errors involved an underestimate of true flexion. It has been concluded that it was safer to underestimate knee flexion angle as it would result in higher pick up rate of cases being performing less well. In contrast however, underestimation while in extension is less desirable as it fails to pick-up FFD which may have benefited from intervention had they been identified. It is known that residual FFD can increase energy cost and decrease velocity during ambulation with pain and functional knee scores more likely to be reduced. Recognition and early detection is therefore important. With the use of more accurate systems to identify and measure FFD, such as the one used for this study may in turn allow more timely treatment and therefore hopefully improved outcomes.

Anterior knee pain is one of the most frequently reported musculoskeletal complaints in all age groups. However, patient's complaints are often nonspecific, leading to difficulty in properly diagnosing the condition. One of the causes of pain is the degeneration of the articular cartilage. As the cartilage deteriorates, its ability to distribute the joint reaction forces decreases and the stresses may exceed the pain threshold. Unfortunately, the assessment of the cartilage condition is often limited to a detailed interview with the patient, careful physical examination and x-ray imaging. The X-ray screening may reveal bone degeneration, but does not carry sufficient information of the soft tissues' conditions. More advanced imaging tools such as MRI or CT are available, but these are expensive, time consuming and are only suitable for detection of advanced arthritis. Arthroscopic surgery is often the only reliable option, however due to its semi-invasive nature, it cannot be considered as a practical diagnostic tool. However, as the articular cartilage degenerates, the surfaces become rougher, they produce higher vibrations than smooth surfaces due to higher friction during the interaction. Therefore, it was proposed to detect vibrations non-invasively using accelerometers, and evaluate the signals for their potential diagnostic applications.

Vibration data was collected for 75 subjects; 23 healthy and 52 subjects suffering from knee arthritis. The study was approved by the IRB and an Informed Consent was obtained prior to data collection. Five accelerometers were attached to skin around the knee joint (at the patella, medial and lateral femoral condyles, tibial tuberosity and medial tibial plateau). Each subject performed 5 activities; (1) flexion-extension, (2) deep knee bend, (3) chair rising, (4) stair climbing and (5) stair descent. The vibration and motion components of the signals were separated by a high pass filter. Next, 33 parameters of the signals were calculated and evaluated for their discrimination effectiveness (Figure 1). Finally the pattern recognition method based on Baysian classification theorem was used for classify each signal to either healthy or arthritic group, assuming equal prior probabilities.

The variance and mean of the vibration signals were significantly higher in the arthritic group (p=2.8e-7 and p=3.7e-14, respectively), which confirms the general hypothesis that the vibration magnitudes increase as the cartilage degenerates. Other signal features providing good discrimination included the 99^th quantile, the integral of the vibration signal envelope, and the product of the signal envelope and the activity duration. The pattern classification yielded excellent results with the success rate of up to 92.2% using only 2 features, up to 94.8% using 3 (Figure 2), and 96.1% using 4 features.

The current study proved that the vibrations can be studied non-invasively using a low-cost technology. The results confirmed the hypothesis that the degeneration of the cartilage increases the vibration of the articulating bones. The classification rate obtained in the study is very encouraging, providing over 96% accuracy. The presented technology has certainly a potential of being used as an additional screening methodology enhancing the assessment of the articular cartilage condition.

When performing limb salvage operations for malignant bone tumours in skeletally immature patients, it is desirable to reconstruct the limb with a prosthesis that can be lengthened without surgery at appropriate intervals to keep pace with growth of the contra-lateral side. We have developed a prosthesis that can be lengthened non-invasively. The lengthening is achieved on the principle of electromagnetic induction.

The purpose of this study was to look at our early experience with the use of the Non Invasive Distal Femoral Expandable Endoprosthesis. A prospective study of 17 skeletally immature patients with osteosarcoma of the distal femur, implanted with the prosthesis, was performed at the Royal National Orthopaedic Hospital, Stanmore. The patients were aged between 9 and 15 years (mean 12.1 years) at the time of surgery. Patients were lengthened at appropriate intervals in outpatient clinics. Patients were functionally evaluated using the Musculoskeletal Tumour Society (MSTS) Scoring System and the Toronto Extremity Severity Score (TESS). Average time from the implantation to the last follow-up was 18.2 months (range 14-30 months). The patients have been lengthened by an average of 25mm (4.25-55mm). The mean amount of knee flexion is 125 degrees. The mean MSTS score is 77% (23/30; range 11-29) and the mean TESS score is 72%. There have been two complications: one patient developed a flexion deformity of 25 degrees at the knee joint and one patient died of disseminated metastatic malignancy.

The early results from patients treated using this device have been encouraging. Using this implant avoids multiple surgical procedures and general anaesthesia. This results in low morbidity, cost savings and reduced psychological trauma. We do need additional data regarding the long-term structural integrity of the prosthesis.

Cryocompression therapy is a non-invasive and non-pharmacological modality used in managing acute post-operative inflammation and pain. A prospective, randomised controlled trial (RCT) was undertaken to evaluate the effectiveness of a post-operative cryocompression protocol using the Game Ready™ (GR) device versus usual care on recovery following total knee arthroplasty (TKA). A single centre RCT was conducted with 70 TKAs (68 patients) randomised to a 2-week intervention period consisting of treatment with GR cryocompression (n=33, 33.3% males) or a usual care protocol of ice with static compression using tubigrip (n=35, 54.3% males). Knee range of movement (ROM) (flexion and extension), a visual analogue pain score (VAS) and limb circumference were documented at day 1, 2 and 14, as well as 6 and 12 weeks post-surgery. ROM was also recorded at day 90, while medication use and length of hospital stay were documented. Patient reported outcome measures (PROMs) including the KOOS and patient satisfaction questionnaire were employed. The GR group demonstrated 2.3° more (p=0.05) knee extension ROM overall, as well as 2. 8° more at day 1 (p=0.048), 3.8° at day 14 (p=0.007) and 5.4° at 3 months (p=0.017). There were no group differences (p>0.05) observed in pain (VAS), flexion ROM, limb circumference, opioid use or other PROMs. Across the full cohort, higher pain levels resulted in increased opioid intake (p=0.002), older patients used significantly less opioids (p<0.001) and males reported significantly less pain (VAS) than females (p=0.048). Using GR following TKA is a safe, non-invasive tool that can be used to aid in the post-operative recovery period. Patients using the GR cryocompression device gained significantly more extension ROM compared to the conventional ice with compression group, despite no other group differences

Introduction. Osteomyelitis is a challenge in diagnosis and treatment. 18F-FDG PET-CT provides a non-invasive tool for diagnosing and localizing osteomyelitis with a sensitivity reaching 94% and specificity reaching 100%. We aimed to assess the agreement in identifying the geographic area of infected bone and planned resection on plain X-ray versus 18F-FDG PET-CT. Materials & Methods. Clinical photos and X-rays of ten osteomyelitis patients were shown to ten consultant surgeons; they were asked to draw the area of infection and extent of planned surgical debridement; data will be compared to 18F-FDG PET-CT results. Results. We tested the agreement between the surgeons in every parameter. Regarding height, there was poor agreement between surgeons. Regarding perimeter, the ten surgeons showed low-moderate agreement. The ten surgeons showed a low-moderate agreement for circularity. Results document the variability of assessment and judgement based on plain X-rays. In comparison to PET-CT, All parameters were significantly different in favour of 18F-FDG PET-CT over X-ray (P < 0.001). Conclusions. 18F FDG PET-CT provides a three-dimensional tool for localizing the exact location of the infected bone and differentiating it from the normal bone. Thus, it could be beneficial in precise pre-operative planning and surgical debridement of chronic osteomyelitis

Non-invasive sampling of tumor-derived genetic material in circulation through liquid biopsy may be very beneficial for an accurate diagnosis and evaluation of response to treatment in patients with malignant and benign soft tissue tumors. We previously showed that tumor-derived genomic aberrations can be detected in plasma of patients with leiomyosarcoma (LMS) and leiomyoma (LM). In LMS patients, we also showed that the levels of circulating tumor DNA (ctDNA) correspond with response to treatment. We developed an approach tailored to genomic profile of LMS (characterized by intermediate levels of point mutations and copy number alterations, CNAs). Based on TCGA data, we designed a panel of 89 most frequently mutated genes in LMS, which we profiled in plasma DNA by deep sequencing. In parallel, plasma samples were analyzed by shallow whole genome sequencing for detection of CNAs. With this approach, we detected ctDNA in 71% (20/28) of samples from 6/7 patients with advanced disease with >98% specificity. The combination approach for orthogonal profiling of point mutations and CNAs proved to increase the sensitivity of ctDNA detection. Currently, we seek to further improve the sensitivity of ctDNA detection by refining our capture panel and tracking LMS-specific DNA methylation markers in circulation, in addition to point mutations and CNAs. The ultimate goals of our ctDNA studies are 1) to develop a highly sensitive assay for evaluation of response to therapy and long-term surveillance for patients with LMS, and 2) to develop a blood-based test for accurate pre-operative distinction between LMS and LM. To identify LMS-specific DNA methylation markers, we analyzed a test cohort of 76 LM, 35 uterine LMS and 31 extra-uterine LMS by Illumina Infinium EPIC arrays. We identified differentially methylated CpGs between LM and uterine LMS, and between LM and all LMS using a newly developed custom pipeline in R. The results of this analysis are currently being validated in a new dataset of 41 LM and 153 LMS generated by our group. Recently published (PMID: 34301934) genomic data from new 53 LMS samples are used to refine the panel of the most frequently mutated genes that we identified previously in the LMS TCGA data. Our preliminary analysis of test cohort revealed >270 differentially methylated CpGs between LM and uterine LMS, and >1000 differentially methylated CpGs between LM and all LMS. The preliminary analysis of genomic data shows that the initial panel of 89 frequently mutated genes could be substantially narrowed down to cover only selected tumor suppressor genes. Once validated, these results will be used to refine the ctDNA assay for LMS and LM. Our results point to multiple epigenetic markers that could be used for ctDNA profiling, in addition to point mutations or CNAs. Further validation will allow us to select the most reliable LMS- and LM-specific DNA methylation markers and the most frequently mutated regions across independent datasets, and these markers will be incorporated into our new ctDNA test for a concurrent detection of point mutations, CNAs and DNA methylation markers in circulation

Non-invasive assessment of lower limb mechanical alignment and assessment of knee laxity using navigation technology is now possible during knee flexion owing to recent software developments. We report a comparison of this new technology with a validated commercially available invasive navigation system. We tested cadaveric lower limbs (n=12) with a commercial invasive navigation system against the non-invasive system. Mechanical femorotibial angle (MFTA) was measured with no stress, then with 15Nm of varus and valgus moment. MFTA was recorded at 10° intervals from full knee extension to 90° flexion. The investigator was blinded to all MFTA measurements. Repeatability coefficient was calculated to reflect each system's level of precision, and agreement between the systems; 3° was chosen as the upper limit of precision and agreement when measuring MFTA in the clinical setting based on current literature. Precision of the invasive system was superior and acceptable in all conditions of stress throughout flexion (repeatability coefficient <2°). Precision of the non-invasive system was acceptable from extension until 60° flexion (repeatability coefficient <3°), beyond which precision was unacceptable. Agreement between invasive and non-invasive systems was within 1.7° from extension to 50° flexion when measuring MFTA with no varus / valgus applied. When applying varus / valgus stress agreement between the systems was acceptable from full extension to 20° & 30° knee flexion respectively (repeatability coefficient <3°). Beyond this the systems did not demonstrate sufficient agreement. These results indicate that the non-invasive system can provide reliable quantitative data on MFTA and laxity in the range relevant to knee examination

Background. Clinical and anatomical complications from total knee replacement (TKR) procedures are debilitating, and include weakness, damage, and the loss of native anatomy. As the annual number of primary TKR surgeries in the United States has continued to rise, to a projected 3.48 million in 2030, there has been a concomitant rise in revision surgery. Damage to or loss of native knee anatomy as a result of TKR revision can leave the patient with irreversible knee dysfunction, which is a contra-indication for most TKR systems on the market. This leaves the multi-revision patient with limited medical options. Complete fusion of the joint, known as arthrodesis, is indicated in some cases. Arthrodesis is also commonly indicated for traumatic injury, bone loss, quadriceps extensor mechanism damage, and osteosarcoma. While this treatment may resolve pain and allow a patient to walk, the inability to flex the knee results in considerable functional complications. Patients with arthrodesis are unable to drive, sit in close-quarter spaces, or engage in a significant number of activities of daily living. Product Statement. The authors have developed and patented the Engage Knee System, a novel TKR system that allows a patient to lock and unlock the knee joint by means of a handheld, non-invasive device. An internal locking mechanism is constructed of materials that have been used in orthopedic joint replacements that have been approved through the FDA 510(k) process. A lightweight, handheld magnetic device is used to actuate the locking mechanism. No percutaneous components are required or present. This device allows a patient to lock their knee joint in full extension to ambulate with the functional equivalence of an arthrodesis, but allows a patient to unlock the device and bend the knee to engage in passive activities that would be otherwise difficult or impossible. The IP portfolio for this technology is owned by Clemson University, and they are seeking a partner/licensee to pursue further technology development and validation. Methods. A literature review of knee arthrodesis incidence and prevalence has been published by the inventors. Three- dimensional gait analysis was used to characterize rigid-knee gait kinematics and kinetics to verify potential implant design loads. Multiple physical prototypes of the design were created and implanted in Sawbones synthetic knee models, and a final prototype using industry-standard arthroplasty materials was contract-manufactured. Results. The Engage system is capable of locking and unlocking in full extension with the use of a non-invasive hand-held device. The device will support the loading patterns and magnitudes during stiff knee gait, as estimated through gait analysis and musculoskeletal modeling, when it is locked in full extension. Conclusion. The Engage Knee System bridges the gulf between existing treatments, and addresses not only patients who would otherwise undergo arthrodesis, but also patients who have avoided treatment or who currently undergo high-risk revision procedures. The device is also a viable option for arthrodesis takedown, providing patients who have already undergone arthrodesis a means of regaining knee flexion

Fracture non-union can be as high as 20% in certain clinical scenarios and has a high associated socioeconomic burden. Boron has been shown to regulate the Wnt/β-catenin pathway in other bodily processes. However, this pathway is also critical for bone healing. Here we aim to demonstrate that the local delivery of boric acid can accelerate bone healing, as well as to elucidate how boric acid, via the regulationtheWnt/β-catenin pathway, impacts theosteogenic response of bone-derived osteoclasts and osteoblasts during each phase of bone repair. Bilateral femoral cortical defects were created in 32 skeletally mature C57 mice. On the experimental side, boric acid (8mg/kg concentration) was injected locally at the defect site whereas on the control side, saline was used. Mice were euthanized at 7, 14, and 28 days. MicroCT was used to quantify bone regeneration at the defect. Histological staining for ALP and TRAP was used to quantify osteoblast and osteoclast activity respectively. Immunohistochemical antibodies, β-catenin and CD34 were used to quantify active β-catenin levels and angiogenesis respectively. Sclerostin and GSK3β were also quantified and are both inhibitors of the wnt signaling pathway via degradation and inactivation of β-catenin. The boron group exhibited higher bone volume and trabecular thickness at the defect site by 28 days on microCT. ALP activity was significantly higher in boron group at 7 days whereas boron had no effect on TRAP activity. Additionally, CD34 staining revealed increased angiogenesis at 14 days in boron treated groups. β-catenin activity on immunohistochemistry was significantly higher in the boron group at 7 days, GSK3β was significantly higher in the boron group at 14 days and Sclerostin was significantly higher in the boron group at 28 days. Boron appears to increase osteoblast activity at the earlier phases of healing. The corresponding early increase in β-catenin along with ALP likely supports that boron increases osteoblast activity via the wnt/β-catenin pathway. Increased angiogenesis at 14 days could be a separate mechanism increasing bone formation independent of wnt/β-catenin activation. Neither GSK3β or Sclerostin levels correlated with β-catenin activity therefore boron likely increases β-catenin through a mechanism independent of both GSK3β and Sclerostin. The addition of this inexpensive and widely available ion could potentially become a non-invasive, cost-effective treatment modality to augment fracture healing and decrease non-union rates in high risk patients