Use of the Pixel Value Ratio Following Intramedullary Limb Lengthening: Uncomplicated Full Weight-bearing at Lower Threshold Values.

Aims: The pixel value ratio (PVR) can be used to assess regenerate consolidation after lengthening and guide advice for full weight-bearing (FWB). This study aimed to analyse the PVR in adults having femoral lengthening, the time to FWB and compare findings with the reported values in the literature. Materials and methods: A retrospective database review identified 100 eligible patients who underwent lengthening using the PRECICE nail (68 antegrade and 32 retrograde). The PVR was calculated in each cortex on plain radiographs at every visit. The ratio between the regenerate and an average from the adjacent normal bone was calculated and plotted against the clinical decision to allow FWB. Results: Eighty-seven patients (58 men and 29 women) were assessed; eleven had bilateral lengthening and two patients underwent lengthening twice. The median age was 30.5 years. The underlying cause of shortening was post-traumatic in 46%, with the remaining due to a wide variety of causes, including congenital 16%, syndromic 12% and other causes. The median lengthening achieved was 45 mm, at a median of 57.5 days. The PVR increased with each visit (p <0.0001). FWB was allowed at a median of 42 days after the last day of lengthening, with PVR values of 0.83, 0.84, 0.93 and 0.84 for the anterior, posterior, medial and lateral cortex noted, respectively (average 0.85). There were no implant failures, shortening or regenerate fractures. No differences were detected between antegrade and retrograde nails or with lengthening greater or less than 45 mm. One surgeon allowed earlier FWB at median 31 days with no nail failures. Conclusion: PVR is a valuable tool that quantifies regenerate maturity and provides objectivity in deciding when to allow FWB after intramedullary lengthening with the PRECICE nail. FWB was permitted at an earlier time point, corresponding with lower PVR values than have been reported in the literature and with no mechanical failure or regenerate deformation. How to cite this article: Elsheikh AA, Wright J, Stoddart MT, et al. Use of the Pixel Value Ratio Following Intramedullary Limb Lengthening: Uncomplicated Full Weight-bearing at Lower Threshold Values. Strategies Trauma Limb Reconstr 2022;17(1):14-18.

Development of a patient-reported outcome measure in limb reconstruction : a pilot study assessing face validity.

AIMS: Patients undergoing limb reconstruction surgery often face a challenging and lengthy process to complete their treatment journey. The majority of existing outcome measures do not adequately capture the patient-reported outcomes relevant to this patient group in a single measure. Following a previous systematic review, the Stanmore Limb Reconstruction Score (SLRS) was designed with the intent to address this need for an effective instrument to measure patient-reported outcomes in limb reconstruction patients. We aim to assess the face validity of this score in a pilot study. METHODS: The SLRS was designed following structured interviews with several groups including patients who have undergone limb reconstruction surgery, limb reconstruction surgeons, specialist nurses, and physiotherapists. This has subsequently undergone further adjustment for language and clarity. The score was then trialled on ten patients who had undergone limb reconstruction surgery, with subsequent structured questioning to understand the perceived suitability of the score. RESULTS: Ten patients completed the score and the subsequent structured interview. Considering the tool as a whole, 100% of respondents felt the score to be comprehensible, relevant, and comprehensive regarding the areas that were important to a patient undergoing limb reconstruction surgery. For individual questions, on a five-point Likert scale, importance/relevance was reported as a mean of 4.78 (4.3 to 5.0), with ability to understand rated as 4.92 (4.7 to 5.0) suggesting high levels of relevance and comprehension. Flesch-Kincaid reading grade level was calculated as 5.2 (10 to 11 years old). CONCLUSION: The current SLRS has been shown to have acceptable scores from a patient sample regarding relevance, comprehensibility, and comprehensiveness. This suggests face validity, however further testing required and is ongoing in a larger cohort of patients to determine the reliability, responsiveness, precision, and criterion validity of the score in this patient group. Cite this article: Bone Jt Open 2021;2(9):705-709.

Pediatric Lower Limb Lengthening Using the PRECICE Nail: Our Experience With 50 Cases.

BACKGROUND: Limb lengthening using intramedullary externally controlled motorized devices is becoming increasingly popular. There is limited literature regarding their use in the pediatric and adolescent population. This study reviews outcomes on 50 consecutive cases of intramedullary lower limb lengthening surgery in this population. METHODS: A retrospective review of all pediatric and adolescent patients treated in our institution by intramedullary lengthening for lower limb length discrepancy using the PRECICE and STRYDE intramedullary lengthening nails between 2013 and 2019. All patients were operated by a single surgeon. Data were prospectively recorded. We report on nail accuracy and reliability, consolidation index, time to full weight-bearing from completion of lengthening, joint range of movement, ASAMI bone and functional scores, presence of problems, obstacles and complications, and patient reported outcome measures (PROMS). RESULTS: Fifty cases (43 femoral and 7 tibial nails) were performed in 42 patients (20 males, 48% and 22 females, 52%). Six patients had bilateral lengthening and 2 patients had sequential lengthening. There were 28 antegrade femoral, 13 retrograde femoral and 5 tibia PRECICE nails, 2 tibial and 2 femoral PRECICE STRYDE nails. Mean age at surgery was 15 years old (12 to 17). Mean preoperative length discrepancy was 49 mm (20 to 90). Mean achieved lengthening was 46.5 mm (20 to 80). Mean percentage lengthening was 12.6% (5% to 25%). Nail accuracy was 96% and reliability 90%. Average distraction rate was 0.92 mm/d for femur and 0.64 mm/d for tibias. Consolidation index was 28 d/cm (18 to 43) and 39 d/cm (20 to 47), respectively. Time from completion of lengthening to independent full weight-bearing as observed in clinic was 45 days (21 to 70) and 34.2 days (23 to 50), respectively. ASAMI bone and functional scores were favorable and PROMS demonstrated high patient satisfaction levels. No significant complications were observed. CONCLUSIONS: We have demonstrated excellent clinical results and high patient satisfaction with intramedullary lengthening in a pediatric/adolescent population. We highly recommend thorough preoperative preparation, patient education, and a multidisciplinary approach. LEVEL OF EVIDENCE: Level IV.

Reducing the Risk of Ring Breakage in Taylor Spatial Frames: The Effect of Frame Configuration on Strain at the Half-ring Junction.

AIM: We have encountered four cases with Taylor spatial frames (TSF) (Smith & Nephew, Memphis, TN, USA) with breakage at the half-ring junction of the distal ring. This study examines the strain produced on different locations of the distal ring during loading and the effects on the strain of altering the frame construct. MATERIALS AND METHODS: We mounted two ring TSF constructs on tibia saw bone models. The proximal ring was the same in all constructs and consisted of a 2/3 180 mm ring attached with three wires. Construct 1 is reproducing the configuration of cases where failure was seen. The distal 155 mm ring is attached with three half pins. The half-ring junction is located in the midline. Construct 2 has a different half pin placement and an additional wire on the distal ring. Constructs 3 and 4 have the same half pin configuration to construct 1 but the distal ring is rotated 60° internally and externally, respectively. Strain gauges were attached to different locations and measurements recorded during loading. Statistical analysis was performed. RESULTS: Highest strain values were recorded at the half-ring junction of constructs 1 and 2 (>600 microstrains (µÎµ) in tension). Rotating the ring 60° internally significantly reduces the strain at the half-ring junction (<300 µÎµ) whilst external rotation by 60° further reduces the strain (<180 µÎµ). Ring strain is higher in areas close to half pin attachments. CONCLUSION: The highest strain is in the half-ring junction as the half rings are subjected to different loading modes. The thickness of the half-ring is halved and the second moment of area reduced further increasing breakage risk. Placing this junction close to the half pin-frame interface, as dictated by the anatomical safe zone further increases the strain. Rotating the distal ring 60° significantly reduces the strain at the half-ring junction. CLINICAL SIGNIFICANCE: Ring breakage is a rare but significant complication. This is the first study to address this potential mode of TSF failure. Insights and technical tips from this study can help reduce this. HOW TO CITE THIS ARTICLE: Iliadis AD, Bebja R, Wang K, et al. Reducing the Risk of Ring Breakage in Taylor Spatial Frames: The Effect of Frame Configuration on Strain at the Half-ring Junction. Strategies Trauma Limb Reconstr 2020;15(3):146-150.

Thromboprophylaxis in Intramedullary Limb Lengthening Surgery.

AIM: The use of intramedullary lengthening devices is becoming increasingly popular. There are limited data regarding the incidence of venous thromboembolism following intramedullary lengthening surgery and no reports or guidance for current practice on use of thromboprophylaxis. Following a case of post-operative deep vein thrombosis in our institution, we felt that it is important to assess best practice. We conducted a national survey to collect data that would describe current practice and help develop consensus for treatment. MATERIALS AND METHODS: We identified surgeons across the UK that perform adult intramedullary limb lengthening through the British Limb Reconstruction Society membership and a Precise Users database. Surgeons were contacted and asked to respond to an online survey. Responses to thromboprophylaxis regimes employed in their practice and cases of venous thromboembolism were collated. RESULTS: 24 out of 54 surgeons identified responded with a total of 454 cases of adult intramedullary lengthening (352 femoral and 102 tibial nails) performed over a five year period (January 2015-January 2020). Only one case of deep venous thrombosis (DVT) following femoral lengthening was reported. There is wide variability in practice both in terms of thromboprophylaxis risk assessment, choice of medications and duration of treatment. The vast majority of surgeons (85%) felt that there was insufficient evidence available to guide their practice. CONCLUSIONS: Intramedullary lengthening is a surgical treatment growing in popularity. There are limited data available to guide decision-making regarding aspects of treatment such as thromboprophylaxis. This is reflected in the wide variation in practice reported in this study. There are both a need and a desire to gather data that will allow us to come to a consensus and to guide safe practice. CLINICAL SIGNIFICANCE: Venous thromboembolism is a potential complication of lower limb lengthening surgery. We report on national incidence and current practices of thromboprophylaxis to allow for informed decision-making and help develop consensus for best practice. HOW TO CITE THIS ARTICLE: Iliadis AD, Timms A, Fugazzotto S, et al. Thromboprophylaxis in Intramedullary Limb Lengthening Surgery. Strategies Trauma Limb Reconstr 2020;15(3):151-156.

Assessment of material loss of retrieved magnetically controlled implants for limb lengthening.

PURPOSE: We aimed to understand wear from the telescopic component of PRECICE nails, which are used for distraction osteogenesis of the femur or tibia. We also aimed to identify any correlation between implant performance and patient factors. METHODS: This retrieval study involved 11 magnetically controlled intramedullary nails from nine patients who had achieved the targeted leg length. All the nails were assessed macroscopically and microscopically for wear. All implants were radiographed to assess the internal mechanism. A Talyrond 365 (Taylor Hobson, Leicester, UK) roundness measuring machine was used to generate three-dimensional surface maps of the telescopic components to allow for measurement of wear. RESULTS: Visual assessment of all the nails showed evidence of wear from the telescopic component. The radiographs revealed that all the nails had intact internal mechanism and no evidence of fractured pins. The roundness measuring machine showed that the quantity of wear was lowest in the latest design of the PRECICE nail. There was no significant correlation between wear and the two patient factors (duration of the lengthening phase, the time of implantation) included in this study. CONCLUSION: This study is the first to investigate the performance of the three different designs of the PRECICE system with a focus on wear. We found that the latest design had the best implant performance. We are confident of the continued success of the PRECICE system and reassure surgeons and patients that they are unlikely to encounter problems with the implant related to wear.

Stability at the half pin-frame interface on external fixation constructs.

A mechanical study investigating the use of two different methods (grub and bolt screws) to secure external fixation half pins to circular frames. A four part experiment: (1) Grub and bolt screws were used to secure half pins in Taylor Spatial frames. Loosening torques were measured using a calibrated torque wrench. (2) Using universal testing machine (UTM), axial loading was applied to establish thresholds for loosening in grub and bolt screw constructs. (3) We established the application torque to produce failure at the head-driver interface using these two methods. (4) Grub and bolt screw constructs were created controlling torque. Using UTM, axial loading was applied to establish thresholds for loosening. Statistical analysis was conducted using SPSS v20.0.0. (1) Higher torque is employed when bolt rather than grub screws is used to secure half pins on Rancho cubes (p < 0.05). (2) Loading threshold for loosening is higher in bolt screw constructs when the torque applied to secure the constructs is not controlled (p < 0.05). (3) Torque required for failure at the head-driver interface was 5.3 Nm for grub screws and 9.9 Nm for bolts. (4) Loading threshold for loosening is higher in grub screw constructs when the same torque was applied to secure them (p < 0.05). Bolt screws can be employed to secure the half pin-frame interface. They offer good stability and reduce failure at the head-driver interface. Further research is needed to determine the mechanical properties of such constructs in vivo.

Patterns of healing: a comparison of two proximal tibial osteotomy techniques.

Several low-energy osteotomy techniques are described in the literature, but there is limited evidence comparing them. Our study evaluates the patterns of regenerate formation using two different osteotomy techniques. Two cohorts of patients underwent osteotomy of the tibia using a Gigli saw (n = 15) or De Bastiani corticotomy (n = 12) technique. The patient radiographs were assessed by the two senior authors who were blinded to the osteotomy type. Regenerate quality was assessed along the anterior, posterior, medial and lateral cortices, graded 1-5 from absent to full consolidation over time. The time to 3 cortices healed/regenerate length was calculated. The time to consolidation of the anterior, posterior, medial and lateral cortices was compared. The mean 3 cortices index in the Gigli group was 2.0 months/cm and in the De Bastiani group 1.8 months/cm. This was not a significant difference. In both groups, anterior bone formation was slower, and anterior cortical deficiency with a scalloped appearance was seen in 25 % of cases overall with no statistically significant difference between the two groups. Both Gigli saw and De Bastiani corticotomy techniques result in good bone formation following distraction osteogenesis. The anterior tibial cortex consolidates more slowly than the other cortices in both groups. This is likely due to deficient soft tissue cover and direct periosteal damage at time of osteotomy.

The incidence of deep vein thrombosis and pulmonary embolism with the elective use of external fixators.

Little evidence exists about the incidence of deep vein thrombosis (DVT) and pulmonary embolism (PE) with the use of external fixators. We investigated this in a cohort of 207 consecutive patients undergoing 258 elective frame applications by case note review. Case notes were obtained for 84 % of the sample population. The type of surgery, demographic data, thromboembolic risk factors and the incidence of DVT/PE were recorded. One patient experienced DVT (0.39 %) and one a PE (0.39 %). Both were of high risk and had received mechanical and chemical thromboprophylaxis during their inpatient stay. These complications were identified at least 3 months post-operatively. These findings help to more accurately counsel patients undergoing elective frame surgery on the risks of DVT/PE and also contribute to the discussion between surgeons about whether or not extended course chemical thromboprophylaxis would be of overall benefit.

Different methods of creatinine measurement significantly affect MELD scores.

Bilirubin (Bil) interferes with creatinine (Cr) measurement. Different laboratory methods are used to overcome this problem. Model for end-stage liver disease (MELD) scoring incorporates Cr and is used to prioritize patients for liver transplantation. Thus, MELD scores may vary with different Cr measurements influencing patients' priority. Our aim was to evaluate 4 different Cr assays (O'Leary modified Jaffe [mJCr], compensated [rate blanked] kinetic Jaffe [cJCr], enzymatic [ECr], and standard kinetic Jaffe [JCr]) in patients with abnormal liver function tests and assess changes in MELD score. A total of 403 consecutive samples from 158 patients' Cr assays were evaluated.. Bland-Altman plots and MELD scores were also evaluated for each assay. Agreement was found to be poor among all Cr assays. Increased variability in Cr occurred with increasing Bil concentrations: Bil <100 micromol/L or=400micromol/L or=3-point difference in 78%. When MELD was >or=25 (mJCr as reference; mean, 30.5 points), MELD variation was greatest: mean, 28 (MELD cJCr), 27.5 (MELD ECr), and 28.4 (MELD JCr) (P < 0.001). In conclusion, there is poor agreement among different assays for Cr. As Bil concentration rises, there is greater variability in each creatinine measurements and thus greater variability in MELD scores that, this affect prioritization for liver transplantation.

Ilizarov wire tensioning and holding methods: a biomechanical study.

AIM: To investigate and compare two specific methods of Ilizarov wire tensioning and hold. METHOD: This study utilised the vertical Hounsfield test machine H25KS, a stress/strain device with a load-cell linked to a computer program. Firstly, the department's present mechanical tensioners were assessed. Secondly, the method of twisting the three designs of wire holding bolts to achieve wire tension, as described by Ilizarov, was assessed. These bolts are described as "cannulated", "slotted" and "Russian" (which are hexagonal headed with a slot down one side). RESULTS: The mechanical tensioners were found to be accurate, if inefficient, with a maximum producible tension of 1330N. The most effective bolts for creation of tension were the Russian, which produced mean wire tensions of 785N at 45 degrees; 1200N at 90 degrees; 1695N at 135 degrees. The cannulated and slotted bolts regularly broke the wires at 90 degrees twist. CONCLUSION: The findings demonstrated two effective methods. The present tensioners were found to be inefficient when compared to the simple twisting of the wire holding bolts, which created equivalent tensions with ease and are capable of producing greater wire tensions. The Russian bolts are recommended for use when wire tension is created by bolt twisting.

The biomechanics of wire fixation in the Ilizarov system.

The purpose of this study was to establish the optimal fixation of tensioned wires to the frame construct in the Ilizarov system. The usual torque to which the fixation bolts were tightened in clinical practice was established by serial testing of orthopaedic surgeons' work in our unit. The force required to produce wire slippage from the different types of wire fixation bolts, tightened to a predetermined torque, was measured using a testing rig. Analysis of the usual torque to which bolts were tightened in clinical practice, revealed values in the range of 5-10Nm. The load required to cause failure of the tensioned wire varied considerably depending on the bolt configuration used and the applied torque. In clinical practice, wires are tensioned using a dynamometer to a variety of loads, depending on the clinical situation, up to 1275N. In applying multiple wires across a single ring, as is normal practice, these loads may be increased still further. The total load transmitted by single wires in weightbearing may be up to 2000N. Utilising the results of our work has enabled us to choose, where practically possible, the optimal bolt configuration for wire fixation. In addition, this work has revealed that in order to withstand the loads seen in clinical practice, wire fixation bolts should be tightened to at least 10Nm. Post-operatively, we now tighten all our wire fixation bolts to 10Nm, using a calibrated torque wrench.