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The Bone & Joint Journal
Vol. 104-B, Issue 1 | Pages 157 - 167
1 Jan 2022
Makaram NS Goudie EB Robinson CM

Aims. Open reduction and plate fixation (ORPF) for displaced proximal humerus fractures can achieve reliably good long-term outcomes. However, a minority of patients have persistent pain and stiffness after surgery and may benefit from open arthrolysis, subacromial decompression, and removal of metalwork (ADROM). The long-term results of ADROM remain unknown; we aimed to assess outcomes of patients undergoing this procedure for stiffness following ORPF, and assess predictors of poor outcome. Methods. Between 1998 and 2018, 424 consecutive patients were treated with primary ORPF for proximal humerus fracture. ADROM was offered to symptomatic patients with a healed fracture at six months postoperatively. Patients were followed up retrospectively with demographic data, fracture characteristics, and complications recorded. Active range of motion (aROM), Oxford Shoulder Score (OSS), and EuroQol five-dimension three-level questionnaire (EQ-5D-3L) were recorded preoperatively and postoperatively. Results. A total of 138 patients underwent ADROM; 111 patients were available for long-term follow-up at a mean of 10.9 years (range 1 to 20). Mean age was 50.8 years (18 to 75);79 (57.2%) were female. Mean time from primary ORPF to ADROM was 11.9 months (6 to 19). Five patients developed superficial wound infection; ten developed symptomatic osteonecrosis/post-traumatic arthrosis (ON/PTA); four underwent revision arthrolysis. Median OSS improved from 17 (interquartile range (IQR) 12.0 to 22.0) preoperatively to 40.0 (IQR 31.5 to 48.0) postoperatively, and 39.0 (IQR 31.5 to 46.5) at long-term follow-up (p < 0.001). Median EQ-5D-3L improved from 0.079 (IQR -0.057 to 0.215) to 0.691 (IQR 0.441 to 0.941) postoperatively, and 0.701 (IQR 0.570 to 0.832) at long-term follow-up (p < 0.001). We found that aROM improved in all planes (p < 0.001). Among the variables assessed on multivariable analysis, a manual occupation, worsening Charlson Comorbidity Index and increasing socioeconomic deprivation were most consistently predictive of worse patient-reported outcome scores. Patients who subsequently developed ON/PTA reported significantly worse one-year and late OSS. Conclusion. ADROM in patients with persistent symptomatic stiffness following ORPF can achieve excellent short- and long-term outcomes. More deprived patients, those in a manual occupation, and those with worsening comorbidities have worse outcomes following ADROM. Cite this article: Bone Joint J 2022;104-B(1):157–167


Bone & Joint Research
Vol. 6, Issue 4 | Pages 216 - 223
1 Apr 2017
Ang BFH Chen JY Yew AKS Chua SK Chou SM Chia SL Koh JSB Howe TS

Objectives. External fixators are the traditional fixation method of choice for contaminated open fractures. However, patient acceptance is low due to the high profile and therefore physical burden of the constructs. An externalised locking compression plate is a low profile alternative. However, the biomechanical differences have not been assessed. The objective of this study was to evaluate the axial and torsional stiffness of the externalised titanium locking compression plate (ET-LCP), the externalised stainless steel locking compression plate (ESS-LCP) and the unilateral external fixator (UEF). Methods. A fracture gap model was created to simulate comminuted mid-shaft tibia fractures using synthetic composite bones. Fifteen constructs were stabilised with ET-LCP, ESS-LCP or UEF (five constructs each). The constructs were loaded under both axial and torsional directions to determine construct stiffness. Results. The mean axial stiffness was very similar for UEF (528 N/mm) and ESS-LCP (525 N/mm), while it was slightly lower for ET-LCP (469 N/mm). One-way analysis of variance (ANOVA) testing in all three groups demonstrated no significant difference (F(2,12) = 2.057, p = 0.171). There was a significant difference in mean torsional stiffness between the UEF (0.512 Nm/degree), the ESS-LCP (0.686 Nm/degree) and the ET-LCP (0.639 Nm/degree), as determined by one-way ANOVA (F(2,12) = 6.204, p = 0.014). A Tukey post hoc test revealed that the torsional stiffness of the ESS-LCP was statistically higher than that of the UEF by 0.174 Nm/degree (p = 0.013). No catastrophic failures were observed. Conclusion. Using the LCP as an external fixator may provide a viable and attractive alternative to the traditional UEF as its lower profile makes it more acceptable to patients, while not compromising on axial and torsional stiffness. Cite this article: B. F. H. Ang, J. Y. Chen, A. K. S. Yew, S. K. Chua, S. M. Chou, S. L. Chia, J. S. B. Koh, T. S. Howe. Externalised locking compression plate as an alternative to the unilateral external fixator: a biomechanical comparative study of axial and torsional stiffness. Bone Joint Res 2017;6:216–223. DOI: 10.1302/2046-3758.64.2000470


The Journal of Bone & Joint Surgery British Volume
Vol. 86-B, Issue 8 | Pages 1158 - 1162
1 Nov 2004
Park MJ Kim HG Lee JY

Surgical release of the elbow was performed in 27 patients with post-traumatic stiffness at a mean of 14.5 months after the initial injury. The outcome was related to whether there had been heterotopic ossification, which had occurred in 18 elbows and to whether, if there had been a fracture, it had involved the articular surface, which had occurred in 13 elbows. The final range of movement and the ratio of desired gain in each group were compared at a mean follow-up period of 22.5 months (12 to 43). The arc of movement of the elbow improved in all patients after the operation. The mean final arc was 110° in those with heterotopic ossification and 86° in those without (p = 0.001). The ratios of desired gain were significantly higher in patients with heterotopic ossification (88.2% vs 54.9%; p < 0.001). There was no significant difference in relation to involvement of the articular surface. Careful assessment of the cause of stiffness is important in order to achieve a satisfactory result from surgery for post-traumatic stiffness of the elbow


The Journal of Bone & Joint Surgery British Volume
Vol. 83-B, Issue 4 | Pages 533 - 535
1 May 2001
Wade RH Moorcroft CI Thomas PBM

We have studied the progression of healing in 103 unstable fractures of the tibia. In 76 patients we removed the external fixator once the stiffness had reached 15 Nm/° in the sagittal plane. Deformity at the site of the fracture subsequently occurred in four patients. In a further 27, we measured stiffness in several planes and removed the fixator only when the stiffness reached 15 Nm/° in each. We found that stiffness in two orthogonal planes may differ widely (maximum difference 9.0 Nm/°, mean 4.1 Nm/°). There were no failures in the second group. We advocate that fracture stiffness be measured in two orthogonal planes when assessing tibial healing and suggest that values above 15 Nm/° in two planes give an indication that it is safe to remove the fixator


The Bone & Joint Journal
Vol. 97-B, Issue 10 | Pages 1417 - 1422
1 Oct 2015
Ferreira N Marais LC Aldous C

Tibial nonunion represents a spectrum of conditions which are challenging to treat, and optimal management remains unclear despite its high rate of incidence. We present 44 consecutive patients with 46 stiff tibial nonunions, treated with hexapod external fixators and distraction to achieve union and gradual deformity correction. There were 31 men and 13 women with a mean age of 35 years (18 to 68) and a mean follow-up of 12 months (6 to 40). No tibial osteotomies or bone graft procedures were performed. Bony union was achieved after the initial surgery in 41 (89.1%) tibias. Four persistent nonunions united after repeat treatment with closed hexapod distraction, resulting in bony union in 45 (97.8%) patients. The mean time to union was 23 weeks (11 to 49). Leg-length was restored to within 1 cm of the contralateral side in all tibias. Mechanical alignment was restored to within 5° of normal in 42 (91.3%) tibias. Closed distraction of stiff tibial nonunions can predictably lead to union without further surgery or bone graft. In addition to generating the required distraction to achieve union, hexapod circular external fixators can accurately correct concurrent deformities and limb-length discrepancies. Cite this article: Bone Joint J 2015;97-B:1417–22


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_5 | Pages 2 - 2
13 Mar 2023
Hoban K Yacoub L Bidwai R Sadiq Z Cairns D Jariwala A
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The COVID-19 pandemic presented a significant impact on orthopaedic surgical operating. This multi-centre study aimed to ascertain what factors contributed to delays to theatre in patients with shoulder and elbow trauma. A retrospective cohort study of 621 upper limb (shoulder and elbow) trauma patients between 16/03/2020 and 16/09/2021 (18-months) was extracted from trauma lists in NHS Tayside, Highland and Grampian and Picture Archiving and Communication Systems (PACS). Median patient age =51 years (range 2-98), 298 (48%) were male and 323 (52%) female. The commonest operation was olecranon open reduction internal fixation (ORIF) 106/621 cases (17.1%), followed by distal humerus ORIF − 63/621 (10.1%). Median time to surgery was 2 days (range 0-263). 281/621 (45.2%) of patients underwent surgical intervention within 0-1 days and 555/621 patients (89.9%) had an operation within 14 days of sustaining their injury. 66/621 (10.6%) patients waited >14 days for surgery. There were 325/621 (52.3%) patients with documented evidence of delay to surgery; of these 55.6% (181/325) were due to amendable causes. 66/325 (20.3%) of these patients suffered complications; the most common being post-operative stiffness in 48.6% of cases (n=32/66). To our knowledge, this is the first study to specifically explore effect of COVID-19 pandemic on upper limb trauma patients. We suggest delays to theatre may have contributed to higher rates of post-operative stiffness and require more physiotherapy during the rehabilitation phase. In future pandemic planning, we propose dedicated upper-limb trauma lists to prevent delays to theatre and optimise patients’ post-operative outcomes


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_6 | Pages 9 - 9
20 Mar 2023
Desai T Hoban K Ridley D Jariwala A
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Sub-acromial decompression surgery (SAD) has been widely used to treat shoulder impingement. Its validity has been questioned in multi-centric clinical trials and dissatisfaction rates can be high (35%). It is difficult to predict which patients will benefit operatively as research into predictive factors is limited. The study aim was to conduct a root-cause analysis of reasons for dissatisfaction in a cohort of operated patients. All patients with SAD dissatisfaction in the local Upper Limb database between 2015-19 (n=74/296) formed our study cohort. Patients were scored on Oxford shoulder score (OSS), QuickDASH score, EQ-5D-3L (TTO+VAS) at weeks 26 and 52 post-operatively. Patients' clinical history, radiographs, consultation and operative notes were reviewed. 28% of patients were dissatisfied with surgery. Mean age =52.3±13.4 years with equal gender distribution. 87% were operated arthroscopically. 67% were in physically demanding occupations. There was a significant increase in OSS and QuickDASH at weeks 26 and 52 post-operatively (p<0.05), similar improvement was not noted in VAS pain score. Pain followed by stiffness were the main contributors of dissatisfaction. Multiple implicating factors were noted, the most common being acromio-clavicular joint arthritis (25.7%), suggesting concomitant pathologies as an additional cause for patient dissatisfaction. This is the first study to evaluate reasons for dissatisfaction following SAD. We noted high rates (28%) of dissatisfaction and a predilection for those involved in physically demanding occupations. We recommend meticulous pre-operative workup to identify co-existing pathologies and appropriate pre-operative counselling to improve outcomes in selected patients needing SAD following failure of conservative management


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_18 | Pages 17 - 17
1 Dec 2023
Sharma N George A Hampton M Barnett A
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Introduction. Trochleoplasty is an effective surgical procedure for patients with severe trochlear dysplasia and recurrent patella instability. Previous work has suggested patients demonstrate early improvements in knee function and quality of life. However, concerns regarding longer term outcomes due to the development of stiffness and patellofemoral osteoarthritis remain a concern for these patients. Our aim was to assess mid-term patient-reported outcome and quality of life measures for trochleoplasty performed at a single centre for severe trochlear dysplasia. Methods. Retrospective review of 28 knees (23 patients) having undergone trochleoplasty for severe trochlear dysplasia were reviewed. Due to the non-parametric nature of the data, median and interquartile range (IQR) were determined for pre-operative and mid-term follow-up scores. Statistically significant differences between groups were assessed using paired Wilcoxon-signed rank test with statistical significance set at p<0.05. Data were analysed using a statistical software package (IBM® SPSS® Statistics 26.0). Results. Median time from surgery to follow-up for all patients in the series was 5.3 years (IQR 3.9 – 7.0 years). Median pre-operative Kujala score improved from 57.0 (IQR 45 – 66) to 96.3 (IQR 83 -100). Median pre-operative IKDC score improved from 42.6 (IQR 35.9 – 51.3) to 92.6 (IQR 71.6 – 98.7). Median EQ-5D score also improved from 0.691 (IQR 0.414 – 0.727) to 1.000 (IQR 0.8178 – 1.000). Improvement in Kujala scores, IKDC scores and EQ-5D were all statistically significant with p<0.001 in all domains. Discussion. Our data suggests patients experience significant improvements in knee function and quality of life following trochleoplasty surgery for severe dysplasia. We demonstrate an absolute improvement in scores at a mean of 5.3 years follow-up of 39.3 points for Kujala, 50 for IKDC and 0.309 for EQ-5D. Minimal clinically important differences (MCID) have been reported to be in the region of 10 for the Kujala score, 8.8–15.6 for IKDC and 0.085 for EQ-5D. Our data shows improvements which far exceed the published MCID, suggesting trochleoplasty confers a large treatment effect and patients benefiting from sustained improvements in knee function and overall quality of life at mid-term follow-up. Conclusion. Following trochleoplasty for severe trochlear dysplasia, patient reported outcomes demonstrate continued improvements in knee function and quality of life at mid-term (5-year) follow-up. There is a large absolute treatment effect which likely impacts on both physical and psychological wellbeing for these patients. Continued surveillance of patient reported outcomes in this clinically complex cohort is indicated


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_3 | Pages 12 - 12
1 Feb 2020
Giebaly D Vats A Marshall C Leach B Rooney B McConnachie A Jones B Blyth M
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MOXIMED KineSpring® Knee Implant System is an Orthopaedic device designed for younger or highly active patients with osteoarthritis. The device is placed under the skin, is attached to the tibia and femur, and contains springs which help limit some of the forces that are transmitted through the knee during activities such as walking or running and thereby relieve pain that may be experienced by patients with early arthritis of the knee. The aim of this study is to determine the long term safety and efficacy of the KineSpring knee implant system. This is a prospective case series involving two centres in Glasgow. 29 patients (mean age of 45.1 years and range 18-65 years) were recruited into the study between 2011 and 2016. The Primary outcome measure was Oxford knee score (OKS) at 2, 5 and 10 years post-operatively. Secondary outcome measures include device related complications and survival, patient reported functional outcome measures, patient satisfaction, pain levels and change in radiographic classification of osteoarthritis. At 2-year follow-up, 7 implants were removed (74.1% survival). Complications include deep infection, requiring removal in 1 patient, 2 implant failures requiring removal and one spring breakage. In comparison to pre-operative measures there was an improvement in the pain (3.58 vs. 5.20, p=0.02), stiffness (4.16 vs. 4.47, p=0.6) and OKS (32.4 vs. 36.9, p=0.03). The KineSpring improves overall pain, stiffness and functional outcome at 2 years following surgery, however there was a high rate of removal and further long-term follow up analysis is required regarding its effectiveness


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_8 | Pages 4 - 4
1 May 2018
Timms A Roskrow T Doyle H Edel P Fugazzotto S Goodier W Calder P
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Introduction. Muscle stiffness and joint contractures are common complications of limb lengthening. Authors have demonstrated less permanent soft tissue complications with intramedullary lengthening than external fixation. Our aim was to evaluate the joint response following intramedullary femoral lengthening and need for physiotherapy and alteration to rate/rhythm of lengthening. Method. A retrospective review of documentation for all femoral Precice nails in our centre inserted between 2012 and 2017. This involved 98 nails (68 antegrade, 30 retrograde) in 88 patients (59 males, 29 females) with a mean age of 32 years (range 12–69 yrs). We excluded cases where there was no documentation regarding Range of Movement (ROM). Bilateral lengthenings were recorded as separate cases. This left 50 antegrade, 16 retrograde cases with hip ROM data and 55 antegrade, 26 retrograde cases with Knee ROM data. Results. Hip. In the antegrade group 20 cases (39%) developed no stiffness throughout treatment. ROM decreased in 61% (n=30) of cases and the median length at which this occurred was 3cm. Where a retrograde nail was inserted 62.5% of cases (n=10) maintained normal range of motion. The median length at which ROM decreased was 3.25cm, this occurred in 6 cases (37.5%). . Knee. Where the antegrade nail was inserted, 22 cases (40%) did not develop stiffness. There was reduced ROM in 33 cases (60%), occurring at a median distance of 2cm. The median distance at which reduced ROM occurred with the retrograde nails was 1.5cm, this occurred in 23 cases (88.5%). 3 cases did not develop stiffness. All cases regained full ROM. Conclusion. Although there was no permanent loss, Joint Stiffness still occurs with intramedullary limb lengthening and there remains the need for regular physiotherapy. There are no data from other institutions for comparison. Rehabilitation guidelines and a proforma to accurately monitor patients ROM throughout treatment have been developed


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_8 | Pages 5 - 5
1 May 2018
Calder P Koroma P Wright J Goodier D Taylor S Blunn G Moazen M
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Aim. To quantify the micro-motion at the fracture gap in a tibial fracture model stabilised with an external fixator. Method. A surrogate model of a tibia and a cadaver leg were fractured and stabilised using a two-ring hexapod external fixator. They were tested initially under static loading and then subjected to vibration. Results. The overall stiffness of the cadaver leg was significantly higher than the surrogate model under static loading. This resulted in a significantly higher facture movement in the surrogate model. In the surrogate model there was no significant difference between the displacement applied via the vibrating platform and the fracture movement at the fracture gap. The fracture movement was however found to be statistically lower during vibration in the cadaver leg. Discussion. The significant difference in stiffness seen between the surrogate and cadaveric model is likely due to multiple factors such as the presence of soft tissues and fibula, including the biomechanical differences between the frame constructs. The fracture movement seen at 200N loading in the cadaveric leg was approximately 1mm which corresponds to partial weight bearing and a displacement shown to promote callus formation. During vibration however, the movements were far less suggesting that micromotion would be insufficient to promote healing. It may be proposed that soft tissues can alter the overall stiffness and fracture movement recorded in biomechanical studies investigating the effect of various devices or therapies


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_16 | Pages 12 - 12
1 Apr 2013
Tobita K Okazaki H Sato W Matsumoto T Bessho M Ohashi S Ohnishi I
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The most important issue in the assessment of fracture healing is to acquire information about the restoration of the mechanical integrity of bone. Echo tracking (ET) can noninvasively measure the displacement of a certain point on the bone surface under a load. Echo tracking has been used to assess the bone deformation angle of the fracture healing site. Although this method can be used to evaluate bending stiffness, previous studies have not validated the accuracy of bending stiffness. The purpose of the present study is to ensure the accuracy of bending stiffness as measured by ET. A four-point bending test of the gap-healing model in rabbit tibiae was performed to measure bending stiffness. Echo tracking probes were used to measure stiffness, and the results were compared with results of stiffness measurements performed using laser displacement gauges. The relationship between the stiffness measured by these two devices was completely linear, indicating that the ET method could precisely measure bone stiffness


Bone & Joint Open
Vol. 5, Issue 6 | Pages 457 - 463
2 Jun 2024
Coviello M Abate A Maccagnano G Ippolito F Nappi V Abbaticchio AM Caiaffa E Caiaffa V

Aims

Proximal femur fractures treatment can involve anterograde nailing with a single or double cephalic screw. An undesirable failure for this fixation is screw cut-out. In a single-screw nail, a tip-apex distance (TAD) greater than 25 mm has been associated with an increased risk of cut-out. The aim of the study was to examine the role of TAD as a risk factor in a cephalic double-screw nail.

Methods

A retrospective study was conducted on 112 patients treated for intertrochanteric femur fracture with a double proximal screw nail (Endovis BA2; EBA2) from January to September 2021. The analyzed variables were age, sex, BMI, comorbidities, fracture type, side, time of surgery, quality of reduction, pre-existing therapy with bisphosphonate for osteoporosis, screw placement in two different views, and TAD. The last follow-up was at 12 months. Logistic regression was used to study the potential factors of screw cut-out, and receiver operating characteristic curve to identify the threshold value.


Bone & Joint Open
Vol. 5, Issue 2 | Pages 147 - 153
19 Feb 2024
Hazra S Saha N Mallick SK Saraf A Kumar S Ghosh S Chandra M

Aims

Posterior column plating through the single anterior approach reduces the morbidity in acetabular fractures that require stabilization of both the columns. The aim of this study is to assess the effectiveness of posterior column plating through the anterior intrapelvic approach (AIP) in the management of acetabular fractures.

Methods

We retrospectively reviewed the data from R G Kar Medical College, Kolkata, India, from June 2018 to April 2023. Overall, there were 34 acetabulum fractures involving both columns managed by medial buttress plating of posterior column. The posterior column of the acetabular fracture was fixed through the AIP approach with buttress plate on medial surface of posterior column. Mean follow-up was 25 months (13 to 58). Accuracy of reduction and effectiveness of this technique were measured by assessing the Merle d’Aubigné score and Matta’s radiological grading at one year and at latest follow-up.


Bone & Joint Open
Vol. 4, Issue 8 | Pages 584 - 593
15 Aug 2023
Sainio H Rämö L Reito A Silvasti-Lundell M Lindahl J

Aims

Several previously identified patient-, injury-, and treatment-related factors are associated with the development of nonunion in distal femur fractures. However, the predictive value of these factors is not well defined. We aimed to assess the predictive ability of previously identified risk factors in the development of nonunion leading to secondary surgery in distal femur fractures.

Methods

We conducted a retrospective cohort study of adult patients with traumatic distal femur fracture treated with lateral locking plate between 2009 and 2018. The patients who underwent secondary surgery due to fracture healing problem or plate failure were considered having nonunion. Background knowledge of risk factors of distal femur fracture nonunion based on previous literature was used to form an initial set of variables. A logistic regression model was used with previously identified patient- and injury-related variables (age, sex, BMI, diabetes, smoking, periprosthetic fracture, open fracture, trauma energy, fracture zone length, fracture comminution, medial side comminution) in the first analysis and with treatment-related variables (different surgeon-controlled factors, e.g. plate length, screw placement, and proximal fixation) in the second analysis to predict the nonunion leading to secondary surgery in distal femur fractures.


The Bone & Joint Journal
Vol. 106-B, Issue 12 | Pages 1477 - 1484
1 Dec 2024
Wang Y Shen L Xie D Long H Chen H Wei J Zeng C Lei G

Aims

For displaced femoral neck fractures (FNFs) in geriatric patients, there remains uncertainty regarding the effect of total hip arthroplasty (THA) compared with hemiarthroplasty (HA) in the guidelines. We aimed to compare 90-day surgical readmission, in-hospital complications, and charges between THA and HA in these patients.

Methods

The Hospital Quality Monitoring System was queried from 1 January 2013 to 31 December 2019 for displaced FNFs in geriatric patients treated with THA or HA. After propensity score matching, which identified 33,849 paired patients, outcomes were compared between THA and HA using logistic and linear regression models.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_16 | Pages 58 - 58
1 Apr 2013
Tobita K Okazaki H Sato W Matsumoto T Bessho M Ohashi S Ohnishi I
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The most important issue in the assessment of fracture healing is to acquire information about the restoration of the mechanical integrity of bone. Many researchers have attempted to monitor stiffness either directly or indirectly for the purpose of assessing strength, as strength has been impossible to assess directly in clinical practice. The purpose of this study was thus to determine the relationship between bending stiffness and strength using mechanical testing at different times during the healing process. Unilateral, transverse, mid-tibial osteotomies with a 2-mm gap were performed in 28 rabbits. The osteotomy site was stabilized using a double-bar external fixator. The animals were divided into four groups (n=7/group/time point; 4, 6, 8 and 12 weeks). A series of images from micro-computed tomography of the gap was evaluated to detect the stage of fracture healing and a 4-point bending test was performed to measure stiffness and strength. Formation of cortex and medullary canal at the gap was seen in the 12-week group and would represent the remodeling stage. In addition, the relationship between stiffness and strength remained almost linear until at least 12 weeks. However, stiffness recovered much more rapidly than strength. Strength was not fully restored until the later stages of fracture healing. However, the current study demonstrated that stiffness could be monitored as a surrogate marker of strength until at least the remodeling stage


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_16 | Pages 14 - 14
1 Apr 2013
Penzkofer U Schmidt R Bachmaier S Augat P
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Background. The inherently high stiffness of locked plate constructs is increasingly recognized as a potential cause of deficient healing observed in patients with periarticular locked plating systems. The objective of this study is to perform a biomechanical comparison of distal femur locked plating systems. Methods. Biomechanical study using bone substitutes in a distal femur fracture model (OTA/AO 33-A3). Four different locked plate fixation systems were compared (AxSOS, LCP, PERI-LOC, POLYAX). Eight bone implant constructs of each plating system were evaluated in a multiple testing model to examine static failure, stiffness under static and cyclic loading and cyclic fatigue. Results. The implant systems made of titanium alloy (POLYAX & LCP) supported smaller torsional stiffness values under static loads and smaller axial stiffness values under cyclic loads compared with the implant systems made of stainless steel (PERI-LOC & AxSOS). All bone implant constructs reached the cyclic failure criterion of 10 degrees displacement at the fracture area within the third load level (>50000 cycles) except for the LCP which failed earlier. Conclusion. The tested four different locked plating systems differ significantly in terms of stiffness and load to failure. Two of the clinical available systems differed almost 100% in stiffness values. And one system differed almost 100% in fatigue strength. For clinical use, this knowledge is essential for the practicing orthopaedic surgeon


Orthopaedic Proceedings
Vol. 94-B, Issue SUPP_XV | Pages 20 - 20
1 Apr 2012
Bonner T Green S McMurty I
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Background. Locking internal fixation through a relatively small surgical dissection presents an innovative technique for managing distal tibial extra-articular fractures. The aim of this study is to evaluate the biomechanical properties of one locking internal fixation plate used to treat these injuries. Method. An AO/OTA43-A3 fracture was created in synthetic composite tibiae. Locking internal fixation was achieved with an anatomically pre-contoured medial distal tibial locking plate. Comparisons were made between different screw configurations in holes proximal to the fracture and monocortical versus bicortical fixation. Axial stiffness was measured using a universal materials testing machine. Finite element analysis (FEA) was used to model the elastic deformation of the constructs. Outcome measures were axial stiffness under physiological loading conditions and compression load to failure. Results. A trend towards reduced mean axial stiffness from the bicortical to the monocortical fixation constructs was observed. The physical model demonstrated no difference in measured mean axial stiffness between constructs with all screw holes filled and constructs with 2 screws in the holes closest and furthest from the fracture site. There was a 19% reduction in mean measured axial stiffness between constructs with all holes filled and in constructs with 2 screws in adjacent holes furthest from the fracture site (p<0.05). FEA predicted increased plate deflection and reduced construct axial stiffness with increasing distance of screw placement from the osteotomy site. Conclusion. Axial stiffness of distal tibial extra-articular metaphyseal fractures stabilized by locking internal fixation is dependent upon the configuration of the screw in the plate


Orthopaedic Proceedings
Vol. 102-B, Issue SUPP_3 | Pages 2 - 2
1 Feb 2020
Shields D Llopis-Hernandez V Jayawarna V Gonzales-Garcia C Marshall W Dalby M Salmeron-Sanchez M
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Osteoinductive bone substitutes are in their developmental infancy and a paucity of effective grafts options persists despite clinical demand. Bone mineral substitutes such as hydroxyapatite cause minimal biological activity when compared to osteoinductive systems present biological growth factors in order to drive bone regeneration. We have previously demonstrated the in-vitro efficacy of a bioengineered system at presenting growth factors at ultra low-doses. This study aimed to translate this growth factor delivery system towards a clinically applicable implant. Osteoinductive surfaces were engineered using plasma polymerisation of poly(ethyl acrylate) onto base materials followed by adsorption of fibronectin protein and subsequently growth factor (BMP-2). Biological activity following ethylene oxide (EO) sterilisation was evaluated using ELISAs targeted against BMP-2, cell differentiation studies and atomic force microscopy. Scaffolds were 3D printed using polycaprolactone/hydroxyapatite composites and mechanically tested using a linear compression models to calculate stress/strain. In-vivo analysis was performed using a critical defect model in 23 mice over an 8 week period. Bone formation was assessed using microCT and histological analysis. Finally, a computer modelling process was developed to convert patient CT images into surface models, then formatted into 3D-printable scaffolds to fill critical defects. Following EO sterilisation, there was no change in scaffold surface and persistent availability of growth factors. Scaffolds showed adequate porosity for cell migration with mechanical stiffness similar to cancellous bone. Finally, the in vivo murine model demonstrated rapid bone formation with evidence of trabecular remodelling in samples presenting growth factors compared to controls