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Bone & Joint Open
Vol. 2, Issue 5 | Pages 330 - 336
21 May 2021
Balakumar B Nandra RS Woffenden H Atkin B Mahmood A Cooper G Cooper J Hindle P

Aims

It is imperative to understand the risks of operating on urgent cases during the COVID-19 (SARS-Cov-2 virus) pandemic for clinical decision-making and medical resource planning. The primary aim was to determine the mortality risk and associated variables when operating on urgent cases during the COVID-19 pandemic. The secondary objective was to assess differences in the outcome of patients treated between sites treating COVID-19 and a separate surgical site.

Methods

The primary outcome measure was 30-day mortality. Secondary measures included complications of surgery, COVID-19 infection, and length of stay. Multiple variables were assessed for their contribution to the 30-day mortality. In total, 433 patients were included with a mean age of 65 years; 45% were male, and 90% were Caucasian.


Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_5 | Pages 25 - 25
1 Apr 2018
Mo A Berliner Z Porter D Grossman J Cooper J Hepinstall M Rodriguez J Scuderi G
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INTRO

Two-stage revision arthroplasty for PJI may make use of an antibiotic-loaded cement spacer (ACS), as successful long- term prevention of reinfection have been reported using this technique.[i] However, there is little data on systemic complications of high-dose antibiotic spacers. Acute kidney injury (AKI) is of clinical significance, as the drugs most commonly utilized, vancomycin and aminoglycosides, can be nephrotoxic. We intended to determine the incidence of AKI in patients that underwent staged revision arthroplasty with an ACS, as well as to identify potential predisposing risk factors for the disease.

METHODS

Local databases of six different orthopaedic surgeons were retrospectively reviewed for insertion of either a static or articulating antibiotic cement spacer by from 2007–2017. Dose of antibiotic powder implanted, as well as IV antibiotic used, was collected from operative records. Demographics, comorbidities, and preoperative and postoperative creatinine and hemoglobin values were recorded from the EHR. AKI was defined by a more than 50% rise in serum creatinine from preoperative baseline to at least 1.4 mg/dL, as described by Menge et al.[ii] Variables were analyzed for the primary outcome of AKI within the same hospital stay as insertion of the ACS. Categorical variables were analyzed with Chi-Square test, and continuous variables with univariate logistic regression.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_22 | Pages 59 - 59
1 Dec 2017
Frapwell C Duignan C Webb J Aiken S Cooper J Stoodley P Howlin R
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Aim

Bacterial biofilms play a key role in prosthetic infection (PI) pathogenesis. Establishment of the biofilm phenotype confers the bacteria with significant tolerance to systemic antibiotics and the host immune system meaning thorough debridement and prosthesis removal often remain the only possible course of treatment. Protection of the prosthesis and dead-space management may be achieved through the use of antibiotic loaded cements and beads to release high concentrations of antibiotics at the surgical site. The antibacterial and antibiofilm efficacy of these materials is poorly understood in the context of mixed species models, such as are often encountered clinically.

Methods

A P. aeruginosa and S. aureus in vitro co-culture biofilm model was grown using 1/5th BHI supplemented with 20 µM hemin. The ability of beads made from a synthetic calcium sulfate (CaSO4) loaded with vancomycin, tobramycin and vancomycin & tobramycin in combination to prevent biofilm formation and kill established co-culture biofilms were assessed using viable cell counts and confocal scanning laser microscopy (CSLM) over a 7 day time course. To assay for genetic changes to the individual species as a result of their presence together within a biofilm, mutation rates were measured using fluctuation analysis following growth as planktonic and biofilm cultures, alone or in co-culture. Mutants were determined based on their ability to grow on agar plates containing an inhibitory concentration of rifampicin. Mutation rates were calculated using the Ma-Sandri-Sarkar Maximum Likelihood Estimator and 94% confidence intervals compared for significance.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_9 | Pages 48 - 48
1 May 2017
Cooper J McKinnon J Walsh W Oliver R Rawlinson J Cristou C
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Background

Calcium sulfate and phosphate have a long clinical history of use as bone-void fillers (BVF) with established biocompatibility and resorption profiles. It has been widely reported that the addition of ‘impurity’ elements such as Silicon, Strontium and Zinc to calcium phosphate is advantageous, resulting in an improved bone healing response.

Methods

This study examined the in vivo response of two formulations of calcium sulfate, as 3mm diameter hemispherical beads, in critical sized defects created in cancellous bone of distal femur and proximal tibia (10mm diameter × 13mm depth) in adult sheep; beads prepared from recrystallised pharmaceutical grade calcium sulfate (RPCS, Stimulan, Biocomposites Ltd, UK) and a lower purity medical grade material containing 1% strontium (SrCS). The animals were sacrificed at 3, 6 and 12 weeks post implantation and the surgical sites analysed using microCT and decalcified histology.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_5 | Pages 90 - 90
1 Mar 2017
Porter D Bas M Cooper J Hepinstall M Rodriguez J
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BACKGROUND

This study aims to identify recent trends in discharge disposition following bilateral total knee arthroplasty (TKA) as well as factors that predispose patients to enter inpatient rehabilitation facilities (IRF) or skilled nursing facilities (SNF) versus home-rehabilitation (HR). The goal was to identify risk factors that predispose prolonged hospital stays and identify changes in management over time that may be responsible for decreased length of stay (LOS) and a HR program.

METHODS

A retrospective cohort study design was used to collect and analyze clinical and demographic data for 404 consecutive bilateral primary total knee arthroplasty (TKA) procedures. Patients who underwent elective primary bilateral total knee arthroplasty from 2011 to 2016 were identified from hospital records at a single institution. Clinical and demographic data including sex, age, and disposition were analyzed


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_5 | Pages 121 - 121
1 Mar 2017
Roc G Bas M Weiner L Hepinstall M Rodriguez J Cooper J
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Introduction

The incidence of periprosthetic fractures is increasing as the population ages. Wound complications and surgical site infections following surgery to treat periprosthetic fractures are a major source of patient morbidity and health care burden. This study evaluates the efficacy of closed-incision negative-pressure wound therapy (ciNPT) in decreasing wound complications and surgical site infections (SSIs) after periprosthetic fracture surgery about the hip and knee.

Methods

An IRB-approved retrospective quality improvement analysis of sixty-five consecutive periprosthetic fracture surgeries performed by four surgeons at a single institution in a fifteen-year period was performed. ciNPT was selectively used on patients in the last 20 months of the study period. Rates of wound complications, surgical site infections, and reoperation were compared with those of a sterile antimicrobial dressing (AMD).


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_5 | Pages 32 - 32
1 Mar 2017
Bas M Moya-Angeler J Cooper J Hepinstall M Scuderi G Rodriguez J
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Introduction

Stiffness after total knee arthroplasty (TKA) has been reported to occur due to component malpositioning and/or oversizing, improper femoral component (FC) flexion and tibial component (TC) slope, tight extension gap, inaccurate joint line placement, deficient posterior osteophyte resection, heterotopic ossification (HO), poor patellofemoral joint reconstruction, poor posterior condylar offset restoration, and/or posterior cruciate ligament (PCL) under-resection or retraction. However, the importance of these potential factors for stiffness are not well documented in the medical literature. The aim of this study was therefore to evaluate specific radiographic parameters in patients who had stiffness after primary TKA.

Material and Methods

An IRB-approved retrospective chart review was performed to identify patients that were revised due to stiffness after TKA. We defined stiffness as 15º or more of flexion contraction, less than 75º of flexion or a range of motion (ROM) of 90º with the chief complaint of limited ROM and pain. Patients with history of previous revisions and/or ORIF, infection, or isolated polyethylene exchange were excluded. Patients with a minimum of 1 year radiographic follow-up were included. Radiographic measurements were performed as described by the Knee Society TKA Roentgenographic Evaluation System (KSRES). Two blinded observers performed all measurements. Descriptive data is reported as mean (range). Inter-observer correlations were reported using Intraclass correlations coefficient (ICC).


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_5 | Pages 31 - 31
1 Mar 2017
Moya-Angeler J Bas M Cooper J Hepinstall M Rodriguez J Scuderi G
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Introduction

A stiff total knee arthroplasty (TKA) is an uncommon but disabling problem because it causes pain and limited function. Revision surgery has been reported as a satisfactory treatment option for stiffness with modest benefits. The aim of this study was to evaluate the results of revision surgery for the treatment of stiffness after TKA.

Methods

We defined stiffness as 15 degrees or more of flexion contracture or less than 75º of flexion or a range of motion of 90º or less presenting with a chief complain of limited range of motion and pain. We evaluated the results of forty-two revisions performed by one of four orthopedic surgeons due to stiffness after TKA. Patients with history of infection or isolated polyethylene insert exchange were excluded.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_4 | Pages 13 - 13
1 Feb 2017
Hawkins E Bas M Roc G Cooper J Rodriguez J
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Introduction

Iliopsoas impingement is a well described cause of groin pain after direct anterior total hip arthroplasty (THA). We proposed to evaluate the incidence, natural history and response to treatment of iliopsoas impingement after direct anterior total hip arthroplasty.

Methods

A retrospective chart review of 725 consecutive patients who underwent anterior approach total hip arthroplasty between 2009 and 2014 was conducted. All surgeries were performed by one of two surgeons. Patients were included if they underwent primary anterior approach THA and had a minimum of 2 years of follow up. Patients who had a posterior approach, revision surgery or had less than 2 years of follow up were excluded. Iliopsoas impingement was identified if patients reported groin pain at greater than 6 weeks of postoperative follow up and in association with pain with resisted seated hip flexion. The natural history and response to treatment was recorded for patients identified as having iliopsoas impingement.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_3 | Pages 79 - 79
1 Feb 2017
Cooper J Koenig J Hepinstall M Rodriguez J
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Introduction

Prosthetic replacement remains the treatment of choice for displaced femoral neck fractures in the elderly population, with recent literature demonstrating significant functional benefits of total hip arthroplasty (THA) over hemiarthroplasty. Yet the fracture population also has historically high rates of early postoperative instability when treated with THA. The direct anterior approach (DAA) may offer the potential to decrease the risk of postoperative instability in this high-risk population by maintaining posterior anatomic structures. The addition of intraoperative fluoroscopy can improve precision in component placement and overcome limitations on preoperative planning due to poor preoperative radiographs performed in the emergency setting.

Methods

We retrospectively reviewed clinical and radiographic outcomes of 113 consecutive patients with displaced femoral neck fractures treated by two surgeons over a five-year period. All underwent surgery via the DAA using fluoroscopic guidance, and were allowed immediate postoperative weight bearing without any hip precautions or restrictions. Charts were reviewed for relevant complications, while radiographs were reviewed for component positioning, sizing, and leg length discrepancy. Mean follow-up was 8.9 months.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_3 | Pages 78 - 78
1 Feb 2017
Cooper J Moya-Angeler J Hepinstall M Scuderi G Rodriguez J
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Introduction

Symptomatic instability following total knee arthroplasty (TKA) is a leading cause of early failure. Despite numerous reports on instability, standardized diagnostic and treatment protocols for these patients continue to remain unclear. Most reports recommend component revision as the preferred treatment, because of poor outcomes and high failure rates associated with isolated tibial polyethylene insert exchange (ITPIE). However, modern implant systems and standardized protocols may potentially change this teaching.

Methods

We performed an IRB-approved, retrospective review of 90 consecutive patients with minimum 2 years follow-up who underwent revision TKA for instability by one of four arthroplasty surgeons at a single institution. Mean age was 62.0 years (range, 41 to 83 years), and 73% of patients were women. Charts were reviewed for relevant preoperative clinical and physical exam findings, as well as pertinent intraoperative findings. Radiographs were analyzed for femoral and tibial component positioning. Pre- and post-operative Knee Society Scores (KSS) were calculated.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_3 | Pages 83 - 83
1 Feb 2017
Cowie R Aiken S Cooper J Jennings L
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Introduction

Calcium sulfate bone void fillers (CS-BVF) are increasingly being used for dead space management in infected arthroplasty revision surgery. The use of loose beads of CS-BVF close to the articulating surfaces of an implant means there is potential for them to migrate between the articulating surfaces acting as a third body particle. The aim of this study was to investigate the influence of CS-BVF on the third body wear of total knee replacements.

Methods

The influence of CS-BVF on wear was investigated using the commercially available CS-BVF ‘Stimulan’ (Biocomposites Ltd., UK) and posterior stabilised U2 total knee replacement system implants (United Orthopaedic Corp., Taiwan). The experimental wear simulation was performed using a six station ProSim electropneumatic knee simulator (Simulation Solutions, UK) running the Leeds intermediate kinematics input profile [1]. To investigate the damage that could be caused by the third body particles, 5cc of CS-BVF beads (excess) were placed on the tibial component of the implant, the simulator was run dry for 60 cycles before adding lubricant (25% bovine serum supplemented with 0.03% sodium azide) and running for an additional 115,000 cycles representative of the 6–8 weeks the CS-BVF are present in the body prior to their resorption. The surface topography of the cobalt chrome femorals was analysed using contacting profilometry to ascertain whether the third body particles of CS-BVF had damaged the surfaces. To investigate the influence of CS-BVF on the third body wear of the UHMWPE tibials, 3 million cycles (MC) of wear simulation was subsequently carried out. The wear of the UHMWPE tibials was assessed gravimetrically and the wear of implants tested with CS-BVF was compared to the wear against negative controls (initial Ra∼0.02µm) and positive controls (initial Ra ∼0.4µm) damaged with a diamond stylus. N=6 was completed for each condition, statistical analysis was carried out using ANOVA with significance taken at p<0.05.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_3 | Pages 35 - 35
1 Feb 2017
Bas M Rodriguez J Robinson J Deyer T Cooper J Hepinstall M Ranawat A
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Introduction

Total hip arthroplasty (THA) is a common operation. Different operative approaches have specific benefits and compromises. Soft tissue injury occurs in total hip arthroplasty. This prospective study objectively measured muscle volume changes after direct anterior and posterior approach surgeries.

Methods

Patients undergoing Direct Anterior Approach (DAA) and Posterior Approach (PA) THA were prospectively evaluated. 3 orthopaedic surgeons performed all surgeries. Muscle volumes of all major muscles around the hip were objectively measured using preoperative and 2 different postoperative follow-up MRIs. 2 independent measurers performed all radiographic volume measurements. Repeated-measures ANOVA was used to compare mean muscle volume changes over time. Student's t-test was used to compare muscle volumes between groups at specific time intervals.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_3 | Pages 80 - 80
1 Feb 2017
Cooper J Bas M Kamara E Seneviratne A Alexiades M Hepinstall M
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Introduction

Computer-assisted navigation is an established tool in hip and knee arthroplasty. This technology was introduced with the goals of greater precision in bone preparation and implant placement, potentially leading to improved clinical outcomes. Various navigation protocols exist, many of which require placement of temporary percutaneous pins in the operative field. Risks of pin placement have not been described.

Methods

We conducted a retrospective review of 352 consecutive patients undergoing elective hip and knee surgery using computer-assisted navigation between January 2013 and December 2015, all with a minimum follow-up of 90 days. Navigation pins were placed using a standardized protocol into the iliac crest for hip arthroplasty or into the femoral and tibial diaphysis for knee arthroplasty. Postoperatively, all patients were allowed to weight bear as tolerated. Patient records were reviewed for operative details and clinical outcomes. Outcome measures included any pin site complications including direct neurovascular damage, fracture through a pin site, and pin site infection.


Orthopaedic Proceedings
Vol. 98-B, Issue SUPP_1 | Pages 99 - 99
1 Jan 2016
Cowie R Carbone S Aiken S Cooper J Fisher J Jennings L
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Introduction

When third body particles originating from bone cement or bone void fillers become trapped between articulating surfaces of joint replacements, contact surfaces may be damaged leading to accelerated wear and premature failure of the implant. In this study, the damage to cobalt chrome counterfaces by third body particles from PMMA bone cement (GMV, DePuy) and various bone void fillers was investigated; then wear tests of UHMWPE were carried out against these surfaces.

Methods

Third body particles of polymerised GMV bone cement and the bone void fillers; OsteoSet (with tobramycin), Stimulan and Stimulan+ (with vancomycin and tobramycin) (provided by Biocomposites Ltd.) were trapped between an UHMWPE pin and a highly polished cobalt chrome plate. A load of 120N was applied to the pin and using an Instron materials testing machine, the plate was pulled beneath the pin to recreate third body damage [1]. The resulting surface topography of the plate was analysed using white light interferometry (Bruker NPFLEX). Pin on plate wear tests of GUR 1020 UHMWPE pins were carried out against the plates perpendicular to the direction of damage for 500,000 cycles in 25% bovine serum using a 6-station multi-axial reciprocating rig under conditions to replicate the kinematics in total knee replacement. Wear of the pins was determined by gravimetric analysis and results were compared to negative (highly polished) control plates and positive controls scratched with a diamond stylus (lip height 2µm). Statistical analysis was carried out using one-way ANOVA with significance taken at p<0.05.


Orthopaedic Proceedings
Vol. 97-B, Issue SUPP_15 | Pages 56 - 56
1 Dec 2015
Laycock P Cooper J Mckinnon J
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Daptomycin has a unique mechanism of action against Gram-positive bacteria. Daptomycin is only bactericidal in the presence of calcium ions. [1]

Kanellakopoulou et al [2] investigated elution of daptomycin from calcium sulfate. The results indicated above MIC elution concentrations out to 28 days. Experience reports that the ability for calcium sulfate to set hard when combined with daptomycin can be problematic.[3] This study aimed to investigate the combination of daptomycin with a synthetic recrystallised form of calcium sulfate and investigate zone of inhibition (ZOI) testing against susceptible organisms.

6mm hemispherical beads, were prepared using a commercially available calcium sulfate hemihydrate powder (CSH) – CaSO4 ·1/2H2O. [4] In order to combine daptomycin [5] with the CSH and enable it to set hard, 7mls of saline solution was added to 20g CSH powder and mixed for 80 seconds to initiate the setting reaction. Then 1g of daptomycin powder was added and mixed for a further 30 seconds. The resultant paste was applied to a bead mat and allowed to set.

Tryptone soya agar plates were seeded with 0.2ml of a 10e6 – 10e8 cfu/ml suspension of the relevant organism. The plates were incubated at 33 °C ± 2 °C for 30 minutes. The plates were then removed from the incubator and the beads placed on the surface. The plates were then incubated at 33 °C ± 2 °C for 24 hours before examination for the absence of growth as seen by a clear zone around the test sample.

Triplicate samples were tested against Staphylococcus epidermidis, Staphylococcus aureus, MRSA, VRE Enterococcus faecium and Propionibacterium acnes.

Repeat tests were carried out for beads that had been stored at 37 °C for 21 days to simulate in-vivo conditions.

Setting times for the CSH/daptomycin beads were approximately 20 minutes. ZOIs indicating efficacy were seen for all samples both ‘fresh’ and ‘incubated’ with MRSA and Propionibacterium acnes having the largest ZOIs at 31–33mm.

A mixing protocol was established to enable set beads to be formed with daptomycin loaded calcium sulfate. As assessed by ZOI testing, the eluted antibiotic maintained efficacy against susceptible pathogens. Results obtained in-vitro may not be indicative of in-vivo performance.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 37 - 37
1 Dec 2013
Silverton C Jacobs JJ Devitt J Cooper J
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Background

There are numerous concerns associated with femoral stems that feature a modular neck design, including the potential for corrosion, modular neck fracture, and adverse local tissue reactions. These stems have a higher-than-anticipated rate of failure in registry results, but large single-center cohort studies are lacking.

Methods

This is a retrospective, single-surgeon cohort of 133 hips in 119 patients implanted with a single dual-tapered titanium alloy stem with a modular titanium alloy neck (Profemur® Z; Wright Medical Technology, Arlington, TN). Several bearing surface combinations were used, including metal-on-polyethylene, ceramic-on-polyethylene, metal-on-metal, and ceramic-on-ceramic couples. Patients were evaluated at a mean of 4.5 years (range 2.0–9.0 years) with Harris Hip scores (HHS), radiographic analysis, and metal ion testing.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 503 - 503
1 Dec 2013
Robinson J Rathod P Stirton J Cooper J Ranawat A Rodriguez J
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The aim was to study the evolution of radiographic patterns of osteointegration of tapered wedge stems and determine if there is correlation with bony morphology and initial stem fit.

We reviewed primary total hip replacements performed by two surgeons using a single cementless tapered wedge design and that had a complete series of radiographs (defined as preoperative, 6 weeks, 1 year and 5 or more years).

Signs of bony remodeling were recorded at each Gruen zone. Calcar remodeling, changes in cortical thickness, evidence of subsidence and pedestal formation were recorded (Figure 1).

57 hips (50 patients) were available for analysis with a mean follow up of 5.03 years. Mean changes in cortical thickness were positive in zones 2(7.51) and 6(5.36) and negative in zones 1(−7.53) and 7(−13.51). Radiolucent lines were found in gruen zones 3,4(39%), and 5. Femoral neck cancellization was seen in zone 7 in 8 patients (14%) in year 1 and 36 (63%) by year 5.

Correlations were seen with proximal canal fill and radiolucent lines at zones 3 (0.278; p0.36) and 5 (0.258; p 0.05) and with distal canal fill and hypertrophy of the cortex in zone 3 (0.429; p0.001) and 5.

Cortical hypertrophy around the midstem, lack of radiolucent lines around the proximal stem and cancellization of the calcar are all radiographic patterns which occur routinely. A positive correlation with distal canal fill and hypertrophy of zones 3 and 5 was noted.

There was no significant correlation with preoperative boney morphology or initial stem fit proximally.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 483 - 483
1 Dec 2013
Porter D Urban R Jacobs JJ Rodriguez J Cooper J
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There is renewed concern surrounding the potential for corrosion at the modular head-neck junction to cause early failure in modern hip implants. Although taper corrosion involves a complex interplay of many factors, previous studies have correlated decreasing flexural rigidity of the femoral trunnion with an increased likelihood of corrosion at retrieval. A multicenter retrieval analysis of 85 modular femoral stems was performed to calculate the flexural rigidity of various femoral trunnions. Stems were implanted between 1991–2012 and retrieved between 2004–2012. There were 10 different taper designs from 16 manufacturers. Digital calipers were used to measure taper geometries by two independent observers. Mean flexural rigidity was 262 Nm2, however there was a wide range of values among the various stems spanning nearly an order of magnitude between the most flexible (80 Nm2) and most rigid (623 Nm2) trunnions, which was due in part to the taper geometry and in part to the material properties of the base alloy. There was a modest but significant negative correlation between flexural rigidity of the trunnion and release date of the stem. This wide variability in flexural rigidity may predispose particular stem designs to an increased risk of corrosion at the modular head-neck taper, and may in part explain why taper corrosion is being seen with increasing frequency in modern hip arthroplasty.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 273 - 273
1 Dec 2013
Cooper J Sanders S Berger R
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Introduction

Air travel and total joint arthroplasty are both established risk factors for development of venous thromboembolism (VTE); accordingly patients are typically counseled against flying in the early postoperative period. The basis for this recommendation may be unfounded, as the risk of VTE associated with flying in the early postoperative period has not been investigated.

Methods

This is a case-control study of 1465 consecutive unilateral total hip arthroplasties (THA) and total knee arthroplasties (TKA) performed by a single surgeon over an 18-month period. A multimodal regimen was used for VTE prophylaxis, consisting of early mobilization, mechanical prophylaxis, and chemoprophylaxis according to a risk-stratification model; 96% of patients received aspirin as the sole chemoprophylactic agent. The study population consisted of 220 patients (15.0%) who flew at a mean of 2.9 days after surgery. Patients who elected to fly were encouraged to wear anti-embolic stockings, perform frequent ankle-pump exercises, and move around at least every hour. Mean flight duration was 2.7 hours (range, 1.1 to 13.7 hours). This study population was compared to a control population of 1245 patients (85.0%) who did not fly during this time. Baseline characteristics were similar between the groups, with the exception that the group who flew tended to be older (65.5 vs. 59.5 years, p < 0.001) with a lower body-mass index (28.4 vs. 31.1 kg/m2, p < 0.001).


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 509 - 509
1 Dec 2013
Rathod P Rodriguez J Cooper J
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INTRODUCTION:

Short femoral stems are receiving increasing attention for less invasive total hip replacement (THR). The purpose of this study is to report our initial experience with a short modular femoral (SMF) stem at a minimum two-year follow up.

METHODS:

Twenty-six primary total hip arthroplasties (THAs) using the SMF stem were performed between August 2009 and January 2010. Patients were evaluated clinically with Harris Hip Score (HHS) and radiographically up to two years. Radiographs were analyzed to determine the degree of stem migration from its initial postoperative position. These parameters were compared to those of a cohort of 54 patients implanted with a monolithic tapered wedge stem from the same manufacturer over the same time period.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_34 | Pages 274 - 274
1 Dec 2013
Cooper J Urban R Deirmengian C Paprosky W Jacobs JJ
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Introduction

Taper corrosion at modular junctions can cause a spectrum of adverse local tissue reactions (ALTR) in the periprosthetic soft tissues in patients who have undergone total hip arthroplasty (THA). Because these reactions are usually painful, taper corrosion has become part of the differential diagnosis of hip pain following THA. However these destructive lesions may not always cause pain, and can occasionally result in other atypical presentations. The purpose of this study is to describe a cohort of patients presenting with late and recurrent instability following THA due to underlying ALTR and taper corrosion.

Methods

This is a multicenter retrospective case series of fourteen patients presenting with late instability secondary to ALTR and corrosion at the modular head-neck taper. The cohort included nine women and five men with a mean age of 66.8 years (range, 49 to 74). All patients had a metal (CoCr)-on-polyethylene bearing surface, but had a range of CoCr and Ti-alloy stem designs from three different manufacturers. Seven patients had 28 mm heads, while the rest had 32–40 mm heads. Patients experienced a mean of 3.4 dislocations (range, 2 to 6) at an average of 5.2 years (range, 0.4 to 17.0) following their index surgery. Although most reported some degree of discomfort around the hip, instability was the primary presenting symptom in all fourteen patients, and four were otherwise completely asymptomatic. Serum metal levels demonstrated a greater elevation of cobalt (mean 3.13 ng/mL) than chromium (mean 2.33 ng/mL). Preoperative infection workup including serum inflammatory markers and a hip aspiration documented the absence of sepsis.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_7 | Pages 15 - 15
1 Feb 2013
Evans S Ramasamy A Kendrew J Cooper J
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Aim/Purpose

Review our unique experience in the management of 29 consecutive casualties who survived open pelvic fractures following a blast mechanism.

Methods and Results

Retrospective study utilising a prospectively collected combat trauma registry. Records of UK Service Personnel sustaining open pelvic fractures from an explosion from Aug 2008 – Aug 2010 identified. Casualties who survived to be repatriated to the Royal Centre for Defence Medicine, University Hospital Birmingham were selected for further study. The median New Injury Severity Score (NISS) was 41. Mean blood requirement in the first 24 hours was 60.3 units. In addition to their orthopaedic injury, 6 (21%) had an associated vascular injury, 7(24%) had a bowel injury, 11 (38%) had a genital injury and 7(24%) had a bladder injury. 8 (28%) fractures were managed definitively with external fixation, and 7 (24%) fractures required internal fixation. Of those patients who underwent internal fixation, 5 (57%) required removal of metalwork for infection. Faecal diversion was performed on 9 (31%) casualties. Median length of stay was 70.5 days, and mean total operative time was 29.6 hours. At a mean 20.3 months follow-up, 24 (83%) were able to ambulate, and 26 (90%) had clinical and radiological evidence of pelvic ring stability.


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_1 | Pages 121 - 121
1 Jan 2013
Evans S Ramasamy A Cooper J Kendrew J
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The aim of this study is to review our unique experience in the management of 29 consecutive casualties who survived open pelvic fractures following a blast mechanism, in order to determine the injury pattern, clinical management and outcome of these devastating injuries.

All patients were serving soldiers who were injured whilst on operations in Afghanistan. The median New Injury Severity Score (NISS) was 41. Mean blood requirement in the 1st 24 hours was 60.3 units. In addition to their orthopaedic injury, 6 (21%) had an associated vascular injury, 7(24%) had a bowel injury, 11 (38%) had a genital injury and 7(24%) had a bladder injury. 8 (28%) fractures were managed definitively with external fixation, and 7 (24%) fractures required ORIF. Of those patients who underwent ORIF, 4 (57%) required removal of metalwork for infection. Faecal diversion was performed on 9 (31%) casualties. Median length of stay was 70.2 days, and mean total operative time was 29.6 hours. At a mean 20.3 months follow-up, 24 (83%) were able to ambulate, and 26 (90%) had clinical and radiological evidence of pelvic ring stability.

The “Global War on Terror” has resulted in incidents that were previously confined exclusively to conflict areas can now occur anywhere, and surgeons who are involved in trauma care may be required to manage similar injuries from terrorist attacks. Our study clearly demonstrates that the management of this injury pattern is extremely resource intensive with the need for significant multi-disciplinary input. Given the nature of the soft tissue injury, we would advocate an approach of minimal internal fixation in the management of these fractures. With the advent of emerging wound and faecal management techniques, we do not believe that faecal diversion is mandated in all cases.


The Journal of Bone & Joint Surgery British Volume
Vol. 94-B, Issue 6 | Pages 829 - 835
1 Jun 2012
Ramasamy A Evans S Kendrew JM Cooper J

The open blast fracture of the pelvis is considered to be the most severe injury within the spectrum of battlefield trauma. We report our experience of 29 consecutive patients who had sustained this injury in Afghanistan between 2008 and 2010. Their median new injury severity score (NISS) was 41 (8 to 75), and mean blood requirement in the first 24 hours was 60.3 units (0 to 224). In addition to their orthopaedic injury, six had an associated vascular injury, seven had a bowel injury, 11 had a genital injury and seven had a bladder injury. In all, eight fractures were managed definitively with external fixation and seven required internal fixation. Of those patients who underwent internal fixation, four required removal of metalwork for infection. Faecal diversion was performed in nine cases. The median length of hospital stay following emergency repatriation to the United Kingdom was 70.5 days (5 to 357) and the mean total operating time was 29.6 hours (5 to 187). At a mean follow-up of 20.3 months (13.2 to 29.9), 24 patients (82.8%) were able to walk and 26 (89.7%) had clinical and radiological evidence of stability of the pelvic ring.

As a result of the increase in terrorism, injuries that were previously confined exclusively to warfare can now occur anywhere, with civilian surgeons who are involved in trauma care potentially required to manage similar injuries. Our study demonstrates that the management of this injury pattern demands huge resources and significant multidisciplinary input. Given the nature of the soft-tissue injury, we would advocate external fixation as the preferred management of these fractures. With the advent of emerging wound and faecal management techniques, we do not believe that faecal diversion is necessary in all cases.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_IV | Pages 412 - 412
1 Nov 2011
Ward WG Cooper J
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The presence of an unremovable cemented tibial nail presents a unique challenge for limb salvage reconstructions utilizing a rotating hinge knee. All manufacturers’ designs except Link America incorporate a vertically-oriented rotational channel in the proximal tibia to provide the housing for a rotational axis stem. Such channel placement may be impossible in patients with pre-existing tibial hardware that obliterates the proximal tibial intramedullary canal. The Link America design utilizes a superiorly-projecting rotational stem that articulates with a housing located on the rotational yoke component; however it requires an intramedullary tibial stem for component stabilization. Thus all currently available rotating hinge knees require placement of a stem or a stem equivalent into the tibial intramedullary canal.

We describe a limb salvage case employing a Link America rotating hinge knee with a tibial component incorporating a custom hollow stem in a patient with an unremovable centralized, straight, cemented tibial nail. This reconstruction was required following an intra-articular fracture of a successfully incorporated massive proximal tibial osteoarticular allograft. The allograft had been implanted seven years previously following resection of a proximal tibia osteosarcoma.

This custom device allowed a relatively simple limb salvage reconstruction with good results and only a two day hospital stay.

This custom hollow-stemmed device allowed limb salvage in a situation that otherwise would have required either an amputation or resection of a healed tibial allograft that had successfully incorporated, replacing approximately 50% of the length of the tibia shaft. While rarely required, such an implant can allow a relatively simple and straight-forward functional salvage of an extremity in those patients whose only other choices for limb salvage include much more extensive bone resections and complex reconstructions. The potential for subsequent articular level failure should be considered whenever utilizing an osteoarticular allograft. A cemented, retrograde inserted, intramedullary nail can provide reliable internal fixation of such an allograft. If such fixation is selected, a straight intramedullary nail (as in this case) should be utilized, so that the intramedullary device is centered in the proximal tibia. This will allow for future revision to a total knee with a hollow stemmed tibial component should the need arise.


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_IV | Pages 470 - 470
1 Nov 2011
Ward W Cooper J Lippert D Kablawi R Sherertz R
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Perioperative infections can cause devastating results, especially in cases employing endoprostheses and/or allografts. To minimize bacterial contamination and thereby decrease infection rates, a series of experiments was performed to determine the role of several factors on intraoperative contamination.

In an initial pilot study, 102 surgical team members participating in clean orthopaedic cases were prospectively randomized to exchange or not exchange their outer pair of gloves one hour into the surgical procedures. Rodac plate cultures of the surgeon’s dominant gloved hand and of his or her gown sleeve were taken at baseline and again 15 minutes after potential glove exchange. The surgical gown type (reusable cloth versus disposable paper) utilized in each case was recorded. An unexpected overwhelming effect of gown type on bacterial contamination rates was detected, which overpowered any effect of glove exchange. The outer glove exchange experiment was then repeated with 251 prospectively randomized surgical team members, with all team members utilizing only disposable paper gowns. Otherwise the experimental protocol was the same. A final experiment was devised to test bacterial strike through of the two gown types. A standardized suspension (3 ml of coagulase negative staphylococcus containing 108 bacteria/ml) was applied to one side of the test materials and compressed with a 10 lb. weight. A rodac culture plate was applied to the opposite side of the material to determine bacterial strike through rates utilizing previously validated methodology.

The initial pilot experiment revealed a baseline sleeve culture positive rate of 41% with cloth gowns versus only 13% with disposable gowns (p=0.002, Students t-test). Cultures of the glove one hour and fifteen minutes into the operations revealed a 31% culture positive rate with reusable cloth gowns versus only 7% with disposable gowns (p=0.001), with a 4.38 x odds ratio. There was no statistically significant difference in the glove culture positive rate at one hour and fifteen minutes based on glove exchange (19% with glove retention vs. 10% following glove exchange p=0.19). There was no statistically significant difference in the culture positive rate between the two gown types when tested straight out of their sterile packaging (reusable gowns two positive cultures out of 50 cultures, disposable gowns zero positive cultures out of 50 cultures). On the second glove exchange experiment, surgeons exchanging gloves one hour into the case had a positive glove contamination rate of 13% compared to 23% in those retaining their original glove (p=0.04 Student’s t-test, odds ratio 0.51). The bacterial strike through study revealed that 22 of 25 cloth gowns allowed transmission of bacteria, whereas only 1 of 25 disposable paper gowns allowed transmission of bacteria (p=0.001, nonparametric sign rank test).

The choice of gown type had the greatest effect on the intraoperative culture positive rate of the surgeon’s dominant hand glove in our studies. Based on these results, at our institution, all orthopaedic surgeons now utilize only disposable paper gowns on all cases employing allograft or endoprosthesis implantation. We strongly recommend that only disposable paper gowns be utilized for any case with any orthopaedic implant materials and such gowns should be considered for all surgical cases. Exchange of the surgeon’s outer gloves prior to handling orthopaedic implant devices, especially if an hour of operating time has already elapsed, is also a recommended and prudent practice to diminish intraoperative contamination of the implant materials. The utilization of disposable drapes in addition to disposable gowns is also recommended due to the lower likelihood of bacterial strike through with currently available disposable synthetic materials. Following these recommended guidelines should help surgeons minimize the risk of intraoperative contamination and should thereby reduce the rate of infections.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_III | Pages 501 - 501
1 Aug 2008
Robb C Deans V Iqbal M Cooper J
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Introduction: The aim of our study was to assess any difference in outcome between non-surgical and surgical treatment of displaced calcaneal fractures.

Materials and Methods: We studied 40 patients between 2000 to 2005 with displaced calcaneal fractures. Patients with significant co-morbidities were excluded. Two groups of 14 patients, surgery vs. no surgery were compared for age, sex, length of follow-up, fracture type by Essex-Lopresti classification and SF-36 outcome score. The non-surgical group underwent treatment with rest, ice, compression, elevation and the surgical group underwent fixation with an AO calcaneal plate through an extended lateral approach.

Results: There was no statistically significant difference between the surgical and conservatively treated groups for age, sex, time since injury and fracture type according to Essex-Lopresti but a highly statistically significant difference in SF-36 outcomes between the two groups favouring surgically treated calcaneal fractures.

Summary: Displaced fractures of the calcaneum are a significant injury affecting patients general health. In the literature controversy exists as to whether operative or non-operative treatment is better for this type of fracture.

Conclusion: Although the numbers are small, our study favours operative intervention, if possible, for this controversial fracture.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_III | Pages 348 - 348
1 Sep 2005
Laurencin C Cooper J Sahota J Gorum J Carter J Ko F Doty S
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Introduction and Aims: There are more than 200,000 anterior cruciate ligament (ACL) ruptures each year in the United States. The replacements used for ACL repair do not fully recreate the ACL’s function and histological appearance. Therefore, a novel tissue-engineered ligament was designed and evaluated after ACL reconstruction in a rabbit model.

Method: Rabbits received tissue-engineered ligaments or tissue-engineered ligaments seeded with primary rabbit ACL cells. The tissue-engineered ligaments were composed of multifilament poly-L-lactide yarn (70 denier) fabricated into novel 24 yarn 3-D braids. Scaffolds were designed to be easily handled and fixed by the surgeon in ACL reconstructions using the suture over the button technique. A continuous scaffold design accommodated the flexibility of intra-articular loads and the rigours of the bone tunnels. The contralateral legs were used as controls. A key parameter for tissue ingrowth was scaffold porosity at 58 ± 9% and mode pore diameter of 183 ± 83 μm.

Results: Histological evaluations showed slow collagen tissue infiltration at the surface of the replacement at the four-week time point for both the tissue-engineered ligament and cell-seeded tissue-engineered ligament. At the 12-week time point, both replacements showed collagen ingrowth and remodelling across the entire implant occurred with a thin fibrous capsule. The cell-seeded tissue-engineered ligament demonstrated greater levels of mature collagen ingrowth and healing compared to the non-cell seeded tissue-engineered ligament. The initial tensile strength properties of the scaffold were 332 ± 20 N and 354 ± 68 MPa, which compared well to the rabbit ACL control (314 ± 66 N). The tensile properties of the tissue-engineered ligament and seeded tissue-engineered ligament at four weeks were 67% and 76%, respectively of control. The tensile properties of the biodegradable implant decreased with time for the tissue-engineered and cell seeded tissue-engineered ligament and by 12 weeks was 9% and 30% respectively, as compared to the rabbit ACL control. The 30% strength retention for the tissue-engineered ligament replacements at 12 weeks was greater than reported by others using poly(lactic acid) and polypropylene ligament augmentation devices (LAD) at 12 weeks, with values of 13% and 16% of control strength retention, respectively.

Conclusion: The results of this study demonstrate the promise of a novel cell seeded tissue-engineered ligament for anterior cruciate ligament regeneration.