P.S. Young

Component rotational alignment in unexplained painful primary total knee arthroplasty.

BACKGROUND Rotational malalignment of the components in total knee arthroplasty (TKA) can be a factor in poor outcomes but has yet to be defined. This study compares the rotational alignment of components in a cohort of 56 patients with unexplained pain following total knee arthroplasty with a matched control cohort of 56 patients with cemented Nex Gen Legacy posterior stabilised (LPS) flex fixed bearing TKA between March 2006 and May 2010. The aim of the study was to define an acceptable limit of rotation in total knee replacement. METHODS Rotational alignment was calculated using the Berger protocol with post operative computerised tomography scanning. The alignment parameters measured were tibial and femoral component rotations and the combined component rotations and the component rotational mismatch. RESULTS The two cohorts were demographically matched. Excessive internal rotation of the components was defined using the tenth percentile of rotations in the control cohort. Values of excessive internal rotation were 5.8° of the tibial component, 3.9° of the femoral component, 8.7° of combined rotation and 5.6° of the component mismatch. No significant difference was identified in excessive external rotation in any of the parameters. A significant difference in the mean rotations between the two cohorts was identified with internal rotation of the components in the painful cohort and external rotation on the control cohort. CONCLUSIONS We identified internal rotation malalignment of the tibial (p=0.0003) and femoral (p=0.014) components individually as well as the combined component rotation (p=0.0003) and component rotation mismatch (p=0.0001) to be a factor in pain following TKA. External rotation of any of the component parameters was not identified to be a factor in painful TKA. This study adds to the understanding of rotational alignment in TKA and suggests limits of internal rotation alignment associated with painful Nex Gen Legacy posterior stabilised (LPS) flex fixed bearing TKA. LEVEL OF EVIDENCE Level III.

THE EVOLVING ROLE OF COMPUTER ASSISTED NAVIGATION IN MUSCULOSKELETAL ONCOLOGY

We report our experience of using a computer navigation system to aid resection of malignant musculoskeletal tumours of the pelvis and limbs and, where appropriate, their subsequent reconstruction. We also highlight circumstances in which navigation should be used with caution. We resected a musculoskeletal tumour from 18 patients (15 male, three female, mean age of 30 years (13 to 75) using commercially available computer navigation software (Orthomap 3D) and assessed its impact on the accuracy of our surgery. Of nine pelvic tumours, three had a biological reconstruction with extracorporeal irradiation, four underwent endoprosthetic replacement (EPR) and two required no bony reconstruction. There were eight tumours of the bones of the limbs. Four diaphyseal tumours underwent biological reconstruction. Two patients with a sarcoma of the proximal femur and two with a sarcoma of the proximal humerus underwent extra-articular resection and, where appropriate, EPR. One soft-tissue sarcoma of the adductor compartment which involved the femur was resected and reconstructed using an EPR. Computer navigation was used to aid reconstruction in eight patients. Histological examination of the resected specimens revealed tumour-free margins in all patients. Post-operative radiographs and CT showed that the resection and reconstruction had been carried out as planned in all patients where navigation was used. In two patients, computer navigation had to be abandoned and the operation was completed under CT and radiological control. The use of computer navigation in musculoskeletal oncology allows accurate identification of the local anatomy and can define the extent of the tumour and proposed resection margins. Furthermore, it helps in reconstruction of limb length, rotation and overall alignment after resection of an appendicular tumour.

Serum lactate is a prognostic indicator in patients with hip fracture

Background and Purpose Serum lactate has been shown to be an indicator of adverse clinical outcomes in patients admitted secondary to general trauma or sepsis. We retrospectively investigated whether admission serum venous lactate can predict in-hospital mortality in patients with hip fractures. Method and Results Over a 38-month period the admission venous lactate of 807 patients with hip fractures was collated. Mean age was 82 years. The overall in-hospital mortality for this cohort was 9.4%. Mortality was not influenced by the fracture pattern or the type of surgery - be it internal fixation or arthroplasty (p = 0.7). A critical threshold of 3 mmol/L with respect to the influence of venous lactate level on mortality was identified. Mortality rate in those with a lactate level of less than 3 mmol/L was 8.6% and 14.2% for those whose level was 3 mmol/L or greater. A 1 mmol/L increase in venous lactate was associated with a 1.2 (1.02–1.41) increased risk of in-hospital mortality. Patients with a venous lactate of 3 mmol/L or higher had twice the odds of death in hospital compared to matched individuals. There was no statistically significant difference in ASA distribution between those with a lactate of less than or greater than 3 mmol/L. Conclusions Patients with an elevated venous lactate following hip trauma should be identified as being at increased risk of death and may benefit from targeted medical therapy.

Primary Osseous Tumors of the Hindfoot: Why the Delay in Diagnosis and Should We Be Concerned?

BackgroundBony tumors of the foot account for approximately 3% of all osseous tumors. Diagnosis is frequently delayed as a result of lack of clinician familiarity and as a result of their rarity. The reasons for the delays, however, are unclear.Questions/purposesWe therefore determined (1) how hindfoot tumors present and the specific reasons for delay in diagnosis; (2) whether the spectrum of disease varies between the talus and calcaneus; and (3) how these patients were treated.MethodsWe retrospectively reviewed the medical notes and imaging for all patients with 34 calcaneal and 23 talar tumors recorded in the Scottish Bone Tumour Registry. Demographics, presentation, investigation, histology, management, recurrence, and mortality were recorded.ResultsHindfoot tumors present with pain and often swelling around the heel (calcaneus) or ankle (talus), most often misdiagnosed as soft tissue injury. Calcaneal lesions were more likely to be malignant than talar lesions: 13 of 34 versus three of 23.ConclusionsClinicians should be aware that hindfoot tumors can be initially misdiagnosed as soft tissue injuries and suspicion of a tumor should be raised in the absence of trauma or persistent symptoms. Lesions affecting the calcaneus are more likely to be malignant. Early diagnosis and adjuvant therapy are important.Level of EvidenceLevel IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Primary bone tumours of the talus: The Scottish Bone Tumour Registry experience

BACKGROUND Primary bone tumours of the talus are rare and the existing literature is limited. The aim of this study was to investigate the epidemiology of primary bone tumours affecting this uncommon site and suggest a management protocol for these tumours. METHODS We retrospectively reviewed the Scottish Bone Tumour Register from January 1954 to May 2010 and included all primary bone tumours of the talus. RESULTS We identified only twenty three bone tumours over fifty six years highlighting the rarity of these tumours. There were twenty benign and three malignant tumours with a mean age of twenty eight years. A delay in presentation was common with a mean time from onset of symptoms to diagnosis of ten months. CONCLUSIONS Tumour types identified were consistent with previous literature. We identified cases of desmoplastic fibroma and intraosseous lipodystrophy described for the first time. We suggest an investigatory and treatment protocol for patients with a suspected primary bone tumour of the talus.

Conversion of a long distally fixed uncemented revision femoral stem to a proximally fixed implant following fatigue fracture

There has been increasing focus on bone conservation through proximal fixation in primary hip arthroplasty. However, the debate regarding fixation in revision arthroplasty and which factors influence implant choice remains less clear-cut. We report a case involving fatigue fracture of a long, distally well-fixed, uncemented revision stem. This was revised to a proximally fixed implant. This case highlights a number of issues when considering the choice of implant in hip revision surgery and raises the issue of bone conservation in revision surgery. We would suggest that in both primary and revision hip arthroplasty meticulous pre-operative consideration of the choice of implant should be undertaken, especially in the younger patient with higher expectations and functional demands.

Profunda Femoris Artery Pseudoaneurysm Complicating Compartment Syndrome after Blunt Trauma

In severe cases, acute compartment syndrome (ACS) maydevelop. It can be very difficult to differentiate significantcontusion or myositis from ACS, but early diagnosis is cru-cial to outcome and prevention of permanent loss offunction.Profunda femoris artery (PFA) pseudoaneurysm usuallydevelops after penetrating trauma, femoral fracture, orsurgical procedures and can have potentially devastatingconsequences, including extensive soft tissue injury, acutecompartment syndrome, neuropathy, arteriovenous fistu-lae, and rupture with severe hemorrhage.