Total ankle replacement : Clinical, radiological, and biochemical assessment with special reference to osteolysis

End-stage ankle arthritis may be managed surgically with either ankle fusion or total ankle replacement (TAR). The results of total ankle replacement have improved over the recent decades, but challenges remain. Peri-implant osteolysis has been major problem, as it compromises the stability of the implant components and can lead to aseptic loosening and implant failure. For this retrospective study, 164 ankles (34 Scandinavian Total Ankle Replacement (STAR) and 130 Ankle Evolutive System (AES)) operated on in single institution during 1997–2008 were followed clinically and radiologically. Histological samples were collected from ankles revised due to periprosthetic osteolysis. Analysis from the data covering the years 1997–2006 of the Finnish Arthroplasty Registry was conducted. The peri-implant osteolysis was quite common in the AES total ankle implants: 70% of the ankles exhibited osteolysis at the latest follow-up. Dual-coating of the implant was associated with a 3.1-fold risk of osteolysis and of significantly earlier development of osteolysis compared to single-coating. Histology revealed a foreign-body reaction characterized by extensive soft and bone tissue necrosis. RANK/RANKL-mediated osteoclast and multinuclear foreign body giant cells contributed to peri-implant osteolysis, and there was increased expression of danger signals in the peri-implant tissues, suggesting an auto-inflammation mechanism behind osteolysis. The annual incidence of TAR according to the Finnish Arthroplasty Registry was 1.5 per 105 inhabitants and overall implant survival was 83% at 5 years when any revision was the end point. The most common reasons for revision were aseptic loosening (39%) and instability (39%). In the registry study, there was no difference in the survival rates between the STAR and AES designs, nor was there any association between age, gender, diagnosis, or hospital volume and TAR survival. The survival of the STAR implant was satisfactory, 93.8% (95% CI 77.5% to 98.4%) at 5 years, and 87.2% (95% CI 69.4% to 95.0%) at 10 and 15 years. There was no statistically significant association between implant survival and patient age, gender, BMI, or diagnosis. The overall rate of revisions was 44%, which includes all postoperative revisions for osteolysis, component and insert exchanges, and conversions to arthrodesis. The survival of the AES implant was strongly affected by osteolysis and malalignment, and inferior compared to previously published results. The 5-year survival was 87.3% (95% CI 80.0% to 92.0%), and the 10-year survival 74.9% (95% CI 65.4% to 82.2%). Postoperative alignment of ≥10º of varus predicted a poorer outcome and was statistically significant for implant survival (p=0.0005). The revision rate for all revisions was 57% including all postoperative revisions for osteolysis, component exchanges, and conversions to arthrodesis. Osteolysis was the main reason for revisions and failure. The survival of the STAR total ankle replacement was satisfactory in the long-term, but the results of the AES total ankle implants were strongly influenced by aggressive and early-emerging osteolysis. Future studies should focus on examining the mechanism behind the osteolytic process in TAR to avoid similar problems for implant development in the future.Nilkan tekonivel: Kliininen, radiologinen ja biokemiallinen seuranta Ylemmän nilkkanivelen loppuvaiheen nivelrikkoa voidaan hoitaa nilkan luudutus- tai tekonivelleikkauksella. Viime parinkymmenen vuoden aikana nilkan tekonivelleikkaus tuhoutuneen ylemmän nilkkanivelen hoidossa on yleistynyt. Hankalin nilkan tekonivelen komplikaatio on viime vuosien aikana ollut osteolyysi eli luun liukeneminen tekonivelen ympäriltä, joka saattaa johtaa tekonivelen irtoamiseen. Tässä takautuvassa tutkimuksessa analysoitiin yhdessä sairaalassa laitetun 164 nilkan tekonivelen (34 Scandinavian Total Ankle Replacement (STAR) ja 130 Ankle Evolutive System (AES)) kliiniset ja radiologiset seurantatulokset. Kudosnäytteet saatiin nilkoista, jotka oli jouduttu uusintaleikkaamaan osteolyysin vuoksi. Lisäksi analysoitiin Suomen Endoproteesirekisterin dataa ajalta 1997–2006 koskien nilkan tekoniveliä. Osteolyysin määrä AES-nilkan tekonivelissä oli korkea, 70 % nilkoista viimeksi tehdyn analyysin mukaan. AES-tekonivelen kaksoispinnoite aiheutti yli kolminkertaisen riskin osteolyysin kehittymiselle sekä merkitsevästi aikaisemmin ilmaantuvaa osteolyysiä yksinkertaiseen pinnoitteeseen verrattuna. Mikroskooppitutkimuksessa todettiin vierasesinereaktio ja runsaasti kudoskuoliota. Suomen Endoproteesirekisteriin perustuvassa tutkimuksessa nilkan tekonivelen vuosittainen ilmaantuvuus oli 1,5 tapausta 100.000 asukasta kohti. Nilkkaproteesin kokonaispysyvyys oli 83 % 5 vuoden aikana, kun päätetapahtumana oli mikä tahansa uusintaleikkaus. Uusintaleikkauksen yleisimmät syyt olivat aseptinen irtoaminen (39 %) ja epävakaus (39 %). Rekisteritutkimuksen mukaan implanttimallilla, potilaan iällä, sukupuolella, diagnoosilla tai sairaalan leikkausvolyymilla ei ollut yhteyttä implantin pysyvyyteen. STAR-nilkan tekonivelen pysyvyyden todettiin olevan erittäin hyvä, 93.8 % viiden vuoden ja 87,2 % kymmenen ja viidentoista vuoden aikana. Potilan iällä, sukupuolella, painoindeksillä tai diagnoosilla ei todettu yhteyttä tekonivelen pysyvyyteen. Uusintaleikkausten määrä oli 44 % sisältäen kaikki uusintaleikkaukset osteolyysin vuoksi, komponenttien vaihdot ja tekonivelen vaihdot luudutukseen. AES-nilkan tekonivelen pysyvyys oli huonoa, ja siihen vaikuttivat sekä runsas osteolyysin määrä että nilkan virheasento. Viiden vuoden pysyvyys oli 87.3 % ja kymmenen vuoden 74.9 %. Leikkauksen jälkeisen nilkan virhelinjauksen todettiin ennustavan tilastollisesti merkitsevästi huonompaa tulosta. Uusintaleikkausten määrä oli 57 % sisältäen kaikki uusintaleikkaukset osteolyysin vuoksi, komponenttien vaihdot ja tekonivelen vaihdot luudutukseen. Osteolyysi aiheutti suurimman osan uusintaleikkauksista ja epäonnistumisista. STAR-tekonivelen pysyvyys oli hyvä pitkällä aikavälillä, mutta AES-tekonivelen tuloksia huononsi merkitsevästi erittäin aikaisessa vaiheessa ilmaantunut aggressiivinen osteolyysi. Tulevaisuudessa tutkimusten tulisi keskittyä selvittämään tarkemmin osteolyysin mekanismeja, jotta vastaavat ongelmat voitaisiin jatkossa välttää tekonivelien kehitystyössä.Siirretty Doriast

Biomechanical Investigations of Medial Opening Wedge High Tibial Osteotomy: Gait Analysis, Materials Testing and Dynamic Radiography

This thesis aimed to develop and assess biomechanical methods to assist in the evaluation of medial opening wedge high tibial osteotomy (HTO). Five studies using diverse methods were performed, including three-dimensional (3D) gait analysis, materials testing of HTO fixation plates, and dynamic radiography in patients after surgery. Study 1 compared external knee joint moments during walking before and after varus or valgus producing osteotomy in patients with lateral or medial compartment osteoarthritis, and in healthy participants. The results highlighted the importance of alignment on gait biomechanics with changes in frontal plane angular impulse highly correlated to changes in mechanical axis. Study 2 compared the 3D external knee moments before and after medial opening wedge HTO during level walking and during stair ascent. Long-term changes in knee moments after HTO were observed during both activities, with decreases in the peak knee adduction and internal rotation moments. Study 3 developed and tested a multi-axis fixation jig placed within a materials testing machine for assessing HTO fixation plates in a manner more representative of walking. The need to incorporate gait data into materials testing studies was highlighted, showing the importance of including a frontal plane moment during testing. Study 4 used this multi-axis fixation jig to compare flat to toothed HTO fixation plates under cyclic loading conditions. Preliminary results suggested little difference in the load at failure between the plates; however, the potential for the tooth to increase micro-motion across the osteotomy site and strain on the lateral cortical hinge should be a focus of future testing. Study 5 was a proof-of-concept study to test dynamic single-plane flat-panel (FP) radiography for use in detecting in-vivo micro-motion after medial opening wedge HTO. Preliminary results suggested dynamic FP radiography has the potential to assess fixation stability; however, results also suggested modifications in the registration algorithms may be required to increase confidence in distinguishing true motion from registration error. Overall, this thesis demonstrates that a mix of biomechanical methods can be used to advance medial opening wedge HTO, with particular focus on informing future methods of investigation to improve HTO fixation designs

Evaluation on the Outcome of Management of Infected Non Union and Gap Non Union Fracture of Long Bones by Ilizarov Method

INTRODUCTION: Management of infected non-union and gap non-union fracture of long bones is a great challenge to orthopaedic surgeons. Infected non-union of fractures is not a single problem and it is associated with multiple problems like infections, bone defects, limb length discrepancies, deformities and soft tissue problems like scaring, discharging sinuses, etc. Duration of treatment and cost creates a huge burden to the patient as well as treating institution. Ilizarov address all the problems simultaneously. Distraction osteogenesis following corticotomy helps in filling the bone defects, eradicating the infection and promote fracture healing. MATERIALS AND METHODS: This Prospective study was conducted at The department of Orthopaedics, Stanley medical college, Chennai, Tamil Nadu during the period August 2015 to July 2016. In our study includes 20 cases with 18 males and 2 females admitted with infected non-union fracture of long bones, gap non-union fracture of long bones due to various causes was treated by Ilizarov ring fixation method and were studied for the functional outcome, complications and fracture union. The results were evaluated using the criteria laid down by The Association for The Study and Application of the Methods of Ilizarov (ASAMI) Scoring system. RESULTS: Bone healing was excellent in 75% of cases, good in 20%, fair in 5% and none of cases have poor results. Functional results were excellent in 40% and good in 55% , fair in 5% of cases and none of cases show poor results. Limb length discrepancies and joint stiffness are the common complications. CONCLUSIONS: The goal in treatment of infected non-union and gap non-union is to have a well aligned, painless, healed and functional limb. Ilizarov ring fixation is the better option in treatment of infected non-union and gap non-union. Considering the complexity of problems , it is the treatment of choice as it address the problems associated with infected non-union and gap non-union of fracture. Sound patient selection with realistic treatment goals is the key for successful management

Surgical site infection following major lower limb amputation : analysing the clinical effectiveness of antibiotic prophylaxis duration and skin preparation

Background: Major LLA remains a common operation in the United Kingdom with ⁓5000 procedures performed yearly. Amputations are described as ‘clean surgery’ and SSIs in this patient cohort have been previously under-reported. The true incidence lies between 13-35% and is associated with patient mortality, morbidity and implications on health economics. Previous work done in this thesis has demonstrated lack of consensus in clinical practice regarding perioperative antibiotic prophylaxis, and lack of high quality studies to formulate and sustain a common practice across the UK.Methods: A single centre RCT was designed to which a total of 161 patients were recruited and randomised to receive either a 5-day or a 24-hour prophylactic antibiotic course. Within the groups further allocation to skin preparation (alcoholic chlorhexidine Vs. alcoholic povidone iodine) was performed by stratification.Results: A total of 153 patients were included in the final analysis. Groups were well matched for comorbidities and demographics. The use of a 5-day course was associated with a statistically significant lower incidence of SSI(n=9, 11.5%) when compared to the 24-hour group (n=27, 36%) (P<0.001) and lower incidence of IWH(n=20, 25.6% Vs. n=40, 53.3% respectively) (P<0.001). History of diabetes, smoking, and transmetatarsal amputations performed, were statistically significant independent factors associated with an increase in SSI incidence (P=0.018, P=0.005, and P<0.001 respectively). Choice of skin preparation between alcoholic chlorhexidine and povidone iodine had no effect on the incidence of SSI / IWH (P=0.851 and P=0.326 respectively). The presence of SSI statistically significantly increased the post-operative length of hospital stay (from median 14 to 28 days, P=0.015)Conclusions: This is a Level 1 study which demonstrated that the use of a 5-day over a 24-hour antibiotic course can significantly reduce incidence and risk of SSI/IWH development. It has also highlighted 3 independent factors, 2 of which could be addressed during the preoperative optimisation stage to reduce the risk of developing an SSI post-operatively. The presence of SSI is associated with prolonged hospital stay, something which has significant implications on patient morbidity as well as incurring significant costs on healthcare resources.[Includes two articles published in Annals of vascular surgery (pages 254-267 of thesis, removed):https://doi.org/10.1016/j.avsg.2014.06.055 - A survey of perioperative management of major lower limb amputations : current UK practicehttps://doi.org/10.1016/j.avsg.2013.10.017 - The impact of previous surgery and revisions on outcome after major lower limb amputation

Biomechanical Evaluation of Total Ankle Replacements

Globally, 1% of the population is affected by arthritis of the foot and ankle. Total ankle replacement (TAR) was developed as an alternative to fusion to treat end-stage arthritis, however failure rates are relatively high and are often related to bony damage. The purpose of this PhD was to develop a finite element (FE) model of a TAR to examine the risk of bone failure, and how this is affected by component alignment. An experimental model of a TAR implanted into synthetic bone was first created as a means to validate an initial FE model under known conditions. Location and size of the plastic deformation were compared and good agreement was found. A FE model of the natural ankle was then created from cryosectional images obtained from the Visible Human Project®. It was analysed in the natural state and after virtual implantation with a TAR. Both the cortical stiffness and the surgical positioning of the TAR were varied to represent relevant ranges seen clinically. In the TAR models, the location of the highest stress was shifted from the region of high strength to a region of lower strength of bone. The maximum von Mises stress on the cancellous bone was primarily affected by the stiffness of cortical structure and the distance between the stem and the outer surface of the cancellous bone. In some misalignment cases, the yield stress for cancellous bone was likely to be exceeded under loads representing standing. The results indicated that the quality of the bone and the thickness of the trabecular bone surrounding the TAR stem are important factors in governing the risk of bony failure following TAR, and should be taken into account clinically. The methods developed in this thesis can now be extended to examine other TAR designs and surgical approaches