Osseointegration reduces aseptic loosening of primary distal femoral implants in pediatric and adolescent osteosarcoma patients: a retrospective clinical and radiographic study.

AIM: The challenge of distal femoral replacement (DFR) longevity remains a priority for orthopaedic oncologists as the overall survival and activity level of young patients with osteosarcoma continues to improve. This study hypothesized that increased extracortical osseointegration at the bone-implant shoulder (i.e., where the metal implant shaft abuts the femur) will improve stress transfer adjacent to the implant, as evidenced by reduced cortical bone loss, radiolucent line progression and implant failure in young patients (< 20 years) following DFR surgery. METHODS: Twenty-nine patients of mean age 13.09 ± 0.56 years received a primary DFR. The clinical outcome of 11 CPS®, 10 GMRS®, 5 Stanmore® and 3 Repiphysis® implants was evaluated over a mean follow-up period of 4.25 ± 0.55 years. The osseous response to a bone-implant shoulder composed of either a hydroxyapatite-coated grooved ingrowth collar (Stanmore®), a porous metal coating (GMRS®) or a polished metal surface (Repiphysis®) was quantified radiographically. RESULTS: All (100.0%) of the Stanmore® implants, 90.0% of GMRS®, 81.8% of CPS® and 33.3% of the Repiphysis® implants survived. Significantly increased extracortical bone and osseointegration were measured adjacent to the Stanmore® bone-implant shoulder when compared with the GMRS® and Repiphysis® implants (p < 0.0001 in both cases). Significantly decreased cortical loss was identified in the Stanmore® group (p = 0.005, GMRS® and p < 0.0001, Repiphysis®) and at 3 years, the progression of radiolucent lines adjacent to the intramedullarly stem was reduced when compared with the GMRS® and Repiphysis® implants (p = 0.012 and 0.026, respectively). CONCLUSIONS: Implants designed to augment osseointegration at the bone-implant shoulder may be critical in reducing short- (≤ 2 years) to mid- (≤ 5 years) term aseptic loosening in this vulnerable DFR patient group. Further longer-term studies are required to confirm these preliminary findings.

Incidence of Osteolysis and Aseptic Loosening Following Metal-on-Highly Cross-Linked Polyethylene Hip Arthroplasty: A Systematic Review of Studies with Up to 15-Year Follow-up.

BACKGROUND: This study compared the incidence of osteolysis, aseptic loosening, and revision following use of highly cross-linked polyethylene (HXLPE) or conventional polyethylene (CPE) at medium to long-term (>5 to 15 years) follow-up in primary total hip arthroplasty (THA). Incidences were quantified and compared with regard to age and method of implant fixation. METHODS: Using the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines, 12 randomized controlled trials and 18 cohort studies were investigated for evidence-based outcomes following HXPLE and CPE use in 2,539 hips over a 5 to 15-year follow-up. RESULTS: Lower rates of osteolysis, aseptic loosening, and implant revision were reported following use of HXLPE liners. Osteolysis was reduced from 25.4% with CPE to 4.05% with HXLPE in young patients, and from 29.7% to 6.6% in the older patient cohort. Similarities in osteolysis rates were observed when cemented (24.9% for CPE and 6.5% for HXLPE) and uncemented components (32.8% for CPE and 7.1% for HXLPE) were compared. No clear advantage in the type of HXLPE used was observed. CONCLUSIONS: Over a follow-up period of up to 15 years, when compared with CPE, use of HXLPE liners reduced the incidence of osteolysis, aseptic loosening, and implant revision, regardless of the fixation method and including in younger and potentially more active patients. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Multidrug chemotherapy causes early radiological signs of loosening in distal femoral replacements.

AIMS: Limb salvage in bone tumour patients replaces the bone with massive segmental prostheses where achieving bone integration at the shoulder of the implant through extracortical bone growth has been shown to prevent loosening. This study investigates the effect of multidrug chemotherapy on extracortical bone growth and early radiological signs of aseptic loosening in patients with massive distal femoral prostheses. METHODS: A retrospective radiological analysis was performed on adult patients with distal femoral arthroplasties. In all, 16 patients were included in the chemotherapy group with 18 patients in the non-chemotherapy control group. Annual radiographs were analyzed for three years postoperatively. Dimensions of the bony pedicle, osseointegration of the hydroxyapatite (HA) collar surface, bone resorption at the implant shoulder, and radiolucent line (RLL) formation around the cemented component were analyzed. RESULTS: A greater RLL score (p = 0.041) was observed at three years postoperatively, with those receiving chemotherapy showing greater radiological loosening compared with those not receiving chemotherapy. Chemotherapy patients experience osteolysis at the shoulder of the ingrowth collar over time (p < 0.001) compared with non-chemotherapy patients where osteolysis was not observed. A greater median percentage integration of the collar surface was observed in the non-chemotherapy group (8.6%, interquartile range (IQR) 0.0% to 37.9%; p = 0.021) at three years. Bone growth around the collar was observed in both groups, and no statistical difference in amount of extracortical bony bridging was seen. CONCLUSION: Multidrug chemotherapy affects the osseointegration of ingrowth collars and accelerates signs of radiological loosening. This may increase the risk of aseptic loosening in patients with massive segmental implants used to treat bone cancer.Cite this article: Bone Joint Res 2020;9(7):333-340.

Serum Procalcitonin as an adjunct in diagnosing prosthetic joint infection in total knee replacement and total hip replacement.

There are still many unknowns regarding the potential application of Procalcitonin (PCT) as an adjunct to aid the diagnosis of Prosthetic Joint Infection. A systematic review searching scientific articles was performed with keywords "Procalcitonin", "Total Hip Replacement", and "Total Knee Replacement" (n=123). After review of the abstract and full text for relevance, ten articles were included (n=10). Serum PCT levels for chronic Total Hip Replacement (THR) and Total Knee Replacement (TKR) have a range of mean values from 1.5 ng/ml to 14.2 ng/ml. Specificity ranges from 0.27 to 0.98, while sensitivity is from 0.33 to 0.9. On primary THR/TKR with confirmation of non-infected status, serum PCT peaks between 1-3 days post-operatively, with peak levels varying from 0.12 - 0.79 ng/ml. Based on this review, serum PCT is not a good adjunct in diagnosing Prosthetic Joint Infection (PJI). Synovial fluid PCT fluid may add better clinical support but requires further studies. There were several limitations with this review: the studies are small and heterogeneous, there was a variable definition of PJI, and there was a wide range of mean values, sensitivity and specificity.

Treatment of focal chondral lesions in the knee using a synthetic scaffold plug: Long-term clinical and radiological results.

The management of symptomatic articular cartilage lesions, especially in the young, fit individual remains an area of considerable controversy. Articular cartilage repair or reconstruction techniques may offer these patients alternatives to arthroplasty. The TruFit™ plug is a synthetic biphasic polymer scaffold that is designed for implantation at the site of a focal chondral defect. The aim of this study is to report the long-term clinical and radiological outcomes of patients treated with the TruFit™ plug for chondral defects within the knee. 11 patients underwent TruFit™ plug implantation. Long-term outcome scores were available for 6 patients at a mean follow up of 121 months (SD 12.0 months, 1 patient unavailable and 4 excluded after arthroplasty surgery). There was no statistically significant improvements in any score although all scores did improve. At a mean radiographic follow up of 70 months (17-113) of 9 patients, the mean MOCART score was 22.2 (SD 15.6). All patients had incomplete or no evidence of plug incorporation and persistent chondral loss. Based on these results, we do not recommend the use of the TruFit™ plug.

The effect of strontium and silicon substituted hydroxyapatite electrochemical coatings on bone ingrowth and osseointegration of selective laser sintered porous metal implants.

Additive manufactured, porous bone implants have the potential to improve osseointegration and reduce failure rates of orthopaedic devices. Substantially porous implants are increasingly used in a number of orthopaedic applications. HA plasma spraying-a line of sight process-cannot coat the inner surfaces of substantially porous structures, whereas electrochemical deposition of calcium phosphate can fully coat the inner surfaces of porous implants for improved bioactivity, but the osseous response of different types of hydroxyapatite (HA) coatings with ionic substitutions has not been evaluated for implants in the same in vivo model. In this study, laser sintered Ti6Al4V implants with pore sizes of Ø 700 µm and Ø 1500 µm were electrochemically coated with HA, silicon-substituted HA (SiHA), and strontium-substituted HA (SrHA), and implanted in ovine femoral condylar defects. Implants were retrieved after 6 weeks and histological and histomorphometric evaluation were compared to electrochemically coated implants with uncoated and HA plasma sprayed controls. The HA, SiHA and SrHA coatings had Ca:P, Ca:(P+Si) and (Ca+Sr):P ratios of 1.53, 1.14 and 1.32 respectively. Electrochemically coated implants significantly promoted bone attachment to the implant surfaces of the inner pores and displayed improved osseointegration compared to uncoated scaffolds for both pore sizes (p<0.001), whereas bone ingrowth was restricted to the surface for HA plasma coated or uncoated implants. Electrochemically coated HA implants achieved the highest osseointegration, followed by SrHA coated implants, and both coatings exhibited significantly more bone growth than plasma sprayed groups (p≤0.01 for all 4 cases). SiHA had significantly more osseointegration when compared against the uncoated control, but no significant difference compared with other coatings. There was no significant difference in ingrowth or osseointegration between pore sizes, and the bone-implant-contact was significantly higher in the electrochemical HA than in SiHA or SrHA. These results suggest that osseointegration is insensitive to pore size, whereas surface modification through the presence of an osteoconductive coating plays an important role in improving osseointegration, which may be critically important for extensively porous implants.

Partial Bone Formation in Additive Manufactured Porous Implants Reduces Predicted Stress and Danger of Fatigue Failure.

New porous implant designs made possible by additive manufacturing allow for increased osseointegration, potentially improving implant performance and longevity for patients that require massive bone implants. The aim of this study was to evaluate how implantation and the strain distribution in the implant affect the pattern of bone ingrowth and how changes in tissue density within the pores alter the stresses in implants. The hypothesis was that porous metal implants are susceptible to fatigue failure, and that this reduces as osteointegration occurs. A phenomenological, finite element analysis (FEA) bone remodelling model was used to predict partial bone formation for two porous (pore sizes of 700 µm and 1500 µm), laser sintered Ti6Al4V implants in an ovine condylar defect model, and was compared and verified against in vivo, histology results. The FEA models predicted partial bone formation within the porous implants, but over-estimated the amount of bone-surface area compared to histology results. The stress and strain in the implant and adjacent tissues were assessed before, during bone remodelling, and at equilibrium. Results showed that partial bone formation improves the stress distribution locally by reducing stress concentrations for both pore sizes, by at least 20%. This improves the long-term fatigue resistance for the larger pore implant, as excessively high stress is reduced to safer levels (86% of fatigue strength) as bone forms. The stress distribution only changed slightly in regions without bone growth. As the extent of bone formation into extensively porous bone implants depends on the level of stress shielding, the design of the implant and stiffness have significant influence on bone integration and need to be considered carefully to ensure the safety of implants with substantial porous regions. To our knowledge this is the first time that the effect of bone formation on stress distribution within a porous implant has been described and characterised.

The Outcome of Revision Surgery for Failed Metal-on-Metal Total Hip Arthroplasty.

BACKGROUND: Metal-on-metal total hip arthroplasties (MoM THAs) are frequently revised, though there is a paucity of functional outcome data. We report on outcomes and prognostic factors predictive of outcome from the largest series of MoM THA revisions to date. METHODS: A single-center consecutive series of revisions from MoM THAs was identified. The cohort was divided by the presence or absence of symptoms prior to revision. The primary outcome was functional outcome (Oxford Hip Score [OHS]). Secondary outcomes were complication data, pre-revision and post-revision blood metal ions, and modified Oxford classification of pre-revision magnetic resonance imaging. RESULTS: One hundred eighty revisions at median follow-up of 5.48 years were identified. Median OHS improved from 29 to 37 with revision (P < .001). Symptomatic patients experienced the greatest functional benefit (ΔOHS 6.5 vs 1.4, P = .012), while the function of asymptomatic patients was unaffected by revision (P = .4). Use of a cobalt-chromium-containing bearing surface at revision and increased body mass index were predictive of poor functional outcome. CONCLUSION: Symptomatic patients experience greater functional benefit from revision surgery but do not regain the same level of function as patients who were asymptomatic prior to revision. Body mass index and use of cobalt-chromium-containing bearing surfaces are prognostic for poor functional outcome.

Mid-bundle positioning of the femoral socket increases graft rupture in anatomic single bundle anterior cruciate ligament reconstruction.

BACKGROUND: Anatomic anterior cruciate ligament (ACL) reconstructions are superior to non-anatomic graft placements with regard to controlling rotational laxity. Different techniques of anatomic single-bundle reconstruction exist. The femoral tunnel may be placed in a mid-bundle position (MB) or within the anteromedial bundle footprint (AM) with no definitive consensus as to the preferred position. Our institution, reflecting trends in surgical practice, has experience with both techniques. METHODS: Interrogation of our prospectively maintained database yielded all primary ACL reconstructions performed using the anatomic TransLateral single-bundle all-inside technique. A two year minimum follow-up was set. The failure rate of the MB and AM cohorts was compared as a primary outcome. Patient-reported outcomes across cohorts at several time-points were analysed as a secondary outcome. RESULTS: Two hundred and seventy-nine primary ACL reconstructions were identified at a median follow-up of 49 months. MB positioning was utilised in 113 cases (40.5%) and AM positioning in 166 (59.5%). There were significantly more failures in the MB cohort (p = 0.029). Logistic regression revealed mid-bundle femoral positioning was associated with greater than fourfold increase in graft failure (odds ratio 4.14, p = 0.039). CONCLUSION: Data from this case series suggests that amongst anatomic single-bundle ACL reconstructions, grafts with a mid-bundle femoral tunnel are more than four times more likely to fail versus those with a femoral tunnel placed four millimetres deeper within the anteromedial bundle footprint.

Novel adaptive finite element algorithms to predict bone ingrowth in additive manufactured porous implants.

Bone loss caused by stress shielding of metallic implants is a concern, as it can potentially lead to long-term implant failure. Surface coating and reducing structural stiffness of implants are two ways to improve bone ingrowth and osteointegration. Additive manufacturing, through selective laser sintering (SLS) or electron beam melting (EBM) of metallic alloys, can produce porous implants with bone ingrowth regions that enhance osteointegration and improve clinical outcomes. Histology of porous Ti6Al4V plugs of two pore sizes with and without electrochemically deposited hydroxyapatite coating, implanted in ovine condyles, showed that bone formation did not penetrate deep into the porous structure, whilst significantly increased bone growth along coated pore surfaces (osteointegration) was observed. Finite Element simulations, combining new algorithms to model bone ingrowth and the effect of surface modification on osteoconduction, were verified with the histology results. The results showed stress shielding of porous implants made from conventional titanium alloy due to material stiffness and implant geometry, limiting ingrowth and osteointegration. Simulations for reduced implant material stiffness predicted increased bone ingrowth. For low modulus Titanium-tantalum alloy (Ti-70%Ta), reduced stress shielding and enhanced bone ingrowth into the porous implant was found, leading to improved mechanical interlock. Algorithms predicted osteoconductive coating to promote both osteointegration and bone ingrowth into the inner pores when they were coated. These new Finite Element algorithms show that using implant materials with lower elastic modulus, osteoconductive coatings or improved implant design could lead to increased bone remodelling that optimises tissue regeneration, fulfilling the potential of enhanced porosity and complex implant designs made possible by additive layer manufacturing techniques.

Imaging of foreign bodies: a radiological conundrum.

A 24-year-old woman escaped a fire by jumping from the first floor of her house onto a temporary greenhouse. She was brought into the emergency department and later treated surgically. Three years after the initial episode a tender lump in her right thigh was found during regular follow-up for her acute myeloid leukaemia, for which she was in remission. This was treated as a suspicious mass due to her haematological history and further imaging was organised. This was later identified as a piece of the greenhouse that she had landed on 7 years previously. It is a common occurrence for foreign bodies to be missed on initial examination. Fortunately the patient recovered well from her physical wounds and, more importantly, remains humorous when reflecting on her almost 7-year long battle with a piece of plastic.

Enhancing Postoperative Rehabilitation Following Knee Arthroplasty Using a New Cryotherapy Product: A Prospective Study.

To compare a novel cooling product, Physicool (P, Physicool Ltd, London, England, UK) with a well-established cryotherapy system, Cryocuff (C, Aircast, DJO Global, Vista, California, USA) using pain scores, range of movement (ROM), and cost as outcome measures in the early phase following total knee arthroplasty. We prospectively studied 90 consecutive patients undergoing unilateral total knee arthroplasty by a single surgeon. Following exclusions, 40 patients were recruited to each group. Visual analogue scale (VAS) for pain and ROM before and after application of cooling device was recorded at 24 and 48 hours after surgery. The cost of treatment per patient was also calculated. The VAS were significantly reduced in P on day 1 postsurgery (p = 0.013) and day 2 (p = 0.001) compared to C. A significant increase in ROM was recorded in P at 24 hours (p = 0.004) and at 48 hours (p = 0.009) postsurgery compared to C. The cost benefit of using P over C was approximately £25 per patient. The Physicool system is a safe and effective cooling method for improving pain and ROM in the early postoperative phase following total knee arthroplasty. Furthermore, it offers substantial cost savings.

The service impact of failed locking plate fixation of distal tibial fractures: a service and financial evaluation at a major trauma centre.

INTRODUCTION: The surgical treatment of distal tibial fractures is challenging and controversial. Recently, locking plate fixation has become popular, but the outcomes of this treatment are mixed with complication rates as high as 50 % in the published literature. There are no reports specifically relating to the financial and resource costs of failed treatment in the literature. METHOD: Retrospective service analysis of patients who had undergone locking plate fixation of a distal third tibial fracture between 2008 and 2011 with at least 12 months follow-up. Rates of readmission, reoperation, bony union and infection were ascertained. The financial and resource (hospital stay and number of outpatient appointments) implications of failed treatment were calculated. RESULTS: Forty-two patients were identified. There were 31 type A fractures, one type B fracture and 10 type C fractures. Three injuries were open. Twenty patients were treated with minimally invasive percutaneous osteosynthesis (MIPO). The readmission and reoperation rates were 26 % (n = 11) and 19 % (n = 8), respectively. A total of 89 % of readmissions were due to infection. All patients had received appropriate antibiotic regimens. The average costs of successful and failed treatment were £ 5538 and £ 18,335, respectively. The average time to union was 24.5 weeks. The rate of non-union was 21 % (n = 9). The rate of infection was 28 % (n = 12), with all patients with open fracture incurring an infection. Tourniquet time had no effect on the incidence of complications. Smokers were more likely to incur a complication (p < 0.05), and non-union was lower in the MIPO group (p < 0.05). The length and total cost of inpatient care were significantly lower in the MIPO group (p < 0.05). MIPO patients were five times less likely to incur readmission or reoperation. Failed treatment was three times more expensive and four times longer than successful treatment. CONCLUSION: The study identified a large burden to the service following failure of locking plate treatment of these fractures, but the outcomes were similar to series published in the literature. Readmission rates were high following these injuries, and failed treatment was costly and had a significant impact on hospital resources. The implementation of major trauma networks and centralised subspecialised units should improve quality and value for money.

Systematic review: the safety of intra-articular corticosteroid injection prior to total knee arthroplasty.

BACKGROUND: Up to 30% of patients undergoing total knee arthroplasty (TKA) have received intra-articular corticosteroid injections prior to surgery. Debate exists as to whether such injections increase the rate of post-operative infection. Given that deep infection is a disastrous complication, a systematic review of the literature was undertaken to evaluate the safety of intra-articular corticosteroid injections given prior to TKA. Other features of corticosteroid use are also discussed including mechanism of action and optimal dosage. METHODS: Using PRISMA guidelines, EMBASE, CINAHL and MEDLINE databases were searched using the search terms 'total knee arthroplasty', 'replacement', 'corticosteroid', 'steroid', 'infection', 'safety', and relevant articles critically appraised. The Newcastle-Ottawa Scale was used to assess for bias. RESULTS: No level one or two studies were available for review. Two retrospective case control studies and two cohort studies (level three evidence) which specifically evaluated the risk of infected TKA in association with pre-operative steroid injection were reviewed: three showed that prior steroid injection was not associated with increased infection rates; one article showed that prior steroid injection was associated with a significantly increased risk of deep infection post-TKA. CONCLUSION: Clinicians commonly administer steroid injections to patients who are candidates for TKA but may be unaware of the potential long term complications. The included studies were underpowered and at risk of selection bias and only one study demonstrated an increased risk of infection post-operatively. We recommend that further research is required to evaluate the safety of steroid injection prior to TKA. LEVEL OF EVIDENCE: III.

Postoperative vision loss after reverse shoulder arthroplasty.

We report a case which highlights the rare but devastating complication of postoperative vision loss (POVL) in orthopaedic surgery. Though documented previously, it has not been reported in shoulder arthroplasty surgery of which we present the first case. The aetiology of POVL is difficult to elucidate due to its elusive nature. We explain the risks associated with regional blocks used for such surgery and how this may be related to POVL. We must be vigilant of the possible causes of POVL as curative treatment is often not possible and hence must take preventative measures which we have recommended. Fortunately, the patient fully recovered at 10 months postoperatively with excellent function of her reverse shoulder arthroplasty.

Ignition of free gas in the peritoneal cavity: an explosive complication.

We report an extremely rare event where the use of diathermy to enter the peritoneal cavity caused the free gas within it to ignite and consequently burn the surgeon during a standard right hemicolectomy procedure for a caecal perforation. This should be noted as a possible safety concern intraoperatively. We conclude that sharp dissection should always be used initially when entering the peritoneal cavity where free gas is present, cautery can subsequently be used once the free air has escaped.