Thermal injury to the radial nerve caused by cement leakage is a rare complication after revision elbow arthroplasty. Several reports have described nerve palsy caused by cement leakage after hip arthroplasty. However, little information is available regarding whether radial nerve injury due to cement leakage after humeral stem revision will recover. In a recent study, radial nerve palsy occurred in 2 of 7 patients who had thermal injury from leaked cement during humeral component revisions. These patients did not regain function of the radial nerve after observation. We present a case of functional recovery from a radial nerve palsy caused by cement leakage after immediate nerve decompression in revision elbow arthroplasty[Fig. 1.2]

Objectives. Prosthetic joint infection (PJI) is a devastating complication following total joint arthroplasty. Non-contact induction heating of metal implants is a new and emerging treatment for PJI. However, there may be concerns for potential tissue necrosis. It is thought that segmental induction heating can be used to control the thermal dose and to limit collateral thermal injury to the bone and surrounding tissues. The purpose of this study was to determine the thermal dose, for commonly used metal implants in orthopaedic surgery, at various distances from the heating centre (HC). Methods. Commonly used metal orthopaedic implants (hip stem, intramedullary nail, and locking compression plate (LCP)) were heated segmentally using an induction heater. The thermal dose was expressed in cumulative equivalent minutes at 43°C (CEM43) and measured with a thermal camera at several different distances from the HC. A value of 16 CEM43 was used as the threshold for thermal damage in bone. Results. Despite high thermal doses at the HC (7161 CEM43 to 66 640 CEM43), the thermal dose at various distances from the HC was lower than 16 CEM43 for the hip stem and nail. For the fracture plate without corresponding metal screws, doses higher than 16 CEM43 were measured up to 5 mm from the HC. Conclusion. Segmental induction heating concentrates the thermal dose at the targeted metal implant areas and minimizes collateral thermal injury by using the non-heated metal as a heat sink. Implant type and geometry are important factors to consider, as they influence dissipation of heat and associated collateral thermal injury. Cite this article: B. G. Pijls, I. M. J. G. Sanders, E. J. Kuijper, R. G. H. H. Nelissen. Segmental induction heating of orthopaedic metal implants. Bone Joint Res 2018;7:609–619. DOI: 10.1302/2046-3758.711.BJR-2018-0080.R1

According to the latest report from the German Arthroplasty Registry, aseptic loosening is the primary cause of implant failure following primary hip arthroplasty. Osteolysis of the proximal femur due to the stress-shielding of the bone by the implant causes loss of fixation of the proximal femoral stem, while the distal stem remains fixed. Removing a fixed stem is a challenging process. Current removal methods rely on manual tools such as chisels, burrs, osteotomes, drills and mills, which pose the risk of bone fracture and cortical perforation. Others such as ultrasound and laser, generate temperatures that could cause thermal injury to the surrounding tissues and bone. It is crucial to develop techniques that preserve the host bone, as its quality after implant removal affects the outcome of a revision surgery. A gentler removal method based on the transcutaneous heating of the implant by induction is proposed. By reaching the glass transition temperature (T. G. ) of the periprosthetic cement, the cement is expected to soften, enabling the implant to be gently pulled out. The in-vivo environment comprises body fluids and elevated temperatures, which deteriorate the inherent mechanical properties of bone cement, including its T. G. We aimed to investigate the effect of fluid absorption on the T. G. (ASTM E2716-09) and Vicat softening temperature (VST) (ISO 306) of Palacos R cement (Heraeus Medical GmbH) when dry and after storage in Ringer's solution for up to 8 weeks. Samples stored in Ringer's solution exhibited lower T. G. and VST than those stored in air. After 8 weeks, the T. G. decreased from 95.2°C to 81.5°C in the Ringer's group, while the VST decreased from 104.4°C to 91.9°C. These findings will be useful in the ultimate goal of this project which is to design an induction-based system for implant removal. Acknowledgements: Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – SFB/TRR-298-SIIRI – Project-ID 426335750

Purpose:. Tuberosity healing in hemiarthroplasty for proximal humerus fractures remains problematic. Improved implant design and better techniques for tuberosity fixation have not been met with improved clinical results. The etiology for tuberosity failure is multifactorial; however thermal injury to host bone is a known effect of using polymethylmethacrylate for implant fixation. We hypothesized that the effect of thermal injury at the tuberosity shaft junction could be diminished by utilizing an impaction grafting technique for hemiarthroplasty stems. Methods:. Five matched pairs of cadaveric humeri were skeletonized and hemiarthroplasty stems were implanted in the proximal humeri in two groups. The first group had full cementation utilized from the surgical neck to 2 cm distal to the stem (cement group) and the second group had distal cementation with autologous cancellous bone graft impacted in the proximal 2.5 cm of the stem (impaction grafting group). Thermocouples were used to measure the inner cortical temperature at the tip of the stem, surgical neck, and at the level of the cement-graft interface for both treatment groups (see Fig. 1). Experiments were initiated with the humeri fully submerged in 0.9% sodium chloride and all three thermocouples registering a temperature of 37 ± 1°C. Statistical analyses were performed with a one-sided, paired t-test. Results:. The maximum recorded cortical bone temperature at the surgical neck was significantly decreased by 23% from 52.4 ± 8.1°C in the cement group to 40.4 ± 4.8°C in the impaction grafting group (p = 0.037). We identified no significant differences in maximum recorded temperature at the cement-graft interface between the impaction grafting group (44.3 ± 6.3°C) and the cement group (47.4 ± 6.4°C) (p = 0.254). A similar finding was observed between groups at the tip of the hemiarthroplasty stem (impaction grafting group 54.2 ± 5.7°C; cemented group 52.3 ± 7.3°C, p = 0.303). Conclusion:. Given the known threshold of 47°C as the onset of permanent thermal injury to bone,. 1. impaction grafting maintains the temperature at the surgical neck during cementation below this critical value. Impaction grafting may serve as a beneficial surgical technique to mitigate the effects of thermal injury on tuberosity healing in proximal humeral hemiarthroplasty for fracture

Introduction: The curing of polymethylmethacrylate cement is an exothermic reaction, with temperatures reaching 80oC. Thus contact with cement can result in thermal injury. During orthopaedic procedures bone cement may be inadvertently left lying on surgical drapes. This study aims to investigate the effect of drapes on the contact temperature of such cement. Methods: The experiment was carried out in an orthopaedic theatre with a constant temperature and humidity. Polymethylmethacrylate cement was prepared and pieces of cement of a specific size were investigated. Experiment one measured the contact temperature of curing cement in isolation. Experiment two and three investigated the effect of one and two layers of surgical drape respectively on contact temperature. Results: The mean maximum temperature reached in experiments one, two and three was 75oC, 71oC and 69oC respectively. The maximum temperature was reached quickest in experiment three. In considering the time period that the contact temperature remained above 40oC this was longest in experiment three at 750s followed by experiment 2 and then experiment 1 at 525s and 330s respectively. Contact temperature graphs for each experiment have been plotted in figure.1. Discussion: One might think that drapes provide a protective barrier between a patient’s skin and bone cement, however this is incorrect. The drapes insulate the exothermic reaction of curing bone cement which tends to accelerate the reaction. Furthermore the insulating effect of drapes causes curing bone cement to lose heat at a slower rate resulting in the contact temperature remaining above 40oC for longer; this increases the potential for thermal injury. This study demonstrates that a specific effort should be made to ensure bone cement is not inadvertently left lying on surgical drapes

Bone cement reaches high temperatures while polymerising. Bone has been shown to be sensitive to thermal injury with osteonecrosis reported after one minute at 47°C. Necrosis during cementing might compromise the bone-cement interface. Some surgeons fill the joint cavity with irrigation fluid to provide a heatsink during cementing, but this has not been supported by research. We used a model acetabulum in a bovine humerus to allow measurement of bone temperatures in cementing. Models were prepared with a 50mm diameter acetabulum and three temperature probe holes. Four warmed models were cemented with Palacos RG using a standard mixing system and a 10mm UMHWPE disc to represent an acetabular component. Two of the acetabular models were filled with room temperature water to provide a heatsink. An electronic probe measured temperature at 5 second intervals from the moment of cementing. In the models with no heatsink, peak temperature was 40.3°C. The highest temperature rise was 7.5°C. In the models with a heatsink, there was a mean fall of 4.4°C. These results suggest that using a heatsink while cementing prostheses may reduce the peak bone temperature

The well-fixed cemented femoral stem and surrounding cement can be challenging to remove. Success requires evaluation of the quality of the cement mantle (interface lucency), position of the stem, extent of cement below the tip of the stem and skill with the specialised instruments and techniques needed to remove the stem and cement without perforating the femur. Smooth surfaced stems can usually be easily removed from the surrounding cement mantle with a variety of stem extractors that attach to the trunnion or an extraction hole on the implant. Roughened stems can be freed from the surrounding cement mantle with osteotomes or a narrow high speed burr and then extracted with the above instruments. Following this, the well-fixed cement mantle needs to be removed. Adequate exposure and visualization of the cement column is essential to remove the well-fixed cement without damage to the bone in the femur. This is important since fixation of a revision femoral component typically requires at least 4 cm of contact with supportive cortical bone, which can be difficult to obtain if the femur is perforated or if the isthmus damaged. Proximally, cement in the metaphyseal region can be thinned with a high speed burr, then split radially and removed piecemeal. It is essential to remember that both osteotomes and high speed burrs will cut thru bone easier than cement and use of these instruments poses a substantial risk of unintended bone removal and perforation of the femur if done improperly. These instruments should, as a result, be used under direct vision. Removal of more distal cement in the femur typically requires use of an extended femoral osteotomy (ETO) to allow for adequate access to the well-fixed cement in the bowed femoral canal. An ETO also facilitates more efficient removal of cement in the proximal femur. The ETO should be carefully planned so that it is distal enough to allow for access to the end of the cement column and still allow for stable fixation of a new implant. Too short of an ETO increases the risk of femoral perforation since the straight cement removal instruments cannot negotiate the bowed femoral canal to access the end of the cement column without risk of perforation. An ETO that is too distal makes cement removal easier, but may not allow for sufficient fixation of a new revision femoral stem. Cement below the level of the ETO cannot be directly visualised and specialised instruments are necessary to safely remove this distal cement. Radiofrequency cement removal devices use high frequency (ultrasonic) radio waves to melt the cement within the canal. Although cement removal with these devices is time consuming and tedious, they do substantially reduce the chances of femoral perforation. These devices can, however, generate considerable heat locally and can result in thermal injury to the bone and surrounding tissues. Once the distal end of the cement mantle is penetrated, backbiting or hooked curettes can be use to remove any remaining cement from within the canal. It is important that all cement be removed from the femur since reamers used for preparation of the distal canal will be deflected by any retained cement, which could result in eccentric reaming and inadvertent perforation of the femur and make fixation of a new implant very challenging. An intra-operative x-ray can be very helpful to insure that all cement has been removed before reaming is initiated. One should always plan for a possible femoral perforation and have cortical strut grafts and a stem available that will safely bypass the end of the cement column and the previous cement restrictor

Aims

The risk of postoperative complications after resection of soft-tissue sarcoma in the medial thigh is higher than in other locations. This study investigated whether a vessel sealing system (VSS) could help reduce the risk of postoperative complications after wide resection of soft-tissue sarcoma in the medial thigh.

Aims

Electromagnetic induction heating has demonstrated in vitro antibacterial efficacy over biofilms on metallic biomaterials, although no in vivo studies have been published. Assessment of side effects, including thermal necrosis of adjacent tissue, would determine transferability into clinical practice. Our goal was to assess bone necrosis and antibacterial efficacy of induction heating on biofilm-infected implants in an in vivo setting.

The well-fixed cemented femoral stem and surrounding cement can be challenging to remove. Success requires evaluation of the quality of the cement mantle (interface lucency), position of the stem, extent of cement below the tip of the stem and skill with the specialised instruments and techniques needed to remove the stem and cement without perforating the femur. Smooth surfaced stems can usually be easily removed from the surrounding cement mantle with a variety of stem extractors that attach to the trunnion or an extraction hole on the implant. Roughened stems can be freed from the surrounding cement mantle with osteotomes or a narrow high speed burr and then extracted with the above instruments. Following this, the well fixed cement mantle needs to be removed. Adequate exposure and visualization of the cement column is essential to remove the well-fixed cement without damage to the bone in the femur. This is important since fixation of a revision femoral component typically requires at least 4cm of contact with supportive cortical bone, which can be difficult to obtain if the femur is perforated or if the isthmus damaged. Proximally, cement in the metaphyseal region can be thinned with a high speed burr, then split radially and removed piecemeal. It is essential to remember that both osteotomes and high speed burrs will cut thru bone easier than cement and use of these instruments poses a substantial risk of unintended bone removal and perforation of the femur if done improperly. These instruments should, as a result, be used under direct vision. Removal of more distal cement in the femur typically requires use of an extended femoral osteotomy (ETO) to allow for adequate access to the well-fixed cement in the bowed femoral canal. An ETO also facilitates more efficient removal of cement in the proximal femur. The ETO should be carefully planned so that it is distal enough to allow for access to the end of the cement column and still allow for stable fixation of a new implant. Too short of an ETO increases the risk of femoral perforation since the straight cement removal instruments cannot negotiate the bowed femoral canal to access the end of the cement column without risk of perforation. An ETO that is too distal makes cement removal easier, but may not allow for sufficient fixation of a new revision femoral stem. Cement below the level of the ETO cannot be directly visualised and specialised instruments are necessary to safely remove this distal cement. Radiofrequency cement removal devices (OSCAR) use high frequency (ultrasonic) radio waves to melt the cement within the canal. Although cement removal with these devices is time consuming and tedious, they do substantially reduce the chances of femoral perforation. These devices can, however, generate considerable heat locally and can result in thermal injury to the bone and surrounding tissues. Once the distal end of the cement mantle is penetrated, backbiting or hooked curettes can be used to remove any remaining cement from within the canal. It is important that all cement be removed from the femur since reamers used for preparation of the distal canal will be deflected by any retained cement, which could result in eccentric reaming and inadvertent perforation of the femur and make fixation of a new implant very challenging. An intraoperative x-ray can be very helpful to insure that all cement has been removed before reaming is initiated

The causes of a stiff elbow are numerous including: post-traumatic elbow, burns, head injury, osteoarthritis, inflammatory joint disease and congenital. Types of stiffness include: loss of elbow flexion, loss of elbow extension and loss of forearm rotation. All three have different prognoses in terms of the timing of surgery and the likelihood of restoration of function. Contractures can be classified into extrinsic and intrinsic (all intrinsic develop some extrinsic component). Functional impairment can be assessed medicolegally; however, in clinical practice the patient puts an individual value on the arc of motion. Objectively most functions can be undertaken with an arc of 30 to 130 degrees. The commonest cause of a Post-traumatic Stiff elbow is a radial head fracture or a complex fracture dislocation. Risk factors for stiffness include length of immobilisation, associated fracture with dislocation, intra-articular derangement, delayed surgical treatment, associated head injury, heterotopic ossification. Early restoration of bony columns and joint stability to allow early mobilisation reduces incidence of joint stiffness. Heterotopic ossification (HO) is common in fracture dislocation of the elbow. Neural Axis trauma alone causes HO in elbows in 5%. However, combined neural trauma and elbow trauma the incidence is 89%. Stiffness due to thermal injury is usually related to the degree rather than the site. The majority of patients have greater than 20% total body area involved. Extrinsic contractures are usually managed with a sequential release of soft tissues commencing with a capsular excision (retaining LCL/MCL), posterior bundle of the MCL +/− ulna nerve decompression (if there is loss of flexion to 100 degrees). This reliably achieved via a posterior incision, a lateral column exposure +/− ulna nerve mobilisation. A medial column exposure is a viable alternative. Arthroscopic capsular release although associated with a quicker easier rehabilitation is associated with increased neural injury. Timing of release is specific to the type of contracture, i.e. flexion contractures after approx. six months, extension contractures ASAP but after four months, loss of forearm rotation less 6 to 24 months. The use of Hinged Elbow Fixators is increasing. The indications include reconstructions that require protection whilst allowing early movement, persistent instability or recurrent/late instability or interposition arthroplasty. Post-operative rehabilitation requires good analgesia, joint stability and early movement. The role of CPM is often helpful but still being evaluated

During revision hip surgery, damage to the sciatic nerve is due most commonly to excessive tension. While the nerve is strong in tension and is able to tolerate this remarkably, it is sensitive to lateral compression against angled structures and it is likely that tension causes injury by such pressure. In a personal series of 441 revision hip procedures, sciatic nerve injury occurred in 9 recognised cases:. 2 were complete with no useful recovery. 2 were severe with some incomplete recovery. 3 were predominantly lateral popliteal with incomplete recovery. 2 were transient and clinically fully recovered. In only two of these were the cause and the time of injury identifiable. In these cases, pain was not a serious feature but in eight separate medico-legal cases, burning pain of variable distribution has been the most serious complaint. Medical negligence has been successfully sustained on the grounds of res ipsa locitur. Regrettably, patients must be given informed consent with yet another potential hazard being listed. We have found that in normal individuals the range of straight leg raising varies between 30 and 90 degrees. Towards the limit of this range the nerve is tight and a crude cadaveric test indicated a tension force of 40 newtons! In an athlete this may be extreme and yet the nerve does not complain. Excluding direct compression (e.g. by a retractor) and thermal injury, we suggest that the tension developed during unguarded straight leg raising while the patient is still anaesthetised is a serious risk factor. After even conservative lengthening, the tension rises alarmingly during such action. It is possible that pre-existing lumbar degenerative disk disease can contribute to the hazard and be source of pain

Injection of PMMA bone cement into fractured vertebral bodies has been used clinically and proved to be effective. However, there are concerns about thermal injury to the cord and interferece of bone remodling .The purpose of this study is to use the biodegradable bone substitute as an alternative for augumentation of fractured vertebral bodies . Material and Methods: From April 1998 to January 2000, 10 patients(Nine females and one male, age from 55 to 74 years) with osteoporotic compression fractures were retrospectively reviewed. The level of compression fracture mostly occurred at T12-L1 (Nine of ten cases). Eight of the ten cases were osteonecrosis of vertebral body with vaccum phenomenon. While other two cases had gross kyphotic deformity. Surgical indications for these ten patients include back pain, progressive kyphosis and failure of conservative medical treatment. (No neurological deficits were noted in all ten cases.) All ten cases underwent posterior instrumentation with vertebroplasty (Bipedicle impaction of osteoset and iliac bone autograft). The anterior body height and the kyphotic angle were measured preoperatively and postoperatively. The fusion mass was observed and followed up with T-L spine AP and Lateral X-ray regularly. Result: The anterior body height increased over 50% in all cases in this series. The average correction of kyphosis angle is 10 degree. Stable arthrodesis with obvious fusion mass occurred in all patients under X-ray image. Postoperative pain relief were noted in all ten patients. No major complications were related to this procedure. Conclusion: This preliminary study shows that vertebroplasty using osteoconductive biodegradable bone substitute and osteoinductive iliac bone autograft in osteoporotic compression fracture with osteonecrosis is feasable and effective. The technique might also provide an alternative for treatment of osteoporotic compression fractures instead of PMMA bone cement

Introduction: Knee arthroscopy is one of the most commonly performed orthopaedic procedures. All orthopaedic surgeons have heard anecdotal stories of thermal injury and drape combustion, yet a literature search has failed to find any papers reviewing the nature of such risks. Materials and methods: A thermocouple attached to a laptop computer was used to record the temperature at the arthroscope tip, the light cable end and the light source generator. All potentially flammable materials commonly used during arthroscopic surgery (various disposable drapes, cotton drapes, gowns, paper towels and swabs), were placed at measured distances from a) the light cable end and b) the arthroscope tip. Results: The arthroscope tip reached a maximum temperature of 41.90° in 200 seconds. The light cable tip reached 80° at 100 seconds and a maximum temperature of 110°C in 342 seconds. The light source generator reached a temperature of 153°C. All materials tested (except cotton swabs) underwent signs of combustion. The disposable drapes burnt most rapidly. None of the materials considered had any evidence of thermal damage when placed at distances of 2.5 cm beyond the light cable and 0.5 cm beyond the arthroscope tip. Combustion was most rapid at a distance of 5mm from the instruments. Most surgeons consider the arthroscope tip or light cable end to be the site most likely to induce combustion. Fuel, heat and oxygen are required to produce combustion. Direct contact with the tip results in greater exposure to heat but lower oxygen availability. The fasted combustion occurred at 5mm due to higher oxygen availability despite a lower temperature. Conclusions and Recommendations:. Disposable drapes will burn with the light cable and the arthroscope tip. The arthroscope tip and light cable end should not be left to rest against the drapes because thermal burns can occur within seconds. A kidney dish should be used to contain the instruments when not in the surgeon’s hands. The light source should be switched on only when the light cable is connected to the arthroscope. A retractable shield of 2.5mm is fitted to the light cable end

Aims

The aims of this study were to validate the outcome of total elbow arthroplasty (TEA) in patients with rheumatoid arthritis (RA), and to identify factors that affect the outcome.

Objectives

Metal-on-metal hip resurfacing (MOMHR) is available as an alternative option for younger, more active patients. There are failure modes that are unique to MOMHR, which include loosening of the femoral head and fractures of the femoral neck. Previous studies have speculated that changes in the vascularity of the femoral head may contribute to these failure modes. This study compares the survivorship between the standard posterior approach (SPA) and modified posterior approach (MPA) in MOMHR.