The incidence of anterior knee pain following total knee replacement (TKR) is reported to be as high as 49%. The source of the pain is poorly understood but the soft tissues around the patella have been implicated. In theory circumferential electrocautery denervates the patella thereby reducing efferent pain signals. However, there is mixed evidence that this practice translates into improved outcomes. We aimed to investigate the clinical effect of intra-operative circumpatellar electrocautery in patients undergoing TKR using the LCS mobile bearing or Kinemax fixed bearing TKR. A total of 200 patients were randomised to receive either circumpatellar electrocautery (diathermy) or not (control). Patients were assessed by visual analogue scale (VAS) for anterior knee pain and Oxford knee score (OKS) pre-operatively and three months, six months and one year post-operatively. Patients and assessors were blinded. There were 91 patients in the diathermy group and 94 in the control. The mean VAS improvement at one year was 3.9 in both groups (control; -10 to 6, diathermy;. -9 to 8, p < 0.001 in both cases, paired, two-tailed t-test). There was no significant difference in VAS between the groups at any other time. The mean OKS improvement was 17.7 points (0 to 34) in the intervention group and 16.6 (0 to 42) points in the control (p = 0.36). There was no significant difference between the two groups in OKS at any other time. We found no relevant effect of patellar electrocautery on either VAS anterior knee pain or OKS for patients undergoing LCS and Kinemax TKR

The efficacy of circumpatellar electrocautery in reducing the incidence of post-operative anterior knee pain is unknown. We conducted a single-centre, outcome-assessor and patient-blinded, parallel-group, randomised, controlled trial to compare circumpatellar electrocautery with no electrocautery in total knee replacement in the absence of patellar resurfacing. Patients requiring knee replacement for primary osteoarthritis were randomly assigned circumpatellar electrocautery (intervention group) or no electrocautery (control group). The primary outcome measure was the incidence of anterior knee pain. A secondary measure was the standardised clinical and patient-reported outcomes determined by the American Knee Society scores and the Western Ontario and McMaster Universities (WOMAC) osteoarthritis index. A total of 131 knees received circumpatellar electrocautery and 131 had no electrocautery. The overall incidence of anterior knee pain at follow-up at one year was 26% (20% to 31%), with 19% (12% to 26%) in the intervention group and 32% (24% to 40%) in the control group (p = 0.02). The relative risk reduction from electrocautery was 40% (9% to 61%) and the number needed to treat was 7.7 (4.3 to 41.4). The intervention group had a better mean total WOMAC score at follow-up at one year compared with the control group (16.3 (0 to 77.7) versus 21.6 (0 to 76.7), p = 0.04). The mean post-operative American Knee Society knee scores and function scores were similar in the intervention and control groups (knee score: 92.4 (55 to 100) versus 90.4 (51 to 100), respectively (p = 0.14); function score: 86.5 (15 to 100) versus 84.5 (30 to 100), respectively (p = 0.49)). Our study suggests that in the absence of patellar resurfacing electrocautery around the margin of the patella improves the outcome of total knee replacement

The management of the patella during total knee replacement is controversial. In some studies the absence of patellar resurfacing results in residual anterior knee pain in over 10% of patients. One form of treatment which may be used in an endeavour to reduce this is circumferential patellar rim electrocautery. This is believed to partially denervate the patella. However, there is no evidence of the efficacy of this procedure, nor do we know if it results in harm. A retrospective comparative cohort study was performed of 192 patients who had undergone a primary total knee replacement with the porous coated Low Contact Stress rotating platform prosthesis without patellar resurfacing between 2003 and 2007. In 98 patients circumferential electrocautery of the patellar rim was performed and in 94 patients it was not. The two groups were matched for gender and age. The general Oxford Knee Score and the more specific patellar score for anterior knee pain were used to assess patient outcomes a minimum of two years post-operatively. No statistically significant differences were noted between the groups for either scoring system (p = 0.41 and p = 0.87, respectively). Electrocautery of the patella rim did not improve the outcome scores after primary total knee replacement in our patients

Introduction. During revision surgery, the active electrode of an electrocautery device may get close to the implant, potentially provoking a flashover. Incidents have been reported, where in situ retained hip stems failed after isolated cup revision. Different sizes of discoloured areas, probably induced by electrocautery contact, were found at the starting point of the fracture. The effect of the flashover on the implant material is yet not fully understood. The aim of this study was to investigate the fatigue strength reduction of Ti-6Al-4V titanium alloy after electrocautery contact. Material and Methods. 16 titanium rods (Ti-6Al-4V, extra low interstitial elements, according to DIN 17851, ⊘ 5 mm, 120 mm length) were stress-relief annealed (normal atmosphere, holding temperature 622 °C, holding time 2 h) and cooled in air. An implant specific surface roughness was achieved by chemical and electrolytic polishing (Ra = 0.307, Rz = 1.910). Dry (n = 6) and wet (n = 6, 5 µl phosphate buffered saline) flashovers were applied with a hand-held electrode of a high-frequency generator (Aesculap AG, GN 640, monopolar cut mode, output power 300 W, modelled patient resistance 500 Ω). The size of the generated discoloured area on the rod's surface - representative for the heat affected zone (HAZ) - was determined using laser microscopy (VK-150x, Keyence, Japan). Rods without flashover (n = 4) served as control. The fatigue strength of the rods was determined under dynamic (10 Hz, load ratio R = 0.1), force-controlled four-point bending (FGB Steinbach GmbH, Germany) with swelling load (numerical bending stress 852 MPa with a bending moment of 17.8 Nm) until failure of the rods. The applied bending stress was estimated using a finite-element-model of a hip stem during stumbling. Metallurgical cuts were made to analyse the microstructure. Results. The control rods failed at the pushers of the setup (median: 94,550, range: 194,000 cycles). The rods with flashover failed directly at the HAZ significantly earlier than the control rods (p = 0.018). The analysis of the microstructure showed a transformation of the equiaxed α+β microstructure to a bimodal state. The size of the HAZs were equal for the dry (median: 1.51 mm. 2. , range: 5.68 mm. 2. ) and wet flashovers (median: 0.92 mm. 2. , range: 2.50 mm. 2. , p = 0.792). The cycles to failure were smaller for the dry flashover (median: 22,650 cycles, range: 5,700) than the wet flashover but not reaching statistical significance (median: 32,200, range: 57,900; p = 0.052). No correlation between the dimension of the HAZs and the cycles to failure was found (dry: r. 2. = 0.019, p = 0.8; wet: r. 2. = 0.015, p = 0.721). Discussion. Flashovers induced by an electrocautery device reduce the fatigue strength of Ti-6Al-4V. Since no correlation between the size of the HAZs and the cycles to failure was found, every contact between electrocautery devices and metal implants should be avoided. For any figures or tables, please contact authors directly

The purpose of the study was to determine how suture materials commonly used in arthroscopic surgery were affected by electrocautery. The effects of electrocautery were evaluated on four different suture materials commonly used in arthroscopic surgery; PDS, Ethibond, Orthocord and Fibrewire. Single suture strands were tied around two plastic rods immersed in a saline filled water bath at 37°C. Sutures were exposed to heat using the Mitek VAPR 3 electrosurgical unit and a corresponding side electrode. This was used on the high intensity vaporisation setting, at a power level of 240W. The electrode was applied directly to the suture strand, under tension, until the strand was completely burnt through. Fibrewire demonstrated a significantly higher burn through time in comparison to the other materials tested (83.30±38.69s, p< 0.001). Orthocord also demonstrated high heat tolerance (38.96±12.64s), which was significantly higher than both PDS (1.61±0.25s) and Ethibond (0.93s±0.06s) (p< 0.001). This is the first study to our knowledge assessing the tolerance of suture materials to electrocautery. This has important implications for the arthroscopic surgeon. On completion of an arthroscopic repair, the surgeon must always be extremely cautious, for fear of damaging the suture material and compromising their soft tissue repair. This study demonstrates that both Fibrewire and Orthocord can tolerate prolonged, direct heat application from electrocautery. We therefore conclude that short bursts of soft tissue vaporisation, after completing an arthroscopic repair with Fibrewire or Orthocord, are unlikely to have a detrimental effect on the suture material. However care should be exercised by the surgeon using Ethibond or PDS

Anterior knee pain post Total knee Replacement (TKR) has been reported to be as high as 49%. The source is poorly understood; both the peripatellar soft tissues and the infrapatellar fat pad have been implicated. Immunohistochemical studies demonstrate hyperinnervation of the peripatellar soft tissues. In theory circumferential electrocautery denervates the patella. However there is little evidence that this practice translates into improved clinical outcomes. This study aimed to find the effect on clinical outcome, of intraoperative circumpatellar electrocautery in patients undergoing TKR. 200 patients undergoing primary TKR were randomised to circumferential circumpatellar electrocautery or nothing. Patients were assessed for Visual (VAS) for anterior knee pain and Oxford Knee Score (OKS) preoperatively, 3 months, 6 months and 1 year post-procedure. Patients and assessors were blinded to treatment allocation until the end of the study. There were 91 patients in the electrocautery group and 94 controls. The mean VAS improvement from pre-op to one year was 3.8 in both groups. The mean improvement in OKS was 16.6 points in the control and 17.7 in the electrocautery group (p= 0.40). There were no significant differences between the two groups in terms of VAS or OKS at any other time. Although previous studies have conflicting outcomes, to our knowledge this is the first prospective randomised controlled blinded trial of significant power, to evaluate the effect of peripatellar diathermy in TKR. We conclude that denervation electrocautery of the patella makes no difference to the clinical outcomes of TKR

In the absence of patellar resurfacing, we have previously shown that the use of electrocautery around the margin of the patella improved the one-year clinical outcome of total knee replacement (TKR). In this prospective randomised study we compared the mean 3.7 year (1.1 to 4.2) clinical outcomes of 300 TKRs performed with and without electrocautery of the patellar rim: this is an update of a previous report. The overall prevalence of anterior knee pain was 32% (95% confidence intervals [CI] 26 to 39), and 26% (95% CI 18 to 35) in the intervention group compared with 38% (95% CI 29 to 48) in the control group (chi-squared test; p = 0.06). The overall prevalence of anterior knee pain remained unchanged between the one-year and 3.7 year follow-up (chi-squared test; p = 0.12). The mean total Western Ontario McMasters Universities Osteoarthritis Indices and the American Knee Society knee and function scores at 3.7 years’ follow-up were similar in the intervention and control groups (repeated measures analysis of variance p = 0.43, p = 0.09 and p = 0.59, respectively). There were no complications. A total of ten patients (intervention group three, control group seven) required secondary patellar resurfacing after the first year. Our study suggests that the improved clinical outcome with electrocautery denervation compared with no electrocautery is not maintained at a mean of 3.7 years’ follow-up. Cite this article: Bone Joint J 2014;96-B:473–8

INTRODUCTION. Due to increasing interest into taper corrosion observed primarily in hip arthroplasty devices with modular tapers, efforts towards characterizing the corrosion byproducts are prevalent in the literature [1–4]. As a result of this motivation, several studies postulate cellular induced corrosion due to the presence of remarkable features in the regions near taper junction regions and articulating surfaces [3–5]. Observations made on explanted devices from a retrieval database as well as laboratory tests have led to the alternative proposal of electrocautery-electrosurgery damage as the cause of these features. These surgical instruments are commonly used for hemostasis or different degrees of tissue dissection. METHODS. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to evaluate the features observed on retrieved devices. Retrieved devices consisted of OXINIUM and cobalt-chromium-molybdenum (CoCrMo) femoral implants, a Titanium-alloy hip stem, and a CoCrMo metal-on-metal femoral head. Electrocautery-electrosurgery damage was created using a SurgiStat II (Valleylab, Colorado) onto various components (CoCrMo, OXINIUM femoral heads as well as Ti-6Al-4V and CoCrMo alloy test stem constructs). Test components were evaluated using the same methods as the retrieved devices. RESULTS. Remarkable features were present on retrieved devices (Figure 1) which were similar to previous studies (3–5). The appearance of these features could be described as crater-like, pitted, scratched, molten or splattered material, and ruffled. These features were present on articulating and non-articulating regions as well as near taper junctions. Testing performed on samples using the SurgiStat II, created features that were similar in appearance (Figure 1). Additionally, material transfer that included an iron peak based on EDS in addition to the cobalt and chromium (present due to native material) was detected in the regions of contact (Figure 2). CONCLUSIONS. It was possible to re-create damage features similar to those previously characterized as remarkable features created by cellular-induced corrosion [3–5]. It is theorized that the high-voltage based electrocautery (commonly Bovie) or high-frequency based electrosurgical devices can result in localized degradation/alteration of oxides and passive regions of commonly used orthopaedic alloys. These surgical instruments, specifically the cutting electrodes, are frequently made of stainless steels which can result in iron transfer during contact with the device. During the surgical use of the electrocautery-electrosurgery instrument, it may be necessary to remove tissue, bone, or cauterize near the implant or explant which may have led to the damage features noted in this study and the previous literature [3–5]. If this damage occurs during the initial implantation of the devices, it may further exacerbate corrosion in the damaged region and/or alter the mechanical integrity of the constructs (i.e. fatigue performance)

Arthroscopic electrosurgical tools for ablative, desiccating or coagulative effect are delivered as monopolar or bipolar probes. Monopolar electrosurgery delivers various profiles of heat energy directly to the tissue within a non-conductive irrigant (such as water or glycine) whereas bipolar electrosurgery creates an energy source by producing an electrical arc between the bipolar electrodes on the instrument head within an electro-conductive irrigation solution (saline) - and the heat generated is then transferred to the target tissues. This study investigated the heat generation within the simulated in-vitro test model to review the level of local heat production and potential local tissue heat.

In a simulated In-vitro testing environment the local heat generation using bipolar or monopolar electrosurgical probes at standard power setting in either saline or water was tested, both touching and not touching a simulated tissue target, and for variable on-times.

Monopolar generated relatively little heat when used in water and not touching the tissue. By contrast the bipolar wand generated potentially damaging local tissue temperature rises when used in saline and not touching the tissue. Both probes generated high local tissue heat when touching the tissue in their recommended irrigation solution.

Monopolar electrosurgery delivered high localized temperature to the simulated tissue surface, but produced relatively little heat when not touching the tissue in a water solution. Bipolar however created high local temperature within the fluid adjacent to the probe irrespective if it was touching the tissue or not. Activation of the bipolar probe away from the tissue in saline irrigation may create a potential harmful temperature within the fluid medium without delivering therapeutic thermal effect to the target tissues. Monopolar electrosurgery appears to deliver a more controlled thermal effect, and only when in contact with the target tissues – potentially creating a reduced collateral thermal footprint.

Fracture of contemporary femoral stems is a rare occurrence. Earlier THR stems failed due to design issues or post manufacturing heat treatments that weakened the core metal. Our group identified and analyzed 4 contemporary fractured femoral stems after revision surgery in which electrochemical welds contributed to the failure. All four stems were proximally porous coated titanium alloy components. All failures occurred in the neck region post revision surgery in an acetabular cup exchange. All were men and obese. The fractures occurred at an average of 3.6 years post THR redo (range, 1.0–6.5 years) and 8.3 years post index surgery (range, 5.5–12.0 years). To demonstrate the effect of electrocautery on retained femoral stems following revision surgery, we applied intermittent electrosurgical currents at three intensities (30, 60, 90 watts) to the polished neck surface of a titanium alloy stem under dry conditions. At all power settings, visible discoloration and damage to the polished neck surface was observed. The localized patterns and altered metal surface features exhibited were like the electrosurgically-induced damage priorly reported. The neck regions of all components studied displayed extensive mechanical and/or electrocautery damage in the area of fracture initiation. The use of mechanical instruments and electrocautery was documented to remove tissues in all 4 cases. The combination of mechanical and electrocautery damage to the femoral neck and stem served as an initiation point and stress riser for subsequent fractures. The electrocautery and mechanical damage across the fracture site observed occurred iatrogenically during revision surgery. The notch effect, particularly in titanium alloys, due to mechanical and/or electrocautery damage, further reduced the fatigue strength at the fractured femoral necks. While electrocautery and mechanical dissection is often required during revision THA, these failures highlight the need for caution during this step of the procedure in cases where the femoral stem is retained

Introduction. Pitting damage on implants has been reported and attributed to use of electrocautery. This study aimed to distinguish how different TKA bearing surfaces are susceptible to this type of damage and whether surgeons were aware that this damage can occur. Methods. A survey was sent to Hip and Knee Society members to determine what percentage of adult reconstructive surgeons use electrocautery after implantation of components. Three bearing surfaces for primary TKA were selected: CoCr, Oxinium, and zirconium nitride (ZrN) to be damaged by electrocautery with a monopolar (MP, Bovie) and bipolar (BP, Aquamantys) electrocautery with three different energy settings. A comparison of surface damage and backscatter elemental analysis using SEM was performed. Average roughness (Ra), maximal peak-to-valley height (Rz,), kurtosis (Rk), and skewness (Rsk) measurements were collected using a profilometer (DektakXT, Bruker, Tucson, AZ) with a 2.5µm radius stylus to assess an area of 3.8mm by 3.2mm in the central portion of the area for each MP and BP energy setting used to impart damage to the bearing surfaces. A similar undamaged area for each bearing surface was also measured for roughness parameter comparison. Results. Median Rz and Ra measurements were larger for BP damaged areas compared to MP for all bearing surfaces.(Table 1) The Oxinium surface had the greatest increase in roughness parameters of all three bearing surfaces tested. Survey results indicate that a significant percentage of adult reconstructive surgeons use the electrocautery after implants are in place and are not aware of this type of damage. Backscatter SEM analysis found significant changes for BP damage compared to MP. Conclusion. Our in vitro study determined surface damage caused by electrocautery can have significant effects on the bearing surfaces of implants. Our survey determined many arthroplasty experts are unaware that this damage can occur. For any figures or tables, please contact the authors directly

Recently, a special type of surface pitting found on metal implants was proposed to arise from “inflammatory cell-induced” corrosion (ICI, Figure 1) (1, 2). The actual mechanism of this was unknown, but similar features were suggested to be artefacts of electrocautery damage from revision surgery (3). Under lab conditions and without the influence of any cells, we aimed to reproduce the same surface pits and structures with electrocautery. Methods. A polished cobalt-chromium disk (40 mm diameter, 8 mm thick) was marked into 8 sections for various testing conditions (Figure 2a). A stainless steel Bovie tip with a unipolar electrocautery machine (SYSTEM 5000, ConMed, USA) was used at typical surgical coagulation conditions: (70 volt, 120 watts, 562 KHz frequency). We mimicked three types of surgical techniques with the electrocautery: “Dotting” was repeated, on and off, direct surface contact; “Dragging” was constant, direct surface contact; “Hovering” was pausing several millimeters above the surface. We also examined the interplay of these practices on diamond-tip-induced scratches and either dry or wet (normal saline) conditions. High magnification images (Keyence VHX-2000E) were taken after the disk was cleaned with laboratory soap, light mechanical scrubbing, and formalin soak. Results. Coagulation mode generated electrical sparks when dotting/dragging and electrical arcs when hovering. These left seared marks that persisted even after cleaning (Figure 2b). At higher magnification, the surface features were comparable in size and shape to those attributed to ICI (1, 2). Areas wet with saline (Figure 3a) showed an abundance of ringed pits with raised edges that closely resembled those observed in Figure 1. Furthermore we obtained images similar to the phenomenon of “cellular tracks” (Figure 3b) (1). Premade scratches did not influence the pit arrangement but scratches made by the Bovie tip produced the characteristic scratch-associated ICI features as observed on implant retrievals in the past (Figure 3c) (4). Discussion. In the absence of cells, pitting equivalent to proposed ICI features was successfully replicated using an electrocautery in coagulation mode. Previously (4), we found a high incidence but small surface area of these features on the majority of retrievals, predominantly located in a focal area of the superior aspect of the femoral ball next to the junction of the stem. There were fewer on the inferior aspect which is consistent with electocautery damage when dissecting the hip capsule. The effect of this damage on retained parts is unknown, but electrocautery damage around areas of implant fractures has been reported (3). Conclusion. The striking similarities of the recreated pit structures imaged here suggest that the noted features of “inflammatory cell induced corrosion” were artefacts of the electrocautery during revision surgery. Future implant retrieval analysis should acknowledge these structures are not related to any particular mode of failure but should check for them around implant fracture sites

Aims. The worldwide COVID-19 pandemic is directly impacting the field of orthopaedic surgery and traumatology with postponed operations, changed status of planned elective surgeries and acute emergencies in patients with unknown infection status. To this point, Germany's COVID-19 infection numbers and death rate have been lower than those of many other nations. Methods. This article summarizes the current regimen used in the field of orthopaedics in Germany during the COVID-19 pandemic. Internal university clinic guidelines, latest research results, expert consensus, and clinical experiences were combined in this article guideline. Results. Every patient, with and without symptoms, should be screened for COVID-19 before hospital admission. Patients should be assigned to three groups (infection status unknown, confirmed, or negative). Patients with unknown infection status should be considered as infectious. Dependent of the infection status and acuity of the symptoms, patients are assigned to a COVID-19-free or affected zone of the hospital. Isolation, hand hygiene, and personal protective equipment is essential. Hospital personnel directly involved in the care of COVID-19 patients should be tested on a weekly basis independently of the presence of clinical symptoms, staff in the COVID-19-free zone on a biweekly basis. Class 1a operation rooms with laminar air flow and negative pressure are preferred for surgery in COVID-19 patients. Electrocautery should only be utilized with a smoke suction system. In cases of unavoidable elective surgery, a self-imposed quarantine of 14 days is recommended prior to hospital admission. Conclusion. During the current COVID-19 pandemic, orthopaedic patients admitted to the hospital should be treated based on an interdisciplinary algorithm, strictly separating infectious and non-infectious cases. Cite this article: Bone Joint Open 2020;1-6:309–315

The battle of revision TKA is won or lost with safe, effective, and minimally bony-destructive implant removal, protecting all ligamentous stabilisers of the knee and, most importantly, the extensor mechanism. For exposure, incisions should be long and generous to allow adequate access. A standard medial parapatellar capsular arthrotomy is preferred. A synovectomy is performed followed by debridement of all scar tissue, especially in the medial and lateral gutters. All peripatellar scar tissue is excised followed by release of scar tissue within the patellar tendon, allowing for displacement or everting of the patella. As patellar tendon avulsion at any time of knee surgery yields disastrous results, the surgeon should be continuously evaluating the patellar tendon integrity, especially while displacing/everting the patella and bringing the knee into flexion. If displacement/eversion is difficult, consider rectis-snip, V-Y quadricepsplasty, or tibial tubercle osteotomy. The long-held requisite for patellar eversion prior to component removal is inaccurate. In most cases simple lateral patellar subluxation will provide adequate exposure. If a modular tibial system is involved, removal of the tibial polyethylene will decompress the knee, allowing for easier access to patellar, femoral, and tibial components. For patellar component removal, first identify the border of the patella, then carefully clean and debride the interface, preferably with electrocautery. If the tibial component is cemented all-polyethylene, remove using an oscillating saw at the prosthetic-bone interface. Debride the remaining cement with hand tools, ultrasonic tools, or burrs. Remove the remaining peg using a low-speed burr. If the tibial component is metal-backed, then utilise a thin saw blade or reciprocating saw to negotiate the undersurface of the component between the pegs. If pegs are peripherally located, cut with a diamond disc circular cutting tool. Use a trephine to remove the pegs. For femoral component removal, identify the prosthetic-bone/prosthetic-cement interface then remove soft tissue from the interface, preferably with electrocautery. Disrupt the interface around all aspects of the component, using any of following: Gigli saw for cementless components only, micro saw, standard oscillating saw, reciprocating saw, a series of thin osteotomes, or ultrasonic equipment. If the femoral component is stemmed, remove the component in two segments using an appropriate screwdriver to remove the screw locking the stem to the component. Remove the femoral component with a retrodriver or femoral component extractor. Debride cement with hand tools or burr, using care to avoid bone fracture. If a stem is present, then remove with the appropriate extraction device. If “mismatch” exists, where femoral (or likewise, tibial) boss is smaller in diameter than the stem, creating a cement block prohibiting stem removal, remove the cement with hand tools or burr. If the stem is cemented, use hand tools, ultrasonic tools, or a burr to debride the cement. Curette and clean the canals. For tibial component removal, disrupt the prosthetic-cement/prosthetic-bone interface using an oscillating or reciprocating saw. Gently remove the tibial component with a retrodriver or tibial extractor. If stem extensions are utilised, disengage and debride all proximal cement prior to removing the stem. If stem is present, then remove stem with appropriate extraction device. If stem is grit-blasted and well-fixed, create 8mm burr holes 1.5 to 2.5cm distal to tibial tray on medial aspect and a small divot using burr, then drive implant proximally with Anspach punch. Alternatively, a tibial tubercle osteotomy may be performed. If the stem is cemented, use hand tools, ultrasonic tools or burr to debride cement

INTRODUCTION: Patients undergoing total knee arthroplasty may experience significant blood loss and are at risk of receiving blood transfusions. A bipolar sealing device designed to reduce intraoperative and postoperative blood loss, was compared to conventional electrocautery to determine its efficacy in maintaining hemoglobin levels and reducing transfusions in minimally invasive unilateral total knee arthroplasty. METHODS: A retrospective, matched control review of one hundred patients undergoing primary total knee arthroplasty by a single surgeon. Conventional electrocautery was used for hemostasis in 50 patients and bipolar sealing technology used in another 50 patients. RESULTS: Patients in the bipolar sealing group had a significantly lower mean decline in hemoglobin compared to the control group (3.3 ± 1.1 g/dL vs. 3.9 ± 1.2 g/dL; p = 0.0085). The prevalence of autologous transfusion was significantly lower for the bipolar sealing group (16%) compared to the controls (44%) (p < 0.001). The prevalence of allogeneic transfusion was also significantly lower for the bipolar sealing group (8%) compared to control group (22%) (p < 0.001). The prevalence of transfusion as a whole was significantly reduced by 64 percent (p < 0.001). While not statistically significant the break through allogeneic transfusion rate was reduced by 75 percent (4 controls compared to 1 treatment). DISCUSSION/CONCLUSION: The use of bipolar sealing technology in patients undergoing minimally invasive primary unilateral total knee arthroplasty is associated with a significant reduction in blood loss and transfusion rates compared to the use of conventional electrocautery. No funds were received in support of this study

Background: Authors used a new bipolar sealer system (TissueLink Medical Inc., Dover, New Hampshire) for electrocoagulation in major orthopaedic surgery such as total hip and knee arthroplasty and spinal surgery. The bipolar sealer is an electrosurgical device which delivers radiofrequency energy to saline for haemostatic sealing and coagulation of soft tissue at the operative site providing haemostasis at much lower temperatures than conventional electrocautery (< 100°C). Materials and Methods: Since October 2004 through June 2007 the authors conducted a randomized study on 800 patients – total hip or Knee arthroplasty or spinal surgery–to compare the clinical outcomes in two groups. In the study cohort the bipolar sealer device was used, in the matching group conventional electrocautery. Both cohorts were evaluated for intraoperative blood loss, transfusion rate, postoperative drainage, number of transfusions and haemoglobin levels. Patients with known coagulation and peripheral circulation disorders were excluded. No preoperative autologous blood donation was utilized. Results: All patients recovered without complications and no re-operations became necessary in both groups. A significant reduction in post-operative and total blood loss (p=0.05 and p=0.02, respectively) occurred, as well as absence of tissue charring and smoke production in the bipolar sealer group. The mean decline in haemoglobin was significantly lower for the treatment group compared to the control group. The allogenic blood transfusion rates were extremely low in both groups (4.4% control vs. 0% treatment group). The mean volume of post-operative drainage was 451 milliliters (range, 1500 to 815 milliliters) for the standard electrocautery group and 256 milliliters (range, 0 to 743 milliliters) for the bipolar sealer group (p=0.002). Discusssion and conclusion: Results suggest that use of this bipolar sealing device is at least as effective as standard cautery devices and may reduce blood loss, tissue damage and smoke production in major orthopaedic surgery without affecting outcome. Lesser bleeding results in faster recovery of the patient, better wound healing and lower complication rates

Introduction. Previous studies of CoCr alloy femoral components for total knee arthroplasty (TKA) have identified 3. rd. body abrasive wear, and apparent inflammatory cell induced corrosion (ICIC) [1] as potential damage mechanisms. The association between observed surface damage on the femoral condyle and metal ion release into the surrounding tissues is currently unclear. The purpose of this study was to investigate the damage on the bearing surface in TKA femoral components recovered at autopsy and compare the damage to the metal ion concentrations in the synovial fluid. Methods. 12 autopsy TKA CoCr femoral components were collected as part of a multi-institutional orthopedic implant retrieval program. The autopsy components included Depuy Synthes Sigma Mobile Bearing (n=1) and PFC (n=1), Stryker Triathlon (n=1) and Scorpio (n=3), and Zimmer Nexgen (n=4) and Natural Knee (n=2). Fluoro scans of all specimens prior to removal was carried out to assure no signs of osteolysis or aseptic loosening were present. Third-body abrasive wear of CoCr was evaluated using a semi-quantitative scoring method similar to the Hood method [2]. ICIC damage was reported as location of affected area and confirmed using a digital optical microscope with 4000X magnification. Synovial fluid was aspirated from the joint capsule prior to removal of the TKA device. The synovial fluid was spun at 1600 rpm for 20 minutes in a centrifuge with the cell pellet removed. The supernatant was analyzed in 1 mL quantities for ICP-MS (inductively coupled plasma mass spectrometry) by Huffman Hazen Laboratories. Data was expressed as ppb. Results. Mild to severe damage (Damage Score ≥ 2) was observed on 92% of the components in at least one quadrant, with no severe damage (Damage Score = 4) observed. ICIC damage was observed on three components in three different regions (the posterior lateral, anterior, and medial bearing surface). These observations were confirmed with digital optical microscopy, where we observed as interconnecting pits and indentations with a spiraling or trailing region, consistent with prior observation of ICIC in retrievals (Figure 1). Cobalt was detected in 7 cases, however the metal levels were not as high as levels observed in patients with a failed joint replacement (Table 1). There was no correlation between the metal ion concentration and the damage score on the CoCr femoral condyle. Discussion. This study documents the damage mechanics and associated metallic release into the synovial fluid of “well-functioning” TKA components retrieved at autopsy. It has been suggested that ICIC damage is actually damage from electrocautery during surgery. However, we observed ICIC damage on autopsy retrievals in which the use of electrocautery is unlikely. The damage mechanisms observed on the autopsy TKA components were similar but less severe compared to mechanisms observed in long-term TKA components from revision surgery [1]. More research is needed to better understand the metal release from CoCr femoral components and periprosthetic tissue reactions in TKA

The verification of the alignment of the lower limb is critical for reconstructive surgery as well as trauma surgery in order to prevent osteoarthritis. The mechanical axis is a straight line defined by the center of the femoral head and the center of the ankle joint, ideally passing the knee joint in its center. Whereas the usual preoperative method to determine the mechanical axis of the lower limbs is still the long standing radiograph, common intra-operative methods are the use of an electrocautery cord or an X-ray grid consisting of wire lines underneath the patient. Both methods require the surgeon to bring the femoral head and the ankle joint exactly to overlay with a radiopaque line that passes through both points. The distance of the knee center from this line is defined as the mechanical axis deviation (MAD). In order to reduce the errors introduced by perspective projection effects, the joint centers must be placed in the center of the c-arm images, which definitely requires time, experience and additional radiation. We propose a computer aided X-ray stitching method that puts individual X-ray images into a panoramic image frame combining the Camera Augmented Mobile C-arm (CamC) system, which features a video camera with its optical center virtually coinciding with the origin of the X-rays, with an optical tracking marker pattern underneath the operating table. The camera image of the marker pattern is used to perform pose estimation of the C-arm, allowing the calculation of the x-ray source motion between the positions in which the individual X-rays were taken. By estimating the homography, the different X-rays can be registered into a panoramic frame, enabling perfect alignment and metric measurements. In order to reduce parallax effects that lead to axis and metric measurement errors, we applied a method requiring two constraints: The bone plane has to be roughly parallel to the planar marker pattern and the distance between the marker plane and the bone plane has to be estimated. In order to evaluate the method, we used a life-size synthetic skeleton leg. After tightening a straight wire between the centers of the hip and ankle joint, the knee joint was bent into a MAD of 55 mm, which was confirmed by measuring the distance between the knee center and the wire with a ruler. The leg phantom was then placed on a radiolucent operating table, parallel to the pattern plane 130 mm underneath. The operating table was moved through the C-arm while acquiring the three desired X-ray images. which were registered into a panoramic image frame. The centers of the femoral head, the ankle, and the knee were manually determined on the generated panoramic image by a surgeon. The mechanical axis was automatically displayed and the MAD was visualised in the image and computed as 55.23 mm. We presented a new solution to intra-operatively verify alignment of the lower extremity. When using the CamC system, only a marker pattern has to be used for tracking. No additional tracking devices and calibration procedures are needed. Furthermore, the presented method only requires three x-rays that cover the femoral head, the knee and the ankle and marking of the three spots. Due to the parallax correction, these spots do not have to be exactly in the center of the picture. For this reason, compared to using an X-ray grid or an electrocautery cord, our method allows the procedure to be much faster and reduces the number of x-ray images. However, for clinical evaluation, a patient study will be conducted in the future

Adequate soft tissue balance at the time of total knee arthroplasty (TKA) prevents early failure. In cases of varus deformity, once the medial osteophytes have been resected, a progressive release of the medial soft tissue sleeve (MSS) from the proximal medial tibia is needed to achieve balance. The “classic” medial soft tissue release technique, popularised by John Insall et al., consists of a sharp subperiosteal dissection from the proximal medial tibia that includes superficial and deep medial collateral ligament (MCL), semimembranosus tendon, posteromedial capsule, along with the pes anserinus tendons, if needed. However, this technique allows for little control over releases that selectively affect the flexion and extension gaps. When severe deformity is present, an extensive MSS release can cause iatrogenic medial instability and the need to use a constrained implant. It has been suggested that the MSS can be elongated by performing selective releases. This algorithmic approach includes the resection of the posterior osteophytes as the initial balancing gesture. If additional MSS release is necessary in extension, a subperiosteal release of the posterior aspect of the MSS is performed with electrocautery, detaching the posterior aspect of the deep MCL, posteromedial capsule and semimembranosus tendon for the proximal and medial tibia. Dissection is rarely extended more than 1.5 cm distal to the joint line. If additional release is necessary in extension, the medial compartment is tensioned with a laminar spreader and multiple needle punctures (generally less than 8) are performed in the taut portion of the MSS using an 18G or 16G needle. If additional release is necessary to balance the flexion gap, multiple needle punctures in the anterior aspect of the MSS are performed. This stepwise approach to releasing the MSS in a patient with a varus deformity allows the surgeon to target areas that selectively affect the flexion and extension gaps. Its use has resulted in diminished use of constrained TKA constructs and subsequent cost savings. We have not seen an increase in post-operative instability developing within the first post-operative year. We recommend caution when implementing this technique. Unlike the traditional release method, pie-crusting is likely technique-dependent and failure can occur within the MCL itself. Due to the critical importance of the MCL in knee stability, further research and continuous follow up of patients undergoing TKA with this technique are warranted. Intra-operative sensing technology may be useful to quantitate the effect of pie-crusting on the compartmental loads and overall knee balance

Deformity correction is a fundamental goal in total knee arthroplasty. Severe valgus deformities often present the surgeon with a complex challenge. These deformities are associated with abnormal bone anatomy, ligament laxity and soft tissue contractures. Distorted bone anatomy is due to bone loss on the lateral femoral condyle, especially posteriorly. To a lesser extent bone loss occurs from the lateral tibia plateau. The AP axis (Whiteside's Line) or epicondylar axis must be used as a rotational landmark in the severely valgus knee. Gap balancing techniques can be helpful in the severely valgus knee, but good extension balance must be obtained before setting femoral rotation with this technique. Coronal alignment is generally corrected to neutral or 2- to 3-degree overcorrection to mild mechanical varus to unload the attenuated medial ligaments. The goal of soft tissue releases is to obtain rectangular flexion and extension gaps. Soft tissue releases involve the IT band, posterolateral corner/arcuate complex, posterior capsule, LCL, and popliteus tendon. Assessment of which structures is made and then releases are performed. In general, pie crust release of the IT band is sufficient for mild deformity. More severe deformities require release of the posterolateral corner / arcuate and posterior capsule. I prefer a pie crust technique, while Ranawat has described the use of electrocautery to perform these posterior/ posterolateral releases. In most cases the LCL is not released, however, this can be released from the lateral epicondyle, if necessary. Good ligament balance can be obtained in most cases, however, some cases with severe medial ligament attenuation require additional ligament constraint such as a constrained condylar implant