Aim. Local antibiotics released through a carrier is a commonly used technique to prevent infection in orthopaedic procedures. An interesting carrier in aseptic bone reconstructive surgery are bone chips impregnated with AB solution. Systemically administered Cefazolin (CFZ) is used for surgical site infection prophylaxis however in vitro study showed that fresh frozen and processed bone chips impregnated with CFZ solution completely release the CFZ within a few hours. On the other hand irradiated freeze-dried bone chips, treated with supercritical CO2 (scCO2) have been shown to be an efficient carrier for the antibiotics vancomycine or tobramycine. With this pilot study we wanted to investigate if CFZ solution impregnation of bone chips treated with scCO2 shows a more favorable release pattern of CFZ. Method. The bone chips were prepared using the standard scCO2 protocol and were impregnated with 100 mg/ml cefazolin at different timepoints during the process: before freeze drying (BC type A), after freeze drying (BC type B) and after gamma-irradiation. 0.5g of the impregnated bone grafts were incubated with 5ml of fetal calf serum (FCS) at 37°C. At 2, 4, 6, 8 and 24h of incubation 200µl of eluate was taken for analysis. After 24h the remaining FCS was removed, bone grafts were washed and new FCS (5ml) was added. Consecutive eluate samples were taken at 48, 72 and 96h of incubation. The concentration of CFZ in the eluates was measured with the validated UPLC-DAD method. Analysis was performed in triplicate. Results. The mean concentration of CFZ in the eluate obtained from BC type A incubated for 2h was higher compared to BC type B, respectively 581 mg/l and 297 mg/l. However, the elution profile is the same for both types: the CFZ concentration in the eluates drops within the first 24h from 581 mg/l to 365 mg/l (37%) for BC type A and from 297 mg/l to 132 mg/l (56%) for BC type B. After 24h no further significant CFZ release is seen. Impregnation of the bone chips before or after gamma irradiation did not affect this elution profile. Conclusions. Bone chips treated with scCO2 show a comparable elution pattern compared to non-scCO2 treated bone chips. AB release depends on the properties of the AB, making it impossible to copy the same impregnation protocol for different antibiotics. The stability of CFZ in solution at 37°C and its release are a major concern when establishing an impregnation protocol with CFZ

ZrN-multilayer coating is clinically well established in total knee arthroplasty [1-3] and has demonstrated significant reduction in polyethylene wear and metal ion release [4,5]. The goal of our study was to analyze the biotribological behaviour of the ZrN-multilayer coating on a polished cobalt-chromium cemented hip stem. CoCr28Mo6 alloy hip stems with ZrN-multilayer coating (CoreHip®AS) were tested versus an un-coated version. In a worst-case-scenario the stems with ceramic heads have been tested in bovine serum in a severe cement interface debonding condition under a cyclic load of 3,875 N for 15 million cycles. After 1, 3, 5, 10 & 15 million cycles the surface texture was analysed by scanning-electron-microscopy (SEM) and energy-dispersive x-ray (EDX). Metal ion concentration of Co,Cr,Mo was measured by inductively coupled plasma mass spectroscopy (ICP-MS) after each test interval. Based on SEM/EDX analysis, it has been demonstrated that the ZrN-multilayer coating keeps his integrity over 15 million cycles of severe stem cemented interface debonding without any exposure of the CoCr28Mo6 substrate. The ZrN-multilayer coated polished cobalt-chromium cemented hip stem has shown a reduction of Co & Cr metal ion release by two orders of a magnitude, even under severe stem debonding and high interface micro-motion conditions. ZrN-multilayer coating on polished cobalt-chromium cemented hip stems might be a suitable option for further minimisation of Co & Cr metal ion release in total hip arthroplasty. Clinical evidence has to be proven during the next years

Introduction. Circumferential periosteal release is a rarely reported procedure for paediatric limb lengthening. The technique involves circumferential excision of a strip of periosteum from the metaphysis of the distal femur, tibia and fibula. This study aims to determine the mid to long-term effectiveness of this technique. Materials and Methods. A retrospective case series was performed of all patients undergoing circumferential periosteal release of the distal femur and/or tibia between 2006 and 2017. Data collected included demographics, surgical indication, post-operative limb-lengths and complications. Data collection was stopped if a further procedure was performed that may affect limb-length (except a further release). Leg-length discrepancies were calculated as absolute values and as percentages of the longer limb-length. Final absolute and percentage discrepancies were compared to initial discrepancies using a paired t-test. Results. Eighteen patients (11 males) were identified, who underwent 25 procedures. The mean age at first surgery was 5.83 (SD 3.49). The commonest indication was congenital limb deficiency (13 patients). In 23 procedures the periosteum was released in two limb segments (distal femur and distal tibia), whereas in two patients it was released in a single limb segment. Five patients underwent repeat periosteal release, and one patient had three periosteal releases. Mean follow-up was 63.1 months (SD 33.9). Fifteen patients had sufficient data for statistical analysis. The mean initial absolute discrepancy was 2.01cm (SD 1.13), and the mean initial percentage discrepancy was 4.09% (SD 2.76). The mean final absolute discrepancy was 1.00cm (SD 1.62), and the mean percentage final discrepancy was 1.37% (SD 2.42). The mean reduction in absolute discrepancy was 0.52 cm (95%CI −0.04–1.08; p=0.068, paired t-test), and the mean reduction in percentage discrepancy was 2.00% (95% CI 1.02–2.98, p=<0.001 paired t-test). In five patients the operated limb overgrew the shorter limb. Conclusions. Circumferential periosteal release produces a modest decrease in both absolute and percentage limb-length discrepancy, although the outcome is variable and some patients may experience overgrowth of the operated limb

Background. Intraoperative balancing of total knee arthroplasty (TKA) can be accomplished by either more prevalent but less predictable soft tissue releases, implant realignment through adjustments of bone resection or a combination of both. Robotic TKA allows for quantifiable precision performing bone resections for implant realignment within acceptable final component and limb alignments. Objective. To provide a direct comparison of patient reported outcomes between implant realignment and traditional ligamentous release for soft tissue balancing in TKA. Methods. IRB approved retrospective single surgeon cohort study of prospectively collected operative and clinical data of consecutive patients that underwent TKA with a single radius design utilizing kinematic sensors to assess final balance with or without robotic assistance allowing for a minimum of 12 months clinical follow up. Operative reports were reviewed to characterize the balancing strategy. In surgical cases using robotic assistance, pre-operative plan changes that altered implant placement were included in the implant realignment group. Any patient that underwent both implant realignment and soft tissue releases was analyzed separately. Kinematic sensor data was utilized to quantify ultimate balance to assure that each cohort had equivalent balance. Patient reported outcome data consisting of Knee Society- Knee Scores (KS-KS), Knee Society- Function Scores (KS-FS), and Forgotten Joint Scores (FJS) were prospectively collected during clinical follow up. Results. 182 TKA were included in the study. 3-Month clinical follow up was available for 174/182 knees (91%), 1-Year clinical follow up was available for 167/182 knees (92%) and kinematic sensor data was available for 169/182 knees (93%). Kinetic sensor data showed that on average all of the balancing subgroups achieved clinically equivalent balance. Use of robotic-arm assistance provided the tools and confidence to decrease from ligament release only in 40.8% of non-robotic cases to 3.8% in the robotic group, and the use of component realignment alone increased from 23.7% in the non-robotic cases to 48.1% in the robotic TKA group. KS-KS, KS-FS and FJS scores showed improvements in outcomes at both the 3-month and 1-year time points in the implant realignment cohort compared to the ligamentous release cohort. KS-KS, KS-FS, and FJS at 1-year were 1.6, 7.6, and 17.2 points higher respectively. While none of the comparisons reached statistical significance, KS-FS at 1 year showed a statistically and clinically significant difference (MCID 6.1–6.4) increase of 7.7 points in the implant realignment cohort compared to the ligamentous cohort. The 1-year trend can be further explained by the outperformance (MCID increase of 6.4 points) of the implant realignment robotic cohort at 1-year compared to the non-robotic ligamentous cohort. Conclusions. Directly comparing TKA patients balanced with implant realignment alone versus ligamentous release alone versus combined technique, a trend toward clinical improvement above a minimally clinical significant difference in KS-FS scores benefiting the implant realignment technique was seen at both 3-months and 1-year post-operatively. We hypothesize that the benefit of implant realignment is achieved through decreased soft tissue trauma as well as potentially greater predictability and sustainability of soft tissue balance than with soft tissue releases alone

Aim. Allograft bone chips used in complex bone reconstruction procedures are associated with an increased infection risk. The perioperative use of systemic cefazolin is standard to prevent infection, but is less effective in the presence of avascular bone grafts. Bone chips have been described as a carrier for local delivery of antibiotics, but impregnation with cefazolin in a prophylactic setting has not been described. We aimed to obtain a prolonged cefazolin release from bone chips to maximize the prophylactic effect. Method. Three types of bone chips were evaluated: fresh frozen, decellularized frozen and decellularized lyophilized. Bone chips were incubated with 20 mg/ml cefazolin or treated with liquid hydrogel containing either 1 mg/ml fibrin or 1 mg/ml collagen and 20 mg/ml cefazolin. The cefazolin hydrogel was distributed in the porous structure by short vacuum treatment. Bone chips with cefazolin but without hydrogel were incubated for 20 min- 4h under atmospheric pressure or under vacuum. Cefazolin elution of bone chips was carried out in fetal bovine serum and analyzed by Ultra Performance Liquid Chromatography – Diode Array Detection. Results. Without hydrogel, cefazolin release was limited to 4 hours. When vacuum was applied during impregnation, elution of cefazolin exceeding the MIC (minimal inhibitory concentration) from decellularized lyophilized bone chips was obtained for 36 hours. Use of a collagen hydrogel and vacuum treatment resulted in a high concentration at 24 hours, but did not support prolonged release for any of the three types of tested bone chips. In contrast, combination of decellularized frozen bone chips with fibrin hydrogel resulted in an initial release of 533 μg/ml, declining to the MIC at 72 hours, while no longer measurable after 92 hours. Such elution profile is desirable, since high initial levels are important to maximize antibacterial action whereas the complete wash out prevents antibiotic resistance. By increasing the cefazolin concentration during impregnation, elution above the MIC could be obtained for 120 hours. Impregnated bone chips stored at −20° C for 3 months performed similarly to freshly impregnated bone chips. Conclusions. Bone chips processed with the described hydrogel-based impregnation protocol allows tunable delivery of cefazolin for a local prophylactic effect

The direct anterior (DA) approach for total hip arthroplasty (THA) has become increasingly popular in North America. With experience, exposure of both the acetabulum and femur can be achieved similar to those in other approaches. In cases of difficult femoral exposure, the conjoint tendon of the short external rotators can be released to improve visualisation. The effect of conjoint tendon release has not been previously explored in regards to overall outcomes, or postoperative pain. The goal of this study was to evaluate 1) the length of stay and inpatient pain medication requirements of patients undergoing DA THA on the basis of conjoint tendon release, and 2) whether conjoint tendon release influenced functional outcomes. We conducted a retrospective chart review of all cases of primary DA THAs conducted by single surgeon at LHSC University between August 2012 and July 2015. Patient demographics, bilateral THA cases, intraoperative conjoint tendon or other soft tissue releases, intra-operative complications, and length of stay (LOS) were evaluated for all cases. Inpatient pain medication data was available for all cases from Apr 2014 onwards. One year functional outcome scores, including WOMAC and Harris Hip Scores (HHS), were evaluated for all cases before August 2014. Six-week and three-month functional outcome scores were available and evaluated for a subset of cases. All data was analysed with multiple linear regression. Three hundred and twelve cases of primary DA THAs were identified, of which 29 were concurrent bilateral THAs. One hundred and eighty cases included a conjoint tendon release, while 29 cases had other soft tissue releases (tensor fascia lata). Mean age and BMI were 64.9±11.5 years and 29.0±5.3 respectively. Mean LOS was 1.3±1.1 days, with age, bilateral THA, non-conjoint tendon soft tissue release, and intra-operative complications being predictive of LOS (p<0.05). Pain medication data was available for 107 cases, of which 11 were concurrent bilateral THAs. Sixty four cases included a conjoint tendon release, while one case had other soft tissue releases. Mean daily morphine equivalent dose (MED) narcotic use was 43.2±48.2mg, with age being a negative predictor of narcotic use (p<0.05). BMI was a negative predictor of one year HHS pain, HHS total, and all WOMAC subcategory scores, while age was a negative predictor of one year HHS function and HHS total scores (p<0.05). None of the variables were predictive of six-week and three-month functional outcome scores. Conjoint tendon release was not predictive of LOS, inpatient pain medication requirements, or outcome scores. Conjoint tendon release did not affect postoperative pain, LOS, or functional outcomes. Given that conjoint release improves femoral exposure, intraoperative thresholds for conjoint release should be low. The effect of intraoperative release of other soft tissues is uncertain, as this increased LOS but not postoperative pain

Introduction. In total knee arthroplasty (TKA) the knee may be found to be too stiff in extension, causing a flexion contracture. One proposed surgical technique to correct this extension deficit is to recut the distal femur, but that may lead to excessively raising the joint line. Alternatively, full extension may be gained by stripping the posterior capsule from its femoral attachment, however if this release has an adverse impact on anterior-posterior (AP) stability of the implanted knee then it may be advisable to avoid this technique. The aim of the study was therefore to investigate the effect of posterior capsular release on AP stability in TKA, and compare this to the restraint from the cruciate ligaments and different TKA inserts. Methods. Eight cadaveric knees were mounted in a six degree of freedom testing rig (Fig.1) and tested at 0°, 30°, 60° and 90° flexion with ±150 N AP force, with and without a 710 N axial compressive load. The rig allowed an AP drawer to be applied to the tibia at a fixed angle of flexion, whilst the other degrees-of-freedom were unconstrained and free to translate/ rotate. After the native knee was tested with and without the anterior cruciate ligament (ACL), a cruciate-retaining TKA (Legion; Smith & Nephew) was implanted and the tests repeated. The following stages were then performed: replacing with a deep dished insert, cutting the posterior cruciate ligament (PCL), releasing the posterior capsule using an osteotome (Fig. 2), replacing with a posterior-stabilised implant and finally using a more-constrained insert. Results. In anterior drawer, only cutting the ACL caused a large increase in laxity compared to the native state (8 mm average across all flexion angles). At 0°, releasing the posterior capsule increased the laxity by 1.4 mm compared with cutting the PCL (p < 0.05), with no significance found at any other flexion angles. In posterior drawer with no compressive load, cutting the PCL significantly increased laxity at 30°, 60° and 90° (average 7 mm), however additional release of the posterior capsule only increased laxity by 1.5 mm and 0.8 mm at 0° and 30° respectively. At 30°, 60° and 90°, posterior stability was significantly restored by introducing a posterior-stabilised or more-constrained insert. When a 710 N compressive load was applied. Conclusions. The most important finding of the study was that releasing the posterior capsule did not cause a clinically large difference in AP laxity in context with cutting the PCL. Therefore, releasing the posterior capsule to restore extension during TKA surgery could be considered a biomechanically safe option. In cases of posterior instability due to PCL and capsular damage, a posterior-stabilised insert can restore stability, particularly in mid to late flexion. Future studies could compare this data to isolated implant constraints, to help investigate how much stability is provided by the different implant geometries compared to the PCL and posterior capsule

Introduction. W. ide . A. wake . L. ocal . A. naesthetic . N. o . T. ourniquet (WALANT) is a well- established day case procedure for carpal tunnel release with several advantages and enhanced post-operative recovery. Use of Local anaesthesia with Adrenaline using a 27G needle allows a bloodless field and distraction techniques achieve patient comfort during the procedure. Objectives. This retrospective, observational cohort study assesses patient satisfaction and undertakes functional evaluation using the validated Boston Carpal Tunnel Questionnaire (BCTQ) following WALANT technique for carpal tunnel release (CTR). The BCTQ has a symptom severity scale based on 11 items and a functional status scale of 8 elements. Further we compare surgical outcomes between techniques of WALANT and traditional CTR. Patient and Methods. We included 30 consecutive patients, 15 in each arm who either underwent traditional CTR with the use of Tourniquet or with the WALANTtechnique. Data was collected from Electronic Patient Records and hand therapy assessments. A satisfaction questionnaire and Visual Analogue Score (VAS) was utilized to evaluate subjective outcomes. Functional outcomes was assessed by BCTQ scoring system and clinical review. Microsoft Excel was used for analysis. Results. 100% of patients in the WALANT group stated they were satisfied with the operation. Relief from night pain and sleep disturbance were the most improved symptoms. BCTQ and clinical assessment evaluation between both groups revealed comparable results with no significant difference. Conclusion. With advantages of no tourniquet related pain, increased patient satisfaction and functional outcomes on the BCTQ scores, WALANT technique has the potential to be the standard technique for CTR

Total knee arthroplasty has been the main treatment method among advanced osteoarthritis (OA) patients. The main post-operative evaluation considers the level of pain, stability and range of motion (ROM). The knee flexion level is one of the most important categories in the total knee arthroplasty patient's satisfaction in Asian countries due to consistent habits of floor-sitting, squating, kneeling and cross legged sitting. In this study, we discovered that the posterior capsular release enabled the further flexion angles by 14 degrees compared to the average ROM without posterior release group. Our objective was to increase the ROM using the conventional total knee arthroplasty by the posterior capsular release. Posterior capsular release is being used in order to manage the flexion contraction. Although the high flexion method extends the contact area during flexion by extending the posterior condyle by 2mm, the main problem has been the early femoral loosening. We searched for the method to get the deep knee flexion with the conventional knee prosthesis. 122 OA patients with less than preoperative 130 flexion that underwent conventional TKAs using Nexgen from January, 2014 to September, 2016 were reviewed. Posterior femoral osteophytes were removed as much as possible, but 74 cases were performed posterior capsular release, while 48 cases were not performed. After checking postoperative ROM after 6 months of operation, we compared 74 knees with a posterior capsular release and 48 knees without posterior capsular release. As a result, the average ROM in the posterior capsular release group was 132 degrees, but the average ROM without posterior release group is 118 degrees. No postoperative hyperextension was found when the adequate size of polyethylene (PE) thickness was utilized. Hence, the conventional TKA with a posterior capsular release showed satisfactory clinical outcomes in the deep knee flexion of Asians

Introduction. The purpose of the study was to assess the clinical outcomes of an algorithm for soft tissue femoral release in anterior approach (AA) total hip arthroplasty (THA). Specifically, the following were assessed in this series of patients utilizing a standardized soft tissue release sequence: 1) clinical outcomes with the Harris Hip Score (HHS); 2) re-operation rates; 3) component survivorship; and 4) complications. Methods. We retrospectively analyzed a prospectively maintained database of patients who underwent AA THA from 2014 to 2017. A total of 1000 patients were included, with minimum follow up of 2 years (range 2–5 years). The mean age was 65 years (range, 22–89), 48% were males, and the mean Body Mass Index was 34 (range, 20–52). Descriptive statistics were performed for most endpoints except for component survivorship, which was assessed with Kaplan-Meier analysis. Result. There was 95% follow-up (54 patients lost to follow-up). The HHS improved from mean 56 preoperatively (range, 34–78) to mean 88 post-operatively (range, 65–100) (p<0.01). There were three complications: one superficial wound dehiscence which resolved with outpatient secondary operative wound closure; one calcar fracture managed non-operatively; and one anterior hip dislocation managed with closed reduction. There were no cases of component loosening, deep infection, prosthetic joint infection, or death. All components demonstrated survivorship. Conclusion. Using an algorithmic AA THA technique to address the femoral soft tissue release may offer acceptable outcomes and complication rates. Further study of this technique is warranted utilizing data from multiple surgeons to ensure that findings in this study are generalizable. For any figures or tables, please contact authors directly

Introduction. Metal-on-metal bearings (MoM) have been reported to release metal ions that are potentially leading to adverse tissue reactions. Alternatively, ceramic-on-ceramic bearings (CoC) are an attractive treatment for young and active patients and composite materials like zirconia toughened alumina (ZTA) have been successfully introduced clinically. One of the most common ZTA-material in CoC is the Biolox® delta, manufactured by Ceramtec. Along with alumina and zirconia, this material also contains traces of chromium, strontium and yttrium. The aim of this study was to analyse the ion release for these materials clinically as well as experimentally. Material and Methods. Within a clinical trial, three different patient groups were compared: a) a control group without any implants, b) patients, three months after unilateral treatment with Biolox® delta CoC and c) patients, twelve months after unilateral treatment with Biolox® delta CoC. Whole-blood samples were collected and analysed in regards to the trace elements using high-resolution-ICP-MS. In the experimental setup, the leaching behaviour of five Biolox® delta ceramic heads and five CoCr-heads was analysed. The heads were immersed in serum for seven days at 37°C. The ion-release of aluminium, zirconium, cobalt, chromium, strontium and yttrium were detected based on high-resolution-ICP-MS. Results. In the patient groups, most elements remained below their specific limit of detection (LoD), except for aluminium and strontium. For aluminium, the values of the control and the twelve- month group were below the LoD (27.2µg/L) and the three month values were only slightly increased (median: 34.2µg/L). For strontium median values of 39.7µg/L were found in the control group which were higher after three month (79.6µg/L) and returned to 41.1 µg/L after twelve months. However, this difference was not statistically significant. The leaching experiments showed that high amounts of cobalt (177.3µg/L) and chromium (4.2µg/L) were released from the metallic heads, which was not seen in the ceramic material. Similar to the patient control group, a seemingly high background-concentration of strontium was found in the serum (98.3µg/L) which was only slightly increased by the ceramic material (107.7µg/L). Discussion and Conclusion. The current study revealed that there was no significant increase of any analysed material or trace elements in the target patients treated with CoC bearings. The clinical trial also showed that strontium is a trace element that exists in the human body regardless of the presence or absence of an implant. However, with MoM high values of cobalt were released. As this release occurred even without any joint articulation, as shown in the experiments, surface corrosion seems to be a relevant mechanism in the ion release of MoM. A limitation of the study is that different patient groups were compared within the clinical trial

Background. Intraoperative balancing can be accomplished by either more prevalent but less predictable soft tissue releases, implant realignment through adjustments of bone resection or a combination of both. There is no published study directly comparing these methods. Objective. To provide a direct comparison between implant realignment and traditional ligamentous release for soft tissue balancing in total knee arthroplasty using both objective kinematic sensor data to document final balance and patient reported outcomes. Methods. IRB Approved retrospective cohort study of prospectively collected data comparing kinematic sensor data and patient reported outcomes for all consecutive patients that underwent TKA utilizing kinematic sensors with or without robotic assistance performed between August 2012 to April 2017 to allow for a minimum of 12 months clinical follow up. Results. 107 knees met inclusion criteria. Component realignment was utilized more frequently in the robotic surgical technique cohort than the non-robotic, non-navigated cohort due to the increased precision in implant realignment possble. Although KSS and FJS scores showed equivalent outcomes at both the 3-month and 1-year time points, KSS-Function scores at 1-year showed a statistically and clinically significant increase of 11.89 points in the implant realignment cohort compared to the ligamentous release cohort. Conclusions. A statistically and clinically significant improvement in KSS-Function scores benefiting the implant realignment technique was seen at 1-year post-operatively. This may suggest a benefit to using implant realignment as the ideal balancing strategy in total knee arthroplasty. Further longitudinal studies with increased number of cases should increase statistical power which is needed to further confirm the suggested benefits of the implant realignment balancing technique

The extent of soft-tissue release and the exact structures that need to be released to correct deformity and balance the knee has been a controversial subject in primary total knee arthroplasty. Asian patients often present late and consequently may have profound deformities due to significant bone loss and contractures on the concave side, and stretching of the collateral ligament on the convex side. Extra-articular deformities may aggravate the situation further and make correction of these deformities and restoration of ‘balance’ more arduous. These considerations do not apply if a hinged prosthesis is used, as may be warranted in an elderly, low-demand patient. However, in active, younger patients, it may be best to avoid use of excess constraint by balancing the soft-tissues and using the least constrained implant. Releasing collateral ligaments during TKA has unintended consequences such as the creation of significant mediolateral instability and a flexion gap which exceeds the extension gap; both of these may require a constrained prosthesis to achieve stability. We will show that soft-tissue balance can be achieved even in cases of severe varus, valgus, flexion and hyperextension deformities without collateral ligament release. The steps are: 1) Determining pre-operatively whether deformity is predominantly intra-articular or extra-articular, 2) Individualizing the valgus resection angle and bony resection depth, 3) Meticulous removal of osteophytes, 4) Reduction osteotomy, posteromedial capsule resection, sliding medial or lateral condylar osteotomy, extra-articular corrective osteotomy, 5) Compensating for bone loss, 6)Only rarely deploying a more constrained device. Case examples will be presented to illustrate the entire spectrum of varus deformities

Aim. To prevent infections after orthopaedic surgery, intravenous antibiotics are administered perioperatively. Cefazolin is widely used as the prophylactic antibiotic of choice. Systemic antibiotic therapy may however be less effective in longstanding surgery where bone allografts are used. Bone chips have been shown to be an effective carrier for certain types of antibiotics and may provide the necessary local antibiotic levels for prophylaxis. To be efficient a prolonged release is required. In contrast to vancomycin with proven efficient prolonged release from Osteomycin, this has not been described for cefazolin. We developed a protocol to bind cefazolin to bone chips by means of a hydrogel composed of proteins naturally present in the human body. Method. Three types of bone chips were evaluated: fresh frozen, decellularized frozen and decellularized lyophilized. Bone chips were incubated with 20 mg/ml cefazolin or treated with liquid hydrogel containing either 1 mg/ml fibrin or 1 mg/ml collagen and 20 mg/ml cefazolin. The cefazolin hydrogel was distributed in the porous structure by short vacuum treatment. Bone chips with cefazolin but without hydrogel were either incubated for 20 min- 4h or also treated with vacuum. Cefazolin elution of bone chips was carried out in fetal bovine serum and analysed by Ultra Performance Liquid Chromatography – Diode Array Detection. Results. Soaking of bone chips without hydrogel resulted in a quick release of cefazolin, which was limited to 4 hours. When vacuum was applied elution of >1 µg/ml cefazolin was measured for up to 36 hours. Combination with collagen hydrogel resulted in a higher cefazolin concentration released at 24 hours (3.9 vs 0.3 µg/ml), but not in a prolonged release. However, combination of decellularized frozen bone chips with fibrin hydrogel resulted in an initial release of 533 µg/ml followed by a gradual decline reaching the minimal inhibitory concentration for S. aureus at 72 hours (1.7 µg/ml), while not measurable anymore after 92 hours. Conclusions. Processed bone chips with hydrogel-cefazolin showed a markedly prolonged cefazolin release. When combined with a fibrin hydrogel, high initial peak levels of cefazolin were obtained, followed by a decreasing release over the following three days. This elution profile seems desirable, with high initial levels to maximize anti-bacterial action and low levels for a limited time to stimulate osteogenesis. Further preclinical studies are warranted to show effectiveness of hydrogel-cefazolin impregnated bone chips

Introduction. Dual modular hip prostheses were introduced to optimize the individual and intra-surgical adaptation of the implant design to the native anatomics und biomechanics of the hip. The downside of a modular implant design with an additional modular interface is the potential susceptibility to fretting, crevice corrosion and wear [1–2]. The purpose of this study was to characterize the metal ion release of a modular hip implant system with different modular junctions and material combinations in consideration of the corrosive physiological environment. Methods. One design of a dual modular hip prosthesis (Ti6Al4V, Metha®, Aesculap AG, Germany) with a high offset neck adapter (CoCrMo, CCD-angle of 130°, neutral antetorsion) and a monobloc prosthesis (stem size 4) of the same implant type were used to characterize the metal ion release of modular and non-modular hip implants. Stems were embedded in PMMA with 10° adduction and 9° flexion according to ISO 7206-6 and assembled with ceramic (Biolox® delta) or CoCrMo femoral heads (XL-offset) by three light impacts with a hammer. All implant options were tested in four different test fluids: Ringer's solution, bovine calf serum and iron chloride solution (FeCl3-concentration: 10 g/L and 114 g/L). Cyclic axial sinusoidal compressive load (Fmax = 3800 N, peak load level of walking based on in vivo force measurements [3]) was applied for 10 million cycles using a servohydraulic testing machine (MTS MiniBionix 370). The test frequency was continuously varied between 15 Hz (9900 cycles) followed by 1 Hz (100 cycles). The metal ion concentration (cobalt, chromium and titanium) of the test fluids were analysed using ICP-OES and ICP-MS at intervals of 0, 5·105, 2·106 and 10·106 cycles (measuring sensitivity < 1 µg/L). Results. Due to the additional modular interface between stem and neck adapter the total metal ion release of the modular hip endoprosthesis system increased significantly and is comparable to the coupling of a monobloc stem and a CoCrMo femoral head (Fig. 1). The application of ceramic femoral heads reduced the total cobalt and chromium release in the stem-head taper interface of non-modular and modular stems. In comparison between the four test fluids could be observed that lower pH-values and higher FeCl3-concentrations increased the metal ion release (Fig 2). In contrast, the use of bovine calf serum decreased the metal ion release of modular junctions due to the presence of proteins and other organic components. Discussion. For testing hip implants with proximal femoral modularity according to ISO and ASTM standards, sodium chloride solutions are frequently used to determine the fatigue strength and durability of the stem-neck connection. The present study illustrate that the expansion of standard requirements of biomechanical testing and the use of alternative test fluids is necessary to simulate metal ion release by electro-chemical processes. A promising approach is the use of adapted iron-chloride solutions (10 g/L FeCl3, pH 2) to evaluate the susceptibility of modular hip junctions to fretting, crevice and contact corrosion

Introduction. Well-balanced soft tissue is essential for achieving a good result when performing total knee arthroplasty. The preoperative planning is critical for ensuring a good operation. This study evaluated the preoperative distractive stress radiographs in order to quantify and predict the extent of medial release according to the degree of varus deformity in primary total knee arthroplasty. Methods. We evaluated 120 varus, osteoarthritic knee joints (75 patients). The association of the angle on the distractive stress radiograph with extent of medial release was analyzed. The extent of medial release was classified into the following 4 groups according to the stage: release of the deep medial collateral ligament (group 1), release of the posterior oblique ligament and/or semimembranous tendon (group 2), release of the posterior capsule (group 3) and release of the superficial medial collateral ligament (group 4). Results. Of the 120 cases for which medial release was performed, 30 (25.0%), 41 (34.2%), 20 (16.7%), and 29 (24.2%) cases were in group 1, 2, 3, and 4, respectively. After medial release, the difference between the medial and lateral gaps in flexion and extension was 0.1 mm (range, 0 to 1 mm) and 0.1 mm (range, 0 to 1 mm), respectively. The difference between the flexion and extension gaps was 0.6 mm (range, 0 to 1.5 mm). The mean femorotibial angle on the preoperative distractive stress radiograph was valgus 2.4° (group 1), valgus 0.8° (group 2), varus 2.1° (group 3) and varus 2.7° (group 4). The extent of medial release increased with increasing degree of varus deformity seen on the preoperative distractive stress radiograph.(Figure 1). Conclusions. The preoperative distractive stress radiograph was useful for predicting the extent of medial release when performing primary total knee arthroplaty. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Purpose. Surgeons sometimes encounter moderate or severe varus deformed osteoarthritic cases in which medial substantial release including semimembranosus is compelled to appropriately balance soft tissues in total knee arthroplasty (TKA). However, medial stability after TKA is important for acquisition of proper knee kinematics to lead to medial pivot motion during knee flexion. The purpose of the present study is to prove the hypothesis that step by step medial release, especially semimembranosus release, reduces medial stability in cruciate-retaining (CR) total knee arthroplasty (TKA). Methods. Twenty CR TKAs were performed in patients with moderate varus-type osteoarthritis (10° < varus deformity <20°) using the tibia first technique guided by a navigation system (Orthopilot). During the process of medial release, knee kinematics including tibial internal rotation and anterior translation during knee flexion were assessed using the navigation system at 3 points; (1) after anterior cruciate ligament resection (pre-release), (2) medial tibial and femoral osteophyte removal and release of minimum deep layer of medial collateral ligament (minimum release) and (3) release of semimembranosus (semimembranosus release). In addition, the kinematics after all prostheses implantation (semimembranosus release group) were assessed and compared with those assessed in another 20 patients in which only minimum release was performed (minimum release group). Results. Kinematic pattern in step by step medial release exhibited external tibial rotation during mid-range of flexion and then shifted to internal tibial rotation toward to 120 degrees of knee flexion (Fig. A). During 60 to 120 degrees of flexion, semimembranosus release significantly reduced the amount of internal tibial rotation compared with pre-release (Fig. 1B). Tibial anterior translation showed no significant differences among each procedure. After all prostheses implanted, the amount of tibial internal rotation during 60 to 120 degrees of knee flexion was significantly maintained in minimum release compared with semimembranosus release group (Fig. 2). Conclusions. Semimembranosus release reduces tibial internal rotation in CR TKA, suggesting that semimembranosus release should be avoided in case of moderate varus-type osteoarthritis for considering medial stability

Aim. Chronic osteomyelitis often requires surgical debridement and local antibiotic treatment. Disadvantages of PMMA carriers include low dose release and the requirement of surgical removal in the case of PMMA-beads. Synthetic nanocrystalline calcium phosphate (nCP) materials, which mimic the chemical structure of the mineral composition of bone, have been well accepted as bone grafting materials due to their consistent osteoconductivity, ease of use, and mechanical properties. Such a material which remodels into native bone is a much more attractive option. The aim of this study is to investigate the release of gentamicin from CaP in vitro and in vivo when implanted in a rabbit femoral condyle defect. Method. Three formulations of nCP were evaluated in this study: putty, paste and porous. Four cylindrical dowels were made for each group with gentamicin sulphate at a concentration of 20mg/cc of paste. Material was eluted in PBS at 37C and pH 7.0 and elutions were tested every day up to 30 days. Eighteen New Zealand white rabbits will undergo surgeries. Briefly, a drill defect will be created in the metaphyseal bone of the lateral femoral condyle. The formulations will be implanted in the created defect at time of surgery and the wound will be closed. Blood will be collected regularly and analysed for gentamicin titers. Animals will be sacrificed at 6wk, 12wk or 24wk. Explanted femurs will be fixed, sectioned and stained. Results. At 7 days the in vitro elution, showed a continued release of gentamicin. A large amount of gentamicin is released within the first day followed by a slow controlled release. The nCP putty shows the slowest release, followed by the paste and porous formulations respectively. There is a significant increase in the elution with an increase in porosity of the material. We expect to observe a similar trend in the rabbit study with an improved healing. At 6wk we expect the implant material to be still present at the site of implantation, which would remodel by 12wk and 24wk to significant levels due to active ossification. Conclusions. nCP materials, which undergo remodelling, can be used an effective carrier for gentamicin or other antibiotic agents. Because of its potentially prolonged release of high levels of antimicrobial agents, this system could maintain long-term antibacterial effectiveness locally

Introduction. The convincible wisdom is that the release of MCL in severe varus knee should be progressive. This release is usually carried on after resecting the osteophyte and gradually carried on until the MCL is well balanced. However, sometimes, extensive release and releasing the superficial MCL can lead to instability in flexion. On a personal communication with many Asian surgeons they have been doing a careful release of the posteromedial corner in the varus knee and in majority of cases such release is adequate. And even in severe cases of varus knee superficial MCL doesn't need to be released. 20 total knee replacements were performed by the same surgeon using ZimmerPS implant. In the varus deformity ranges from 15–35 degrees. The first bony section was made carefully. All osteophytes were removed and resected. The posterior bone osteophytes were also resected and the intercondylar notches were made along with the posterior release. After doing the bony cut in 18 of those cases the medial compartment was still tight and both flexion and extension. A careful release was carried in the postal medial corner-First using an osteotome around the posteromedial corner to release the soft tissue. After that the thick fibrous tissue that formed like pseudo meniscus was also resected until we were able to reach the posterior capsule. In some cases those scar tissues even extended to the capsule requiring the resecting of the postal medial capsule. We meticulously resected all those scar tissues and in many of those cases were able to visualize the MCL ligament which was well preserved. A tensioning device was used before and after the release. In all of those cases we were able to document an opening ranging from two to seven millimeter after the proper release. In all cases the superficial MCL were still intact and can be operated carefully. Result. This study clearly shows that we did not have to release the superficial MCL and the careful posteromedial release was adequate to obtain a good balance gap immediately and the knee was quite stable. The superficial MCL was maintained and preserved and tensioning device clearly document opening after releasing the postural medial corner. Discussion. In varus knee there is an extensive scar tissue which can sometimes tension the mcl ligament and releasing the deep mcl along with posture medial corner without releasing the superficial will preserve the stability of the knee allowing us to ambulate the patient immediately and preventing instability. Conclusion. Although MCL release has been described in diff ways in multiple literatures, little attention has been paid to the posture medial corner. This paper clearly shows that the complex anatomy of the posture medial corner along with scarring can lead to a tight mcl Releasing such structures would balance MCL&LCL without compromising the superficial MCL which normally lead to obvious flexion instability and a mid-section instability. We strongly recommend surgeon to do the posteromedial release before doing any release to the superficial mcl. Doing so will prevent the incidence of instability after extensive release in varus deformity

Antibiotic-loaded bone cements are used to decrease occurrence of bone infections in cemented arthroplasties and actually being considered as a more cost-effective procedure when compared to cementless implants [1]. However, considering the challenge of treating device-associated infections there is a reduced number of formulations in the market. Response from the industry to medical need is still slow considering the rapid change in the infecting microbial profile and the emergence of multiresistant strains [2]. In this context, the aim of the work is to evaluate the role of lactose (L), as a porogen, on the antibiotic release from bone cement (BC). Levofloxacin (Lev) and minocycline (M) were the selected antibiotics to be individually loaded into BC due to their low cost and potential application in bone infections [3,4]. Two types of matrices were prepared: 1) Loaded with 2.5% of antibiotics (controls) and 2) Loaded with 10% lactose and 2.5% antibiotic. In vitro drug release and microbiological tests against representative strains causative of bone infections were assessed. Lactose significantly increased the release of both antibiotics. Complete minocycline release after one-week was observed (Fig.1A). Also, lactose increased 3.5-fold the levofloxacin released from BC (Fig.1B). Furthermore, microbiological studies showed that no interaction was observed between lactose and antibiotic as no decrease in drugs antimicrobial activity was observed (Table 1). Considering the results, L-BC matrix appears to be a valuable alternative to available formulations. Future work will include testing other antibiotics as well as mixtures of drugs. Fundação para a Ciência e Tecnologia (Portuguese government) for financial support: EXCL/CTM-NAN/0166/2012 and strategic project PEst-OE/SAU/UI4013/2011