Examining the“revisability”benefit of hip resurfacing arthroplasty

BACKGROUND Hip resurfacing arthroplasty(HRA)is an alternative to total hip arthroplasty(THA)that is typically reserved for young active patients because it preserves bone.However,the benefits of HRA only hold true if conversion THA after failed HRA provides acceptable outcomes.AIM To compare patient reported outcomes for conversion THA after HRA failure to primary THA.METHODS A retrospective review of 36 patients(37 hips)that underwent conversion THA for failed HRA between October 2006 and May 2019 by a single surgeon was performed.Patient reported outcomes[modified Harris Hip Score(mHHS),University of California Los Angeles(UCLA)activity score]were obtained via an email-based responder-anonymous survey.Outcomes were compared to normative data of a primary THA cohort with similar demographics.Subgroup analysis was performed comparing outcomes of conversion THA for adverse local tissue reaction(ALTR)vs all other causes for failure.RESULTS The study group had a lower mHHS than the control group(81.7±13.8 vs 90.2±11.6,P<0.01);however,both groups had similar UCLA activity levels(7.5±2.3 vs 7.2±1.6,P=0.51).Patients that underwent conversion for non-ATLR causes had similar mHHS(85.2±11.5 vs 90.2±11.6,P=0.11)and higher UCLA activity levels(8.5±1.8 vs 7.2±1.6,P<0.01)compared to the control group.Patients that underwent conversion for ATLR had worse mHHS(77.1±14.5 vs 90.2±11.6,P<0.01)and UCLA activity levels(6.1±2.3 vs 7.2±1.6,P=0.05)when compared to the control group.CONCLUSION Patient outcomes equivalent to primary THA can be achieved following HRA conversion to THA.However,inferior outcomes were demonstrated for ALTR-related HRA failure.Patient selection and perhaps further studies examining alternative HRA bearing surfaces should be considered.

Buechel Pappas Resurfacing Shoulder Replacement: Evolution and over 40 Years of Clinical Experience

Background: Early exploration of the semi constrained “Floating-Socket” total shoulder replacement (TSR) in 1974 led to a proliferation of various unconstrained designs that allowed resection or retention of the humeral head, depending upon the pathological process involved. Degenerative glenohumeral arthritis with mild to moderate involvement of subchondral bone allowed for a resurfacing option, while severe humeral head involvement required a partial or full humeral head replacement attached to an intramedullary stem for fixation. All components evolved from cemented to cementless application by 1982. The purpose of this paper is to describe the progression of Buechel-Pappas (B-P) shoulder replacement development from the early 1970’s in both cemented and cement less applications. Methods: Clinical evaluations of “Floating-Socket” TSR, followed by B-P stem-type, resurfacing types, bipolar-type and revision components, all of which comprise the B-P Shoulder Replacement System, were performed over a 49-year period. Results: “Floating-Socket” implants improved the results of simple, constrained ball-in-socket designs, but generally failed by glenoid component loosening in both chimpanzee and human applications. Unconstrained resurfacing-type components, both anatomical humeral head and full proximal humeral components, were quite successful, with minimal failures observed in long-term studies. Bipolar salvage implants, used for severe proximal deficiencies, revisions and massive rotator cuff arthropathy, were also very successful;providing overhead range of motion in many patients. Conclusions: Resurfacing hemiarthroplasty, in patients with intact or repairable rotator cuff mechanisms, gave the most satisfactory results and were the least technically complicated to perform, requiring minimal instrumentation. Resurfacing of full proximal humeral deficiencies, using femoral resurfacing components, gave similar clinical results to more complex semi-constrained devices, also with less technical difficulties and simple instrumentation.

Cementless Buechel-Pappas Resurfacing Total Hip Replacement: A 45-Year Personal Journey to Overcome Wear, Osteolysis, Loosening and Femoral Neck Fractures

Background: Resurfacing-type total hip replacement (THR) has been successfully developed over the past 50 years through collaborative efforts between engineers and surgeons. Much of the development was pursued by individuals or groups, each of which participated in adding further refinements to the implants, instruments and surgical procedures, thus minimizing the serious problems of wear, osteolysis, loosening and femoral neck fractures. The purpose of this study is to explore the development process to optimize the resurfacing total hip replacement into its current application. Methods: In the early 1980s, cementless resurfacing implants were developed using “thin shell” technology to minimize bony resection of the acetabulum and femoral head. Femoral components utilized short, non-porous coated, tapered straight stems to reduce shear stresses in the femoral neck to prevent fractures and stress shielding, while mechanically stabilizing and aligning the components. Acetabular components were anatomically designed to be recessed inside bony borders to avoid neck-cup impingement and loosening. Initially, ultrahigh molecular weight polyethylene (UHMWPE) was used as a bearing, but due to high levels of wear and osteolysis, it was replaced by wear-resistant highly crossed-linked polyethylene (HXLPE) in 2008. Results: Use of HXLPE as a bearing material in both Co-Cr-Mo and titanium nitride (TiN) ceramic-coated resurfacing implants has led to excellent patient outcomes for more than 10 years. In clinical studies, 87% of patients with bilateral total hip replacements prefer their resurfacing-type total hip over their stem-type total hip. The author’s own personal resurfacing total hips, now at 8 and 5 years, respectively, provide “normal” function and no radiographic osteolysis. Conclusions: After 45 years of active evaluation, including mechanical design considerations, prosthetic design development, clinical and radiographic analysis of results, as well as availability of components cleared by the FDA 510 K process, the author has stated a personal preference for the BP Resurfacing Hip System. His excellent mid-term results in both of his resurfaced hips are similar to the long-term results presented in published studies.

Finite Element Analysis of the Contact Mechanics of Ceramic-on-Ceramic Hip Resurfacing Prostheses

Ceramics are good alternative to metal as bearing couple materials because of their better wear resistance. A Finite Element(FE) study was performed to investigate the contact mechanics and stress distribution of Ceramic-on-Ceramic (COC) hip resurfacingprostheses. It was focused in particular on a parametric study to examine the effects of radial clearance, loading,alumina coating on the implants, bone quality, and fixation of cup-bone interface. It was found that a reduction in the radialclearance had the most significant effect on the predicted contact pressure distribution among all of the parameters considered inthis study. It was determined that there was a significant influence of non-metallic materials, such as the bone underneath thebearing components, on the predicted contact mechanics. Stress shielding within the bone tissue was found to be a major concernwhen regarding the use of ceramic as an alternative to metallic resurfacing prostheses. Therefore, using alumina implantswith a metal backing was found to be the best design for ceramic resurfacing prostheses in this study. The loading, bone quality,and acetabular cup fixation conditions were found to have only minor effects on the predicted contact pressure distribution alongthe bearing surfaces.

Longitudinal evaluation of time related femoral neck narrowing after metal-on-metal hip resurfacing

AIM: To track the short-term neck narrowing changes in Birmingham metal-on-metal hip resurfacing(MOMHR) patients. METHODS: Since 2001, the Center for Hip and Knee Replacement started a registry to prospectively collect data on hip and knee replacement patients. From June 2006 to October 2008, 139 MOMHR were performed at our center by two participate surgeons using Birmingham MOMHR prosthesis(Smith Nephew, United States). It is standard of care for patients to obtain low, anteriorposterior(LAP) pelvis radiographs immediately after MOMHR procedure and then at 3 mo, 1 year and 2 year follow up office visits. Inclusion criteria for the present study included patients who came back for follow up office visit at above mentioned time points and got LAP radiographs. Exclusion criteria include patients who missed more than two follow up time points and those with poor-quality X-rays. Two orthopaedic residency trained research fellows reviewed the X-rays independently at 4 time points, i.e., immediate after surgery, 3 mo, 1 year and 2 year. Neck-to-prosthesis ratio(NPR) was used as main outcome measure. Twenty cases were used as subjects to identify the reliability between two observers. An intraclass correlation coefficient at 0.8 was considered as satisfied. A paired t-test was used to evaluate the significant difference between different time points with P < 0.05 considered to be statistically significant.RESULTS: The mean NPRs were 0.852 ± 0.056, 0.839 ± 0.052, 0.835 ± 0.051, 0.83 ± 0.04 immediately, 3 mo, 1 year and 2 years post-operatively respectively. At 3 mo, NPR was significantly different from immediate postoperative X-ray(P < 0.001). There was no difference between 3 mo and 1 year(P = 0.14) and 2 years(P = 0.53). Femoral neck narrowing(FNN) exceeding 10% of the diameter of the neck was observed in only 4 patients(5.6%) at two years follow up. None of these patients developed a femoral neck fracture(FNF). CONCLUSION: Femoral neck narrowing after MOMHR occurred as early as 3 mo postoperatively, and stabilized thereafter. Excessive FNN was not common in patients within the first two years of surgery and was not correlated with risk of FNF.

Fractional Ablative Radio-Frequency Resurfacing in Asian and Caucasian Skin: A Novel Method for Deep Radiofrequency Fractional Skin Rejuvenation

This paper reports the clinical experience of a multi-center, multiple physician trial with a novel fractional radiofrequency ablative skin resurfacing and rejuvenation device (Fractora, Invasix, Israel) deployed on both Caucasian skin types I - III and Asian skin type IV. Histological study demonstrated deep ablation and collagen restructuring in the papillary and reticular dermis. The Fractora device combines the more “cone shaped” ablation seen with CO2 and Erbium lasers with a deep non-ablative heating pattern, seen with other bipolar RF fractional needle resurfacing devices. Ablation, coagulation zones and healing dynamics are analyzed for different energy settings. Two different treatment protocols are suggested: one for light skin and then one for darker skin with a higher risk of post-inflammatory hypperpigmentation. Treatment results show improvement in skin texture, pores, wrinkles and skin dyschromia.

Effective Treatment of Atrophic and Icepick Acne Scars Using Deep Non-Ablative Radiofrequency and Multisource Fractional RF Skin Resurfacing

Background and Objectives: Effective treatment for atrophic (depressed) and icepick acne scars requires treatment of both epidermis—for roughness, texture and hyperpigmentation, and the dermis—for collagen remodeling. All first generation radiofrequency systems allow nonablative RF treatment while a few others allow simple bipolar Fractional RF skin resurfacing. The FDA cleared multisource radiofrequency therapy system (EndyMed PRO, EndyMed Ltd., Cesarea, Israel) allows, for the first time, phase controlled multisource RF for both deep (up to 11 mm) non ablative RF and fractional RF skin resurfacing on the same treatment device. Study Design/Materials and Methods: Ten subjects with atrophic acne scars were enrolled in the study. Patients were photographed using standardized methods. In each treatment session, each patient received a full face 3DEEP non ablative skin tightening treatment followed by a Fractional skin resurfacing treatment. The treatment sessions were repeated once a month to a total of up to 4 treatments. Results: All subjects experienced mild-moderate edema and erythema as an immediate response to treatment. Edema resolved after up to three hours post treatment and erythema lasted up to 2 days. Micro ablative crusts were formed 1 - 2 days post treatments and lasted up to 5 days on facial areas. Patients' photographs—before each treatment session and 1 and 3 months after the last session—were graded according to the accepted Cosmetic Improvement Scale. All patients obtained significant skin improvement. Seventy percent of patients had 50% - 75% improvement one month after the third treatment session while the other thirty percent experienced a 25% - 50%. Discussion and Conclusions: The presented results describe for the first time a new treatment system (EndyMed PROTM) that allows both deep non ablative RF delivery and Fractional skin resurfacing on the same treatment platform. This work shows the synergy of combining these two applications for the improvement of acne scars, as well as for some secondary possible pigmentation and vascular improvement.

Hip resurfacing arthroplasty complicated by mismatched implant components

Metal-on-metal hip resurfacing has gained popularity as a feasible treatment option for young and active patients with hip osteoarthritis and high functional expectations.This procedure should only be performed by surgeons who have trained specifically in this technique.Preoperative planning is essential for hip resurfacing in order to execute a successful operation and preview any technical problems.The authors present a case of a man who underwent a resurfacing arthroplasty for osteoarthritis of the left hip that was complicated by mismatched implant components that were revised three days afterwards for severe pain and leg length discrepancy.Such mistakes,although rare,can be prevented by educating operating room staff in the size and colour code tables provided by the companies on their prostheses or implant boxes.

Outcome and revision rate of uncemented humeral head resurfacing:Mid-term follow-up study

BACKGROUND Glenohumeral osteoarthritis(OA)is a common cause of pain and disability affecting nearly a third of the world’s population over 60 years of age.As in other joints,shoulder arthroplasty appears to be the most effective treatment.The implant design has evolved during time transitioning to shorter humeral stem lengths or even stemless components.AIM To evaluate the medium-term outcome and survival of a cementless humeral head resurfacing(HHR)in a group of patients affected with OA or avascular necrosis.METHODS This is a retrospective study of prospectively collected data using HHR in 23 patients(15 female and 8 male)after a 7.4 year follow-up.The collected data included clinical and radiographical evaluation.The Constant score,the visual analogue scale,and a clinical evaluation of range of motion were registered preand postoperatively.Fifteen patients affected with OA(2 cases of mild,6 moderate,and 7 severe)and 10 with avascular necrosis(stage III according to Cruess classification)were enrolled.X-rays were evaluated to detect loosening signs,degenerative changes,and superior humeral head migration.Magnetic resonance preoperatively was also performed to assess the rotator cuff status.Tendon integrity was mandatory to implant the HHR.RESULTS In total,19 patients(21 shoulders)completed the follow-up.Data on 4 shoulders,in 4 patients,were lost because of prosthesis failure.The global revision rate was 16%.A statistically significant improvement in the mean Constant score,visual analogue scale,and range of motion have been reported.No signs of loosening were registered,while in 12 cases a glenoid erosion was found.The osteophytes appeared 7 times on the humeral side and 12 on the glenoid.Superior humeral migration was recorded in only 1 case.CONCLUSION HHR remains a reasonable option in patients with an intact rotator cuff for the treatment of OA and avascular necrosis.

Periorbital Post-Inflammatory Hyperpigmentation after Fractionated CO₂Laser Resurfacing in Asians

Background: Most data on laser resurfacing have come from studies of people with Fitzpatrick skin types 1 - 3;however, the world’s population is comprised mostly of Fitzpatrick skin types 4 - 6, which are more susceptible to post-inflammatory hyperpigmentation (PIH). Objective: For the purpose of expanding the expertise of plastic surgeons treating patients with darker skin types, this study examined the incidence of PIH in Asians who underwent laser resurfacing, including a histologic arm on fractional ablative resurfacing. Methods & Materials: The clinical study included six subjects of Vietnamese origin who underwent single-depth fractionated CO2 laser resurfacing. The histologic study involved a seventh subject. The MiXto SX&reg;laser with a new scanning handpiece was used, along with magnifying loupes to assess ablative depth after each of three laser passes performed. Photographs were taken at various postoperative intervals. Results: All six clinical subjects showed cosmetic improvement in skin texture and tone with no post-inflammatory hyperpigmentation. In the histologic study, H&E stained sections revealed uniform diathermy. Conclusion: It is possible to significantly reduce PIH in darker skinned subjects through use of a new scanning handpiece and a technique using loupes to assess the depth of ablative resurfacing. The histologic study confirms these findings.

Transmastoid Approach for Resurfacing the Superior Semicircular Canal Dehiscence with a Dumpling Structure

Background： Superior semicircular canal dehiscence （SSCD） is gradually recognized by otologists in recent years. The patients with SSCD have a syndrome comprising a series of vestibular symptoms and hearing function disorders which can be cured by the operation. In this study, we evaluated the characteristics of patients with SSCD and determined the effectiveness of treating this syndrome by resurfacing the canal via the transmastoid approach using a dumpling structure. Methods： Patients with SSCD, confirmed by high-resolution computed tomography and hospitalized at Beijing Tongren Hospital between November 2009 and October 2012, were included in the study. All of the patients underwent the unilateral transmastoid approach for resurfacing the canal, and received regular follow-up after surgery. Data from preoperative medical records and postoperative follow-up were comparatively analyzed to evaluate the effect of surgery. Results： In total, 10 patients and 13 ears （three left ears, four right ears, three bilateral ears） were evaluated in the study, which included 7 men and 3 women. Different symptoms and distinctive manifestations of vestibular evoked myogenic potential were found in these patients. Alter surgery, 4 patients had complete resolution, 5 had partial resolution, and 1 patient, with bilateral SSCD, had aggravation. None of the patients suffered from serious complications such as sensorineural hearing loss, facial paralysis, cerebrospinal fluid leakage, or intracranial hypertension. Conclusions： In patients with unilateral SSCD, resurfacing the canal via the transmastoid approach using a dumpling structure is an effective and sate technique. However, more consideration is needed for patients with bilateral SSCD.

Long term follow up of clinical outcome between patellar resurfacing and nonresurfacing in total knee arthroplasty： Chinese experience

Background The long term outcome of patellar resurfacing in Chinese has not been well described.This study evaluated more than 10-year clinical outcomes and survivorship of patellar resurfacing or nonresurfacing in total knee arthroplasty.Methods From January 1993 to December 2002,265 patients accepted total knee arthroplasty in Department of Orthopaedic Surgery,Peking Union Medical College Hospital.Among them,226 patients （246 knees） were successfully followed up,with 176 knees for patellar resurfacing and 70 knees for nonresurfacing.The survivorship of total knee arthroplasty between two groups and the hospital for special surgery knee score （HSS）,patellar score,patellar related complication and radiological results were studied at the latest follow-up.Results The HSS knee score increased from 55.9±12.2 preoperatively to 92.0±10.9 postoperatively for patellar resurfacing group and from 56.6±9.9 to 94.2±11.4 for nonresurfacing group after average 11.4-year follow-up.Patellar score increased from 13.93±2.42 preoperatively to 28.33±2.20 for resurfacing group and from 13.55±2.73 to 27.8±2.37 for nonresurfacing group.There was no statistically significant difference for both HSS score,patellar score between the two groups with higher rate of anterior knee pain for nonresurfacing group.Patellar nonresurfacing had higher lateral subluxation than resurfacing group according to radiological evaluation.Patients with rheumatoid arthritis had 5.5 fold patellar related complication than patients with osteoarthritis.The 10-year survival rate was not statistically significant different between the two groups （P=0.12）.Conclusions There was no significant difference of long-term clinical outcome and survivorship between patellar resurfacing and nonresurfacing.Patellar nonresurfacing can be advisable during primary total knee arthroplasty especially in Chinese patients with osteoarthritis.Selective patellar resurfacing for patients with rheumatoid arthritis can achieve lower patella related complication.

Metallic resurfacing hemiarthroplasty of the first metatarsophalangeal joint combined with first metatarsal osteotomy for the treatment of hallux rigidus with hallux valgus in China

Hallux rigidus occurs mainly at the first metatarsophalangeal （MTP） joint,causing localized pain and degenerative arthritis.1 This condition frequently occurs together with hallux valgus and is difficult to treat.For hallux rigidus affecting only one joint,the treatment choices include articular debridement,resection arthroplasty,prosthetic arthroplasty,and arthrodesis,depending on the degree of arthritis.

Gait Analysis in Primary Total Knee Arthroplasty with and without Patellar Resurfacing:A Randomized Control Study

It is still controversial whether or not to resurface patella during primary total knee arthroplasty (TKA).One of the reasons may be insensitive measurement tools.We conducted a randomized controlled study to compare kinematic and kinetic parameters of resurfacing and nonresurfacing patella with the Vicon gait analysis system.The results show that patient post-operative gait of the two groups improved compared to pre-operative gait.Part of gait parameters,knee flexion at heel-strike,double limb support time and maximum adduction angle appeared to be statistically difference in 3 months,but 12 months later,the gait parameters of the two groups had no significant difference.Therefore,it seems that the final function of knee after TKA is not related whether or not to resurface patella.

超脉冲CO_2激光治疗眼睑缘痣细胞痣的疗效观察

目的:探讨超脉冲CO2激光治疗眼睑缘痣细胞痣的疗效与安全性。方法:使用超脉冲CO2激光治疗仪在眼罩保护,局部注射麻醉下,采用能量18～35mJ/cm2,频率20～30Hz治疗眼睑缘痣细胞痣42例。结果:随访3个月后其中39例皮损完全消退,无复发,3例皮损明显缩小,残留芝麻大小黑点,再次治疗后皮损消失。总有效率100%,患者满意,无不良反应及副作用。结论:采用超脉冲CO2激光治疗眼睑缘痣细胞痣操作简单、安全,效果显著,无副作用。

Common controversies in total knee replacement surgery: Current evidence

Total knee replacement(TKR) is a widely used operation that has radically improved the quality of life of millions of people during the last few decades. However, some technical details, concerning the surgical procedure and the rehabilitation following total knee arthroplasty, are still a matter of a strong debate. In this review of the literature, we have included the best evidence available of the last decade, in an effort to shed light on some of the most controversial subjects related to TKR surgery. Posterior-stabilized or cruciate-retaining prosthesis? To use a tourniquet during operation or not? Do patients need continuous passive motion for their post-surgery rehabilitation? To resurface patella or not? These are some of the most controversial topics that until now have been persistent dilemmas for the orthopedic surgeon. Results of this systematic review of the literature are highly controversial. These conflicting results are an indication that larger and more well conducted high quality trials are needed in order to gain more secure answers. At the same time, it is becoming apparent that a meticulous operative technique, respecting the soft tissue envelope and knowing the principles of alignment and soft tissue balancing, aresome of the parameters that might contribute more to achieving the optimal results for the patients.

Adverse Wear in MOM Hip-Arthroplasty Related to the Production of Metal Fragments at Impingement Sites

Metal on metal (MOM) bearings were reintroduced as resurfacing arthroplasty (RA) for the younger, more active patient and were later incorporated into total hip arthroplasty (THA). Early results were encouraging. However, recent publications identified adverse tissue responses to metal debris, such that the majority of MOM designs have been abandoned due to the increase in cobalt-chromium (CoCr) debris and associated metal ions. Reports of MOM THA cited risks that included acetabular cups with high-inclination angles, i.e. “edge-loading”, and “trunnionosis”. Hip impingement was also a cited risk in one MOM study, with “type-IV” wear noted to be a sliding/impaction type of wear, characterized by deep scratches. Sliding/impaction wear mechanisms produced at impingement are not well represented in current MOM literature. Therefore, our objective in this review was to consolidate evidence for impingement risks. We hypothesize that hip impingement and subluxation with metal-backed acetabular cups can trigger wear mechanisms that result in, 1) femoral-neck notching, 2) release of large metal particles, 3) production of uniquely large scratches, defined as “microgrooves” on heads and cups, 4) formation of “polar” and “basal” microgrooves precisely aligning with cup profiles during impingement, and 5) equatorial microgrooves relate to soft-tissue sites of impingement. Relevant risk scenarios were evaluated and included hip impingement in both sitting and standing postures, head subluxation, wear patterns defining in-vivo component positions, and evidence for circulating metal fragments. The study relied on mapping of wear patterns to deduce in-vivo positioning of devices and relied on surrogate femoral stems of the same brand to simulate neck-cup impingement. EOS imaging techniques were used to analyze functional-sitting and functional-standing postures and prove existence of hip impingement sites in patients. The study identified 8-risk scenarios for wear damage on MOM bearings. The microgrooves on femoral-heads crossing the main-wear area (polar) and non-wear regions (basal) aligned well with cuprim profiles at impingement sites. This may represent the first description of such large scratches (40 - 300 μm wide) we termed microgrooves, that formed on femoral heads at sites representative of prosthetic impingement. As an abrasive wear process, similar to the formation of femoral-neck notches, these would have been acquired over millions of gait cycles. The pitting and linear microgrooves crossing the non-wear areas of heads (basal) represented the ingress sites of circulating metal particles. Similar micro-grooves were evident in acetabular cups, also signifying 3rd-body abrasion by large metal particles. Hip impingement and head subluxation were implicated by the unequivocal evidence of 3rd-body abrasive wear as the triggering events producing large metal fragments. One caveat regarding retrieval studies is that such damage may be only representative of failed MOM devices. This study demonstrated that emerging technologies such as EOSTM x-ray analyses can reveal subtle changes in implant positioning using patient shifts in functional postures (sitting, standing, hyper-extension, etc.), and thereby assess impingement/subluxation risks in the clinical setting before failure occurs.

Advances in penile-sparing surgical approaches

Objective:Penile cancer(PeCa)is a rare disease with a global incidence of 36068 new cases in 2020.This accounts for 0.4%of all male malignancies.The surgical management of PeCa depends on the location of the tumour and depth of invasion.Here,we review the oncological and functional outcomes of penile-preserving surgery(PPS).Methods:A PubMed search until July 2021 on PPS for PeCa was conducted;a narrative review on different penile-sparing approaches and outcomes was performed.Results:PPS is now the standard of care in specialist centres for distal tumours not involving the corpus cavernosa.Laser therapy,glans resurfacing,and wide local excision are options for superficial lesions,whilst glansectomy is required for lesions invading into the corpus spongiosum.Conclusion:PPS aims to preserve urinary and sexual function without compromising oncological outcomes.

Effects of Hip Arthroplasties on Bone Adaptation in Lower Limbs: A Computational Study

Gait disorders contribute to the risk of falls and successive injuries, especially to elderly populations. The risk of falls becomes higher for hip osteoarthritis (OA) and hip arthroplasties patients due to poor balancing and gait impairment. Bone adaptation and bone loss are fundamental issues in considering the changes of bone behavior and gait pattern. In this study, computational analysis of the lower limbs was conducted to estimate the bone adaptation after hip arthroplasties procedure. 3D inhomogeneous model of lower limb was developed from computed topography (CT- based) data of 79 years old patient with hip osteoarthritis problem in left limb. Two types of arthroplaties were constructed in the left limb, namely total hip arthroplasty and resurfacing hip arthroplasty using commercial biomedical software, Mechanical Finder v6.1. Prosthesis stem and acetabular cup of THA were modelled as titanium alloy material (E = 114 GPa, v = 0.34), femoral ball and bearing insert as alumina properties (E = 370 GPa, v = 0.22). Meanwhile, RHA implant was assigned as Co-Cr-Mo material (E = 230 GPa, v = 0.30). Contact between both implants and bone were considered to be perfectly bonded at the interface. A load case of quiet standing position was conducted in this analysis with 60 kg of the patients’ body weight. The load was applied at the cross sectional lumbar vertebra and fixed at the distal of femoral shafts. Results show different patterns of stress distribution in right and left (operated) limbs for hip OA, THA and RHA models. An indication of stress alteration on both limbs after arthroplasties suggested that the bone adaptation occurred. The higher percentage of change in the left limb projected that the adaptation was more critical in operated limb.