The Association of Acetabulum Fracture and Mechanism of Injury with BMI, Days Spent in Hospital, Blood Loss, and Surgery Time: A Retrospective Analysis of 67 Patients.

Background and Objectives: The objective of this retrospective study was to investigate the association between acetabulum fractures; the mechanism of injury; and variables such as BMI, duration of hospital stay, blood loss, and surgery time. By exploring these factors, we aim to enhance our understanding of them and their impact on the healing process and the subsequent management of pelvic fractures. Materials and Methods: This study included 67 of 136 consecutive patients who were admitted for pelvic ring fracture surgery between 2017 and 2022. The data were collected prospectively at a single trauma center. The inclusion criteria were acetabulum fractures and indications for operative treatment. The exclusion criteria were non-operative treatment for acetabular and pelvic ring fractures, fractures requiring primary total hip arthroplasty (THA), and periprosthetic acetabular fractures. Upon admission, all patients underwent evaluation using X-ray and computed tomography (CT) scans of the pelvis. Results: The present study found no statistically significant differences between the examined groups of patients with pelvic fractures in terms of BMI, surgery duration, length of hospital stay, and blood transfusion. However, two notable findings approached statistical significance. Firstly, patients who experienced a fall from height while sustaining a pelvic fracture required a higher number of blood transfusions (2.3 units) than those with other mechanisms of injury which was close to achieving statistical significance (p = 0.07). Secondly, patients undergoing posterior wall stabilization required a significantly lower number of blood transfusions than those with other specific pelvic injuries (0.33 units per patient), approaching statistical significance (p = 0.056). Conclusions: The findings indicated that factors such as BMI, time of surgery, blood loss, and the duration of hospital stay were not directly correlated with the morphology of acetabular fractures, the presence of additional trauma, or the mechanism of injury. However, in the studied group, the patients whose mechanism of trauma involved falling from height had an increased number of blood transfusions compared to other groups. Moreover, the patients who had surgery due to posterior wall acetabulum fracture had decreased blood transfusions compared to those with other Judet and Letournel types of fractures. Additionally, they had the shortest duration of surgery.

Effect of screw angulation and multiple insertions on load-to-failure of polyaxial locking system.

PURPOSE: Polyaxial locking plates rely on the alignment between the thread-to-thread connections of the screw head and the plate hole. These implants have provided substantial support for surgeons. In particular, extended screw positioning have proven to be beneficial in the fixation of challenging fractures. This study aimed to investigate the mechanical properties of ChM 5.0 ChLP polyaxial screws inserted in off-axis trajectories, including multiple insertions and to correlate these parameters with the screw head and the plate hole thread-to-thread engagement. METHODS: Polyaxial locking screws were inserted into the plates at various angles (0°,10°,15°, -15° off-axis). Multiple time inserted screws were placed firstly at 15°, then 0° and finally -15° off-axis in the same plate hole. A microCT scan of the plate-hole and screw-head interface was conducted before destructive tests. Representative screws from each group were also examined by Scanning Electron Microscope. RESULTS: The standard insertion at 0° sustained the greatest maximum bending strength without relocation in the screw hole. Screws inserted at 10° and 15° (one time) showed a significant reduction in load-to-failure of up to 36% and 55%, (p = 0.001) (p = 0.001) respectively. Screws inserted at -15° after a maximum of three multiple insertions with angle shift, showed a total reduction in force of up to 70% (p = 0.001). A microCT analysis of thread engagement showed significant correlations. However, the results obtained for multiple insertions were highly variable. CONCLUSIONS: ChM 5.0 ChLP polyaxial locking system has valuable properties that foster fracture fixation, providing various surgical options. Nevertheless, the freedom of off-axis placement and multiple insertions of the screws comes at the price of reduced force. When possible surgeons should minimize the angles of insertions.

Effect of screw angulation on the bending performance of polyaxial locking interfaces: a micro-CT evaluation.

Polyaxial locking plates rely on a specific thread-to-thread interface of the screw head and the plate hole. The objective of this study was to evaluate the mechanical performance of single screw interfaces when inserted off-axis and to establish correlations between those parameters and the engagement of the screw head and the plate hole thread. Three polyaxial locking screw systems were inserted into the corresponding plates at various angles (0°, 5°, 10°, and 15° off-axis). The screws were tested until failure. A micro-CT was performed to examine the interface between the plate hole and the screw head. The standard insertion at 0° sustained the greatest maximum bending strength without relocation in the screw hole. Screws inserted at 15° showed a significant reduction in force of up to 44%, 55% and 57%, respectively. Micro-CT analysis of the interface showed a significant loss of thread engagement for off-axis insertion. Polyaxial plates offer additional advantages for off-axis placement of screws. However, this flexibility is related to a significant decrease in both thread engagement and bending strength compared to monoaxial insertion. Regardless the insertion angle, the loss of stability is comparable when screws are placed off-axis. Surgeons are advised to consider off-axis insertion as a salvage option, providing access to better bone stock.

Biomechanical evaluation of variable angle locking systems. A micro-CT analysis.

PURPOSE: Formerly poor bone stock and periprosthetic fractures used to jeopardize monaxial constructs. Polyaxial locking screws have substantially supported those particular fixation constructs. However, those systems rely on complex alignment between the screw head and the plate hole. This study aimed to investigate the mechanical properties of several polyaxial systems and to correlate these parameters with the screw head and the plate hole engagement. METHODS: Polyaxial locking systems were tested with screws inserted into the corresponding plates at various angles (0°, 5°, 10°, 15°). A micro-CT scan of the plate-hole and screw-head interface with the quantification of average thread engagement was performed before destructive tests. The screw-plate interface of each system was tested in a cantilever bending setup. Representative screws and plates were also examined by SEM. RESULTS: The standard insertion at 0° sustained the greatest maximum bending strength in all analyzed systems. Point-loading thread-in and cut-in screws inserted off-axis showed a significant reduction in bending strength (p<0.001) (p=0.041) (p<0.001). In contrast, locking cap screws maintained similar bending strength with disregard to the angle of insertion (p<0.4849). A micro-CT analysis confirmed that the average thread engagement of point-loading thread-in, cut-in and locking-cap screws was significantly reduced when placed off-axis (p=0.005) (p<0.001) (p=0.002) (p<0.001). The locking-cap mechanisms maintained the highest average thread engagement among all analyzed systems. CONCLUSIONS: The mechanical performance of polyaxial locking plates usually comes at the price of reduced bending strength. Surgeons should limit polyaxial insertions depending on the particular system's characteristics.

The Association between Acetabulum Fractures and Subsequent Coxarthrosis in a Cohort of 77 Patients-A Retrospective Analysis of Predictors for Secondary Hip Osteoarthritis.

OBJECTIVE: the aim of this study was to document the occurrence of THA after acetabulum surgery and examine the factors that predict its occurrence. METHODS: This study included 77 consecutive patients who were admitted for acetabulum fracture surgery between 2012 and 2019. The inclusion criteria were acetabular fractures and indications for operative management. The exclusion criteria were acetabular fractures treated non-operatively, fractures requiring primary THA, and periprosthetic acetabular fractures. Data concerning demographics, date of injury, date of surgery, surgical approach, stabilization, and further reconstructive surgery were collected retrospectively. The number of patients who underwent THA and their risk factors were recorded. The minimum follow-up for each patient was 2 years of observation. A total of 77 patients with a mean age of 53 years were included. RESULTS: At a mean follow-up of 2 years, THA was performed in 16 (20.8%) patients due to post-traumatic arthritis. An analysis of the surgical approaches showed that the Kocher-Langenbeck approach increased the risk of THA nearly 12 times compared with the ilioinguinal approach (p = 0.016). Furthermore, the duration of the waiting period for surgery significantly impacted the occurrence of THA, with each additional day leading to an 89% increase in the risk of prosthesis usage (p = 0.001). CONCLUSIONS: This study suggests that acetabular fractures may lead to post-traumatic hip osteoarthritis. The surgical approach and the waiting time for surgery are potential factors that may predict secondary hip osteoarthritis and the need for subsequent THA. However, further investigations should be performed to establish predictors for secondary hip osteoarthritis, and especially to determine the impact of the surgical approach.

Damage analysis of retrieved BioloxⓇdelta components used in hard and soft bearings.

This retrieval study included 43 Biolox delta explants (18 CoC, 25 CoP). Implants were examined macroscopically, whereby damage was evaluated using a semi quantitative scoring system. Confocal microscopy was used to examine wear related damage patterns of the articulating surfaces. Scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) was used to analyze wear marks on the implant surface and wear debris in periprosthetic tissue samples. Raman spectroscopy and X-ray diffraction (XRD) were used to quantify monoclinic zirconia fractions. On all components, in vivo wear resulted predominantly in different damage patterns caused by metal transfer. In CoC bearings stripe wear was additionally detected, and some implants underwent severe damage due to component breakage. The wear scores were higher for CoC components, with no differences between the scores for CoC heads and liners. Wear features caused comparable roughening on implants from CoC and CoP bearings. SEM studies demonstrated that most wear marks were caused by metal debris released from implant components. Grain pull-out was observed in stripe wear regions. Monoclinic phase shift was observed in a similar quantity on components from CoP and CoC bearings. The increase of monoclinic zirconia content around metal deposits was minimal and was more pronounced in areas of stripe wear. The results of this study indicate, that ZTA components in general undergo minimal wear in both, CoC and CoP bearings, however, it is more pronounced in the former. Metal deposits, as the most common wear feature, have no significant effect on monoclinic phase transition. STATEMENT OF SIGNIFICANCE: In this paper, we classify all damage patterns macroscopically according to an established scoring system and assess them regarding surface roughness (confocal microscopy) and monoclinic phase content (Raman spectroscopy) in order to derive the severity for patients. We compare hard-hard and hard-soft bearings and relate damage patterns with metal transfer based on SEM/EDS examinations. Furthermore, we work out correlations between patient-specific data, cause of revision and the physical condition of each individual sample Our cohort consists of 43 Biolox delta retrievals, a comparatively large quantity. In addition, we address current topics such as metal transfer and, based on the classification of damage patterns, provide incentives and/or meaningful focal points for further research.

Smoking Has No Influence on Outcomes after Repair of the Medial Meniscus in the Hypo and Avascular Zones-A Pilot Study.

Complete loss of the meniscus inevitably leads to knee joint degeneration. Smoking is an important factor predicting poor outcome in orthopedics; however, data about its role in meniscus surgery are inconclusive. Smoking could be an important negative factor in isolated meniscus repair. The aim of this paper was to determine the influence of smoking on functional outcomes after isolated all-inside medial meniscus repair. This study included 50 consecutive patients with isolated, traumatic tear of the medial meniscus who underwent knee joint arthroscopy between 2016 and 2019. All-inside arthroscopic repair of the medial meniscus was performed in each case. All patients followed a uniform, postoperative rehabilitation protocol for 8 weeks. The follow-up examination was based on the functional scores at 3 and 6 months postoperatively. According to smoking status there were 17 smokers and 33 non-smokers. The mean number of cigarettes smoked per day was 11, for a mean of 7.4 years, and the mean pack-years index value was 4.9. There was no correlation between smoking years, number of cigarettes smoked per day, pack-years index, and functional outcomes. The arthroscopic inspection of the knee joints revealed cartilage lesions (≤IIº) in eight subjects, suggesting the secondary pathology to the meniscus tear. In this study, we found no evidence of an association between smoking indices and functional outcomes after all-inside repair of chronic medial meniscus tear. The nature of the chronic meniscal tear could be smoking-resistant owing to the poor blood supply to the sites in which these specific lesions occur.

Resection of Infrapatellar Fat Pad during Total Knee Arthroplasty Has No Impact on Postoperative Function, Pain and Sonographic Appearance of Patellar Tendon.

Routine resection of the infrapatellar fat pad (IFP) during total knee arthroplasty (TKA) is controversial, as it may result in shortening of the patellar tendon (PT) and anterior knee pain. This prospective study examined whether IFP excision during TKA affects joint function, anterior knee pain, PT dimensions and sonographic structure. A total of 65 consecutive patients undergoing TKA for osteoarthritis were randomized into two groups: IFP was resected in one and retained in the other. Patients were examined preoperatively, at 6 weeks and 6 months postoperatively: pain (Numerical Rating Scale-NRS), range of motion (ROM) and knee function (Knee Injury and Osteoarthritis Outcome Score-KOOS score) were evaluated; sonographic examination determined the length, structure and vascularity of the PTs. In both groups there were postoperative improvements in NRS and KOOS scores, although IFP resection did not influence clinical outcomes or sonographic parameters. At 6 weeks and 6 months postoperatively for both groups there were no differences between NRS scores (Mann-Whitney test, p = 0.511 and p = 0.579), ROM scores (Mann-Whitney test, p = 0.331, p = 0.180) or all KOOS subscores. IFP excision had no effect on sonographic parameters. This study suggests that IFP resection during TKA does not influence postoperative functional outcomes, pain scores, patellar tendon length and thickness, or sonographic structure.

Mini-Invasive, Ultrasound Guided Repair of the Achilles Tendon Rupture-A Pilot Study.

Percutaneous acute Achilles tendon rupture suturing has become a leading treatment option in recent years. A common complication after this mini-invasive procedure is sural nerve injury, which can reduce the patients' satisfaction and final outcomes. High-resolution ultrasound is a reliable method for localizing the sural nerve, and it can be performed intra-operatively; however, the long-term results are yet unknown. The aim of the study was to retrospectively evaluate the long-term results of percutaneous Achilles tendon repair supported with real-time ultrasound imaging. We conducted 57 percutaneous sutures of acute Achilles tendon rupture between 2005 and 2015; 30 were sutured under sonographic guidance, while 27 were performed without sonographic assistance. The inclusion criteria were acute (less than 7 days) full tendon rupture, treatment with the percutaneous technique, age between 18 and 65 years, and a body mass index (BMI) below 35. The operative procedure was carried out by two surgeons, according to the surgical technique reported by Maffulli et al. In total, 35 patients were available for this retrospective assessment; 20 (16 men and 4 women) were treated with sonographic guidance, while 15 (12 men and 3 women) underwent the procedure without it. The mean follow-up was 8 years (range, 3-13 years). The sural nerve was localized 10 mm to 20 mm (mean, 15.8; SD, 3.02) laterally from the scar of the Achilles tendon tear. There was no significant difference between groups with respect to the FAOQ score (P < 0.05). High-resolution ultrasounds performed intra-operatively can minimize the risk of sural nerve injury during percutaneous Achilles tendon repair.

Relationship between long head of the biceps tendon histopathology and long-term functional results in smokers. A time to reevaluate the Bonar score?

AIM: The purpose of this study was to investigate whether there is an association between smoking, the extent of the degeneration process in the biceps tendinopathy, including cells and extracellular matrix (ECM) alterations, and long-term surgical results. METHODS: This study comprised 40 consecutive patients admitted for shoulder arthroscopy due to symptomatic biceps tendinopathy and classified into three groups based on smoking status: active smokers, former smokers, and non-smokers. According to the classical Bonar score criteria, the histopathologic evaluation of the harvested intra-articular portion of the tendon was done. The follow-up examination was based on the American Shoulder and Elbow Surgeons Score (ASES). RESULTS: A cohort of 32 patients was enrolled in the final follow-up examination; mean 37.56 months. Histopathological evaluation according to the classical Bonar score revealed degeneration of the tendinous tissue in each group but there was no correlation between the extent of degeneration, smoking indexes and the ASES. After revision of Bonar scale within the vascularity criterion, we found a correlation between the extent of degeneration of tendinous tissue, smoking data, ASES score, and the severity of rotator cuff injury. CONCLUSION: In this paper, we indicate the ambiguous role of the neovascularization in the biceps tendinopathy, and it was used for modification of the classical Bonar score. Consequently, recalculated, modified Bonar score was correlated positively with smoking indexes and functional outcomes. Furthermore, the morphological alterations of rotator cuff tendons also correlated positively with the extent of biceps tendon degeneration, measured according to the modified scoring system.

The Impact of Smoking on Clinical Results Following the Rotator Cuff and Biceps Tendon Complex Arthroscopic Surgery.

The purpose of this study was to investigate the association of smoking and functional outcomes after arthroscopic treatment of complex shoulder injuries: rotator cuff tears (RCTs) with biceps tendon (LHBT) tears. This retrospective case-control study has been conducted on a cohort of patients who underwent shoulder arthroscopy between 2015 and 2017 due to complex injury treatment. The outcomes were assessed using the American Shoulder and Elbow Surgeons Score (ASES), the University of California at Los Angeles (UCLA) Shoulder Score, need for non-steroid anti-inflammatory drugs (NSAIDs) consumption and the visual analog scale (VAS). Complications and changes in smoking status were also noted. A cohort of 59 patients underwent shoulder arthroscopy, due to complex LHBT pathology and RCTs, and were enrolled in the final follow-up examination; with mean duration of 26.03 months. According to smoking status, 27 of patients were classified as smokers, and the remaining 32 were non-smokers. In the examined cohort, 36 patients underwent the LHBT tenotomy and 23 tenodesis. We observed a relationship between smoking status and distribution of various RCTs (p < 0.0001). The mean postoperative ASES and UCLA scores were 80.81 and 30.18 in the smoker's group and 84.06 and 30.93 in the non-smoker's group, respectively. There were no statistically significant differences in pre/postoperative ASES and postoperative UCLA scores between smokers and non-smokers (p > 0.05). The VAS was significantly lower in the non-smokers' group (p = 0.0021). Multi-tendon injuries of the shoulder are a serious challenge for surgeons, and to obtain an excellent functional outcome, we need to limit the negative risk factors, including smoking. Furthermore, there is a significant association between smoking and the occurrence of massive rotator cuff tears, and the pain level measured by the VAS. Simultaneous surgical treatment of RC and LHBT lesions in the smoker population allowed us to obtain the functional outcomes approximated to non-smokers in the long-term follow-up. Of course, we cannot assert that smoking is the real cause of all complications, however, we may assume that this is a very important, negative factor in shoulder arthroscopy.

Biceps Tenodesis versus Tenotomy with Fast Rehabilitation Protocol-A Functional Perspective in Chronic Tendinopathy.

The study aimed to evaluate the results after arthroscopic tenodesis and tenotomy of the biceps tendon (LHBT), coupled in tenotomy modality with a personalized postoperative rehabilitation protocol. The study included patients who underwent arthroscopic biceps tenotomy or tenodesis due to chronic biceps tendinopathy. Postoperatively, a standard rehabilitation program was prescribed to the tenodesis group and personalized was introduced in the tenotomy group, respectively. The outcomes were assessed using the American Shoulder and Elbow Surgeons scale (ASES), clinical tests that are dedicated to biceps tendinopathy, the occurrence of a Popeye deformity, night pain, and return to previous sporting activities. A cohort of 67 patients was enrolled in the final follow-up examination (mean 27 months) of which 40 patients underwent tenotomy (60%), and 27 patients (40%) underwent tenodesis. The mean ASES score improved from 48.1 to 87.8 in the tenotomy group and from 44 to 72.7 in the tenodesis group during the follow-up (p < 0.0001). The tenotomy group had better mean postoperative ASES scores than the tenodesis group (p < 0.0001). Positive clinical tests for biceps pathology were noticed more often in patients after LHB tenodesis (p = 0.0541). The Popeye deformity occurred more often in the tenotomy group; however, no patient complained of the visual appearance of the arm contour (p = 0.0128). Moreover, the frequency of night pain decreased in the tenotomy group (p = 0.0059). Return to previous sporting activities was more frequent in the tenotomy group (p = 0.0090). Arthroscopic biceps tenotomy is a reproducible, simple procedure, and augmented by a rapid rehabilitation protocol that provides promising clinical outcomes, reduces shoulder pain, and allows the patient to return to previous sporting activities, even in population older than 50 years.

Retrieval analysis of TiN (titanium nitride) coated knee replacements: Coating wear and degradation in vivo.

INTRODUCTION: Titanium nitride (TiN) coatings are used in joint arthroplasty to minimize wear and reduce the allergenic potential of metal implants, yet little is known about their performance in knee arthroplasty. This retrieval study examined TiN coated knee replacements to verify in vivo wear and degradation of the coating. MATERIALS AND METHODS: This study included total and unicompartmental mobile bearing knee replacements retrieved from five patients (eight components) after 13-21 months due to aseptic loosening or infection. Implants were examined using scanning (SEM) and optical microscopy, surface damage was assessed using a semiquantitative scoring system, adhesion was determined using indentation technique testing, surface roughness was measured using contact profilometry. RESULTS: Although good coating adhesion and no gross failure were observed on all retrievals, coating wear and roughening were evident on tibial bearing surfaces. Multiple microscopic defects (pinholes, craters, titanium droplets) were observed on all samples in SEM studies. Microscopic wear scars indicated that particulate defects significantly contributed to coating wear, acting as third bodies. CONCLUSION: TiN coatings of knee replacements undergo wear and degradation related to presence of third bodies and microscopic defects on their surface. Since coating integrity may be compromised in vivo, such implants should be used with caution in metal sensitive patients.

Breakage of metal hip arthroplasty components: Retrieval and structural analysis.

BACKGROUND: Breakage of joint arthroplasty components are rare, yet during an implant retrieval program we found several cases. OBJECTIVE: In this study we examined the components to determine the causes and mechanisms of breakage of these implants. METHODS: From our collection of 849 retrievals we selected 682 cases with metal parts (503 hip, 79 knee arthroplasties) and identified fractured components: seven hip resurfacing implants, five total hip replacement stems, one monopolar femoral head, and one modular revision femoral stem from. Implants were examined using optical and scanning electron microscopy; metallographic sections were prepared and samples of periprosthetic tissues underwent microscopic examination. RESULTS: In the resurfacing components breakage occurred in small stems placed in the femoral neck due to necrosis of femoral heads, with no metal flaws detected. Fatigue breakage of femoral stems was caused by presence of material flaws in the CoCrMo alloy, and corrosion. The monopolar head failed in fatigue fracture mechanism, breakage was initiated in an undercut near the taper connection for femoral component. The modular stem from Ti alloy sustained fatigue fracture induced by corrosion caused by debris from previously revised stem; no material flaws were detected in this sample. In most cases periprosthetic tissues had a morphology typical for aseptic loosening. CONCLUSIONS: In our series failure was caused by material flaws, presence of stress raisers and localized corrosion. Our findings indicate that sharp edges and other features which can act as stress raisers should be avoided in newly designed implants. Corrosion induced fracture of the modular Ti stem indicates the need for a detailed debridement of periprosthetic tissues during revision arthroplasties.

Pigmented Villonodular Synovitis - Various Manifestations, Inconsistent Terminology and Treatment. Cases Study.

Pigmented villonodular synovitis (PVNS) as well as tenosynovial giant cell tumor (TGCT) are both diagnosed and described in two forms, namely a localized and diffuse type. They form a diverse group of proliferative lesions in articular synovium and tendon sheaths. The inconsistent terminology impedes communication between patients, orthopedic surgeons, radiologists and pathologists, leading to misunderstandings and delaying treatment. In this paper, we present three cases of PVNS/TGCT (involving the fourth toe extensor tendon sheath, hip joint after resurfacing and flexor hallucis longus tendon sheath) together with suggestions regarding the unification of the terminology as well as diagnosis and treatment.

Is the inflammation process absolutely absent in tendinopathy of the long head of the biceps tendon? Histopathologic study of the long head of the biceps tendon after arthroscopic treatment.

Tendinopathy of the long head of the biceps tendon is a difficult medical issue. Its pathogenesis and etiology is multifactorial and unclear. Tendinopathy is thought to be primarily degenerative in nature, as tendons are characterized by impaired regeneration and healing. Thirty-five patients with preoperatively diagnosed tendinopathy of long head of the biceps tendon were referred to the Orthopedics Department. All patients underwent an arthroscopic-assisted biceps tenodesis or tenotomy. The intra-articular portion of the long head of the biceps tendon was obtained from each of the patients who underwent arthroscopy. A macroscopic and microscopic evaluation of biceps tendon samples revealed degeneration among all specimens. This study demonstrates the prevalence of the degeneration process and the presence of marginal inflammation process in tendinopathy of the long head of biceps tendon. The role, that inflammation process plays in tendinopathy is important in the early phase and gradually becomes secondary to the developing degeneration. The inflammatory cells, occasionally seen in pathological tendons, could be an evidence of re-injury and recent healing response.

Peripheral snap-fit locking mechanisms and smooth surface finish of tibial trays reduce backside wear in fixed-bearing total knee arthroplasty.

Background and purpose - Severe backside wear, observed in older generations of total knee replacements (TKRs), led to redesign of locking mechanisms to reduce micromotions between tibial tray and inlay. Since little is known about whether this effectively reduces backside wear in modern designs, we examined backside damage in retrievals of various contemporary fixed-bearing TKRs. Patients and methods - A consecutive series of 102 inlays with a peripheral (Stryker Triathlon, Stryker Scorpio, DePuy PFC Sigma, Aesculap Search Evolution) or dovetail locking mechanism (Zimmer NexGen, Smith and Nephew Genesis II) was examined. Articular and backside surface damage was evaluated using the semiquantitative Hood scale. Inlays were examined using scanning electron microscopy (SEM) to determine backside wear mechanisms. Results - Mean Hood scores for articular (A) and backside (B) surfaces were similar in most implants-Triathlon (A: 46, B: 22), Genesis II (A: 55, B: 24), Scorpio (A: 57, B: 24), PFC (A: 52, B: 20); Search (A: 56, B: 24)-except the NexGen knee (A: 57, B: 60), which had statistically significantly higher backside wear scores. SEM studies showed backside damage caused by abrasion related to micromotion in designs with dovetail locking mechanisms, especially in the unpolished NexGen trays. In implants with peripheral liner locking mechanism, there were no signs of micromotion or abrasion. Instead, "tray transfer" of polyethylene and flattening of machining was observed. Interpretation - Although this retrieval study may not represent well-functioning TKRs, we found that a smooth surface finish and a peripheral locking mechanism reduce backside wear in vivo, but further studies are required to determine whether this actually leads to reduced osteolysis and lower failure rates.

Massive failure of TiNbN coating in surface engineered metal-on-metal hip arthroplasty: Retrieval analysis.

This article presents examination of a failed total hip replacement with surface engineered metal-on-metal (MoM) articulation. The implant was coated with a thin TiNbN film (Physical Vapor Deposition), and at retrieval 53 months after implantation the coating was abraded on weight-bearing part of the head and acetabular component. Scanning electron microscopy of bearing surfaces demonstrated multifocal crack formation, delamination of small film fragments, and formation of aggregates containing nanometer sized wear debris. We also observed coating damage in third body mechanism. Complex failure mechanism of TiNbN coating demonstrated in this study suggests insufficient bonding strength between the coating and substrate alloy and raise concerns regarding the use of such coatings in total hip arthroplasty with MoM bearing. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1043-1049, 2016.

Retrieval analysis of titanium nitride (TiN) coated prosthetic femoral heads articulating with polyethylene.

Data regarding in vivo performance of titanium nitride (TiN) coated prosthetic femoral heads is scarce, and available studies of older generations of implants demonstrated coating wear in vivo. That is why we conducted a retrieval analysis of 11 femoral heads (articulating in vivo for 1-56 months) with TiN film formed using physical vapor deposition (PVD), to verify if coating failure is a problem in contemporary implants. Retrieved implants were examined using scanning electron microscope, coating roughness was evaluated with a contact profilometer and adhesion was tested using a Rockwell HRC test according to VDI 3824 guideline. Although no gross failure of the TiN coating was observed in our retrievals, all implants had defects typical for PVD coatings, such as pinholes, small titanium droplets and blisters with delaminated coating. In some heads the coating was contaminated with small niobium (Nb) droplets uniformly scattered on the entire surface of the film. Presence of Nb contamination was associated with an increased number and area of other types of defects and poorer coating adhesion. In one component, subjected to multiple dislocations we found severe delamination and cracking of the coating, increased roughness and the presence of third bodies. Our results indicate, that although wear of the coating is lower than seen in older generations of implants, inconsistent quality of the TiN film among different implants indicates the need for strict monitoring of the manufacturing process.