Arthroplasty System Research Articles

Robotic-arm assisted unicompartmental knee arthroplasty system has a learning curve of 11 cases and increased operating time.

UKA has higher revision risk, particularly for lower volume surgeons. While robotic-arm assisted systems allow for increased accuracy, introduction of new systems has been associated with learning curves. The aim of this study was to determine the learning curve of a UKA robotic-arm assisted system. The hypothesis was that this may affect operative times, patient outcomes, limb alignment, and component placement. Between 2017 and 2021, five surgeons performed 152 consecutive robotic-arm assisted primary medial UKA, and measurements of interest were recorded. Patient outcomes were measured with Oxford Knee Score, EuroQol-5D, and Forgotten Joint Score at 6weeks, 1year, and 2years. Surgeons were grouped into 'low' and 'high' usage groups based on total UKA (manual and robotic) performed per year. A learning curve of 11 cases was found with operative time (p < 0.01), femoral rotation (p = 0.02), and insert sizing (p = 0.03), which highlighted areas that require care during the learning phase. Despite decreased 6-week EQ-5D-5L VAS in the proficiency group (77 cf. 85, p < 0.01), no difference was found with implant survival (98.2%) between phases (p = 0.15), or between 'high' and 'low' usage surgeons (p = 0.23) at 36months. This suggested that the learning curve did not lead to early adverse effects in this patient cohort. Introduction of a UKA robotic-arm assisted system showed learning curves for operative times and insert sizing but not for implant survival at early follow-up. The short learning curve regardless of UKA usage indicated that robotic-arm assisted UKA may be particularly useful for low-usage surgeons. Level III, Retrospective cohort study.

Clinical Results after Design Modification of Lospa Total Knee Arthroplasty System: Comparison between Posterior-Stabilized (PS) and PS Plus Types.

BackgroundLospa posterior-stabilized (PS) Plus type is a modified version of Lospa PS, in which the polyethylene insert shape is modified to reinforce stability and prevent patella-post impingement compared to Lospa PS. However, studies comparing the clinical and radiographic results of the two designs have not been reported yet. This study aimed to compare the clinical results of total knee arthroplasty (TKA) using the existing PS type and the modified Lospa PS Plus type.MethodsA retrospective study was performed on 558 knees of 342 patients who underwent TKA using the Lospa PS or PS Plus types and were followed up for at least 2 years. Cases were divided into two groups according to the implant used: 212 cases in the PS group and 346 cases in the PS Plus group. For clinical outcome assessment, knee range of motion (ROM), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, and Knee Society Score (KSS) were recorded before surgery and at the 2-year follow-up. Radiographic outcomes were evaluated according to the American Knee Society method. The incidence of postoperative complications and survival rates were compared between the two groups.ResultsBoth groups showed significant clinical improvement after surgery. The average KSS significantly improved from 53.4 points in the PS group and 52.3 points in the PS Plus group preoperatively to 91.3 points and 93.2 points after surgery, respectively (p < 0.001). The average WOMAC score improved from 50.4 points in the PS group and 52.3 points in the PS Plus group before surgery to 15.6 points and 14.8 points after surgery, respectively (p < 0.001). There was no significant difference between the two groups in ROM, the alignment of the lower limbs, and the implant position after surgery. The complication rates were also similar between the groups (p = 0.167).ConclusionsThe Lospa PS Plus model is a modified design that improves the post structure from the previous PS type. Compared to the PS type, the PS Plus type showed similar statistical results at 2-year follow-up and good clinical results. The short-term average survival rate was over 98%, showing promising results.

Conversion of anatomic total shoulder arthroplasty to reverse shoulder arthroplasty using a unique hybrid glenoid component: technique and preliminary results

Degenerative arthritis of the shoulder is a common condition that is successfully treated with anatomic total shoulder arthroplasty (TSA). Rotator cuff disease has evolved as a leading cause of failure of anatomic TSA, requiring revision to reverse shoulder arthroplasty (RSA). This revision procedure can be extremely complex, particularly if removal of a well-fixed glenoid component is necessary. This case series outlines the technique and preliminary clinical results of conversion of anatomic TSA to RSA utilizing both modular humeral and hybrid glenoid components. From July 2017 to December 2019, the senior author (PMC) performed 84 consecutive anatomic TSA procedures utilizing a modular humeral arthroplasty system and a unique hybrid glenoid component. Three cases (3/84, or 3.6%) required conversion from anatomic TSA to RSA because of postoperative traumatic rotator cuff failure. All modular revision cases were performed without humeral stem removal and with utilization of the existing, well-fixed hybrid glenoid central titanium peg as the foundation for glenoid component revision. Preoperative and postoperative American Shoulder and Elbow Surgeons scores, visual analog scale pain scores, forward flexion, and patient satisfaction were analyzed in this modular revision group. In addition, several perioperative variables including operative time, blood loss, and length of stay were compared between this modular revision group and a nonmodular anatomic TSA to RSA revision comparative cohort. At an average follow-up of 24 months, average active forward flexion, postoperative American Shoulder and Elbow Surgeons scores, and visual analog scale pain scores improved significantly compared with preoperative scores in the modular revision group. All three patients were satisfied with their outcome. The average total operative time (109 minutes vs. 154 minutes, P= .02), blood loss (183 cc vs. 500 cc, P= .08), and length of hospital stay (26.3 hours vs. 36.6 hours P < .05) were lower in the modular revision group than those in a nonmodular revision cohort. Revision of anatomic TSA to RSA utilizing a modular humeral system and a convertible hybrid glenoid component that does not require removal of a well-fixed central titanium peg which serves as the foundation for glenoid component revision was performed efficiently, safely, and successfully in three cases. This technique results in significantly improved clinical outcomes when revision to RSA is needed while potentially decreasing perioperative complications in the revision setting.

The MAKO robotic-arm knee arthroplasty system.

The Mako robotic arm knee arthroplasty system was initially indicated in unicompartmental knee arthroplasty followed by bicompartmental and total knee arthroplasty techniques. The system utilizes three elements: (1) Pre-op 3D CT based planning and image based intra-op navigation. (2) Pre-resection implant modifications with integrated alignment, implant position and gap data, and (3) A semi-constrained robotic arm assisted execution of bone resection with "haptic" boundaries, and cemented implants. This paper evaluates variable pre-op implant placement, and anatomic reference positioning; data entry with incorporation of alignment, implant congruency through range of motion, and gaps; bone resection with "haptic" boundaries, and final implant evaluation with kinetic sensors. The Mako system allowed for improved implant placement utilizing CT guidance, bone resection accuracy, flexibility for functional implant placement with gap balancing. When combined with kinetic sensors, there was improved rotation and soft tissue balance. The MAKO robotic system can assist the surgeon with anatomic landmarks, provides the flexibility for independent gap balance through implant and alignment refinement, and three-dimensional soft tissue balancing data to achieve functional stability. Registry data has shown improved outcome survivorship irrespective of the surgeons' volumes and learning curves.

Hip and knee joint arthroplasty results in Lithuania

Justinas Stučinskas1, Mantas Giedraitis1, Jonas Marcinkevičius1, Kazimieras Grigaitis1, Šarūnas Tarasevičius1, Alfredas Smailys1 1 Lithuanian University of Health Sciences, Academy of Medicine, Faculty of Medicine, Kaunas, Lithuania Abstract Introduction. The hip and knee joints are most often replaced joints both in Lithuania and around the world. Demonstrating excellent results in arthroplasty surgeries, expanding the list of indications and increasing life expectancy, the need for these surgeries is constantly growing. Orthopedic surgeons must know which implants and surgical techniques provide the best treatment results for their patients. Register data is very important for evaluating results at the national level. Therefore, in this article we will review the results of Lithuanian hip and knee arthroplasty and evaluate the quality of implants used in Lithuania according to international ratings. Methodology: the results of Lithuanian hip and knee arthroplasty were evaluated using the data of the Lithuanian Arthroplasty Register. The analysis included all patients who underwent hip or knee replacement surgery in 2011-2021 period. Survival curves showing the total frequency of revisions were calculated using the life table statistics method. Also, to evaluate the quality of implants used in Lithuania according to the ODEP (Orthopedic Data Evaluation Panel) rating. Results: from 2011 to 2021 performed 36,744 primary hip and 23,865 primary knee arthroplasty surgeries. Survival of hip arthroplasty 10 m. period was 94.96 percent (95 percent, confidence interval (CI) 94.47-95.40 percent) and the road was 96.54 percent (95 percent CI 96.17-96.87 percent). About 76 percent of hip arthroplasty systems and 90 percent of knee arthroplasty systems used in Lithuania have an ODEP rating. Conclusions: the results of Lithuanian hip and knee arthroplasty are good, the survival over a 10-year period is about 95 percent and is similar to the results of other countries with extensive experience. A large part of the implants used in Lithuania have an international ODEP evaluation rating. Keywords: hip arthroplasty, knee arthroplasty, register, implant survival.

Artificial intelligence assisted total hip arthroplasty for patients with Crowe type Ⅳ developmental dysplasia of the hip

To investigate the early effectiveness of artificial intelligence (AI) assisted total hip arthroplasty (THA) system (AIHIP) in the treatment of patients with Crowe type Ⅳ developmental dysplasia of the hip (DDH). The clinical data of 23 patients with Crowe type Ⅳ DDH who met the selection criteria between May 2019 and December 2020 were retrospectively analyzed. There were 3 males and 20 females, the age ranged from 44 to 74 years, with an average of 52.65 years. The absolute value of the lower limbs discrepancy before operation was (15.17±22.17) mm. The preoperative Harris score was 62.4±7.2. The AIHIP system was used for preoperative planning, and the operations were all performed via conventional posterolateral approach. Thirteen patients with difficulty in reduction during operation underwent subtrochanteric shortening osteotomy (SSOT). The operation time, hospital stay, and adverse events were recorded; Harris score was used to evaluate the function of the affected limb at 1 day before operation and 1 week and 6 months after operation; pelvic anteroposterior X-ray film was taken at 1 day after operation to evaluate the position of the prosthesis. The matching degree of prosthesis was evaluated according to the consistency of intraoperative prosthesis model and preoperative planning. The matching degree of acetabular cup model after operation was 16 cases of perfect matching, 4 cases of general matching (1 case of +1, 3 cases of -1), and 3 cases of mismatch (all of them were +2), the coincidence rate was 86.96%. The matching degree of femoral stem model was perfect matching in 22 cases and general matching in 1 case of -1, and the coincidence rate was 100%. One patient had a periprosthesis fracture during operation, and was fixed with a wire cable during operation, and walked with the assistance of walking aid at 6 weeks after operation; the rest of the patients walked with the assistance of walking aid at 1 day after operation. The operation time was 185-315 minutes, with an average of 239.43 minutes; the hospital stay was 8-20 days, with an average of 9.96 days; and the time of disengagement from the walking aid was 2-56 days, with an average of 5.09 days. All patients were followed up 6 months. All incisions healed by first intension, and there was no complication such as infection, dislocation, refracture, and lower extremity deep venous thrombosis; X-ray films at 1 day and 6 months after operation showed that the acetabular and femoral prostheses were firmly fixed and within the safe zone; the absolute value of lower limbs discrepancy at 1 day after operation was (11.96±13.48) mm, which was not significantly decreased compared with that before operation ( t=0.582, P=0.564). All osteotomies healed at 6 months after operation. The Harris scores at 1 week and 6 months after operation were 69.5±4.9 and 79.2±5.7 respectively, showing significant differences between pre- and post-operation ( P<0.05). At 6 months after operation, the hip function was evaluated according to Harris score, and 13 cases were good, 9 cases were fair, and 1 case was poor. AIHIP system-assisted THA (difficult to reposition patients combined with SSOT) for adult Crowe type Ⅳ DDH has high preoperative planning accuracy, easy intraoperative reduction, early postoperative landing, and satisfactory short-term effectiveness.

Patient Satisfaction, Functional Outcomes, and Implant Survivorship in Patients Undergoing Customized Cruciate-Retaining TKA.

Customized total knee arthroplasty (C-TKA) systems are becoming increasingly popular in patients with end-stage knee arthritis. Manufactured with use of patient data derived from computed tomography or magnetic resonance imaging, these systems aim to restore the individual bone anatomy of the patient by providing customized fit and geometries. This retrospective study investigated implant survivorship, patient satisfaction, and functional outcomes following C-TKA with a cruciate-retaining prosthesis. We retrospectively reviewed data from 540 knees in 433 patients who underwent C-TKA performed by a single surgeon at a single institution. Patient demographics, surgical variables, complications, and reoperations were evaluated. Follow-up evaluations were performed via a single telephone call to assess patient satisfaction, functional outcomes according to the Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR) questionnaire, and implant survivorship following C-TKA. Descriptive statistics were analyzed. At the time of C-TKA, the mean age was 71.8 years and the mean body mass index was 29.1 kg/m2. The mean follow-up was 2.8 years. Patient satisfaction was high, with 89% of C-TKA patients being either satisfied or very satisfied. The mean KOOS-JR was 82. There were 8 revisions (1.5%) at an average of 0.7 years after the index C-TKA; hence, there was an implant survivorship of 98.5%. To our knowledge, this was the largest retrospective study to date to report on patient satisfaction, functional outcomes, and implant survivorship following C-TKA. We observed a high satisfaction rate, satisfactory functional outcomes, and high implant survivorship at midterm follow-up. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

A ligament tensor-guided extramedullary alignment technique for distal femoral cut in total knee replacement: results at a minimum 3 years follow-up

Femoral intramedullary canal referencing is used by most knee arthroplasty systems for distal femoral cut; to avoid the opening of the femoral canal different solutions have been presented such as navigation, patient-specific instruments (PSI) or the use of an extramedullary device. The FuZion® system is a tensor device, created to merge the two main techniques for performing a total knee arthroplasty: the ligament balancing and measured resection techniques. Our idea was to use the tensor as an extramedullary cutting guide for the distal femoral cut, based on a 90° tibial resection. A total of 110 patients were operated on with this technique. Patients were evaluated with weight-bearing long-standing X-rays, knee a-p and lateral views, validated PROMs (Oxford Knee Score, EQ-5D and EQ-VAS), the Knee Society Scoring System (KSS) and the Forgotten Joint Score (FJS). Minimum follow up was 3years (range 38-50months). Complete results were available for 104 patients (5 were lost in follow up and 1 died). Significant improvements were registered for all the evaluated scores from pre-op to the final follow up. Pre-op long-standing X-rays showed 21 valgus knees (20%) with a mean HKA of 187.6° (± 3.2°), 70 varus knees (62%) with a mean 172.2° (± 3.7°) HKA and 19 neutrally aligned knees, with a mean HKA of 179.5° (0 ± 2°). The radiographic evaluation at 3months post-op showed 20 valgus knees (mean HKA 183.7° ± 1.5°), 67 varus knees (mean HKA 176.1° ± 1.8°) and 23 neutrally aligned knees with a mean HKA of 179.3° (0 ± 2°). At final follow up the survival rate was 100% for revision of the implant as the endpoint. With any reoperation as the endpoint Kaplan-Meier survival estimate showed a survival rate of 95.1% at 3years. This technique for performing a ligament driven alignment in total knee arthroplasty showed encouraging clinical outcomes at mid-term follow up leaving a residual deformity on the coronal plane.

Conversion to Reverse Total Shoulder Arthroplasty with and without Humeral Stem Retention: Mid-to Long-Term Results

Background: Over the past decade, conversion to Reverse Total Shoulder Arthroplasty (RTSA) has become the preferred treatment for revision of an Anatomic Hemi (HA) or Total Shoulder Arthroplasty (TSA). However, conversion of failed stemmed shoulder arthroplasty to RTSA is still a highly demanding procedure and carries unique technical challenges and risks. Questions/Purposes: This study aimed to analyze the mid- to long-term results after conversion of failed anatomical shoulder arthroplasty to RTSA and investigate whether preserving the humeral stem offers advantages over revising the humeral stem. Materials and Methods: Between 2005 and 2018, 99 hemiarthroplasties and 62 total shoulder arthroplasties (total =161 shoulders; 157 patients) were revised to RTSA without (n=47) or with (n=114) stem exchange. Complications and revisions were documented from medical and surgical records. Longitudinal pre- and post-operative clinical (Constant-Murley (CS) score, Subjective Shoulder Value (SSV)), and radiographic outcomes were assessed. Complete clinical and radiographic follow-up was available on 80% of shoulders (127 patients; 128 of 161 procedures, 46 without and 82 with stem exchange) at a minimum of 24 months and a mean of 70 months (range, 24 to 184 months). Results: Humeral stem retention was associated with a significantly reduced surgical time (193 min vs. 227 min, p=0.001, less blood loss (591 mL vs. 753 mL, p=0.037), less intraoperative complications (13% vs. 19%; Odds Ratio (OR), 1.4, p=0.32) and fewer subsequent reinterventions (19% vs. 28%; OR, 2.3, p=0.06). The complication/revision rate leading to drop out from the study was considerable in the stem revision group (ten patients; ten of 114 shoulders (9%)), but there were no complication-related dropouts in the stem-retaining group. Conclusion: Our findings suggest that humeral stem revision is associated with decreased surgical time, less blood loss, less intra- and postoperative complications, and a lower revision rate compared to humeral stem retention. Based on these findings, a shoulder arthroplasty system modularity offers substantial benefit if conversion to reverse total shoulder arthroplasty becomes necessary. Level of Evidence: Level III, therapeutic study.

Assessment of glenoid baseplate initial micromotion and fixation strength in reverse total shoulder arthroplasty designs using a direct shear force methodology.

In a reverse total shoulder arthroplasty, the altered glenohumeral joint center of rotation subjects the glenoid baseplate to increased shear forces and potential loosening. This study examined glenoid baseplate micromotion and initial fixation strength with the application of direct shear force in a Sawbone model. The reverse total shoulder arthroplasty systems examined were the DJO Reverse® Shoulder Prosthesis, the Exactech Equinoxe® Reverse System, and the Tornier AequalisTM Reverse Shoulder Prosthesis. Specimens were cyclically tested with increasing shear loads until 150 µm of displacement between the implant and glenoid was achieved, and subsequently until failure, classified as either 1 cm of implant/glenoid displacement or fracture. The average load withstood for the 150 µm threshold for DJO, Tornier, and Exactech was 460 ± 88 N, 525 ± 100 N, and 585 ± 160 N, respectively. The average total load at device failure for DJO, Tornier, and Exactech was 980 ± 260 N, 1260 ± 120 N, and 1350 ± 230 N, respectively. The Exactech implant design trended toward requiring more load to induce micromotion at each threshold and to induce device failure, most commonly seen as inferior screw pull out. This study proposes design features that may enhance fixation and suggests little risk of initial micromotion or failure during initial post-operative recovery.

Hip implants can restore anatomical and medialized rotation centres in most cases : a 3D templating study comparing four implantation strategies.

AimsHip arthroplasty does not always restore normal anatomy. This is due to inaccurate surgery or lack of stem sizes. We evaluated the aptitude of four total hip arthroplasty systems to restore an anatomical and medialized hip rotation centre.MethodsUsing 3D templating software in 49 CT scans of non-deformed femora, we virtually implanted: 1) small uncemented calcar-guided stems with two offset options (Optimys, Mathys), 2) uncemented straight stems with two offset options (Summit, DePuy Synthes), 3) cemented undersized stems (Exeter philosophy) with three offset options (CPT, ZimmerBiomet), and 4) cemented line-to-line stems (Kerboul philosophy) with proportional offsets (Centris, Mathys). We measured the distance between the templated and the anatomical and 5 mm medialized hip rotation centre.ResultsBoth rotation centres could be restored within 5 mm in 94% and 92% of cases, respectively. The cemented undersized stem performed best, combining freedom of stem positioning and a large offset range. The uncemented straight stem performed well because of its large and well-chosen offset range, and despite the need for cortical bone contact limiting stem positioning. The cemented line-to-line stem performed less well due to a small range of sizes and offsets. The uncemented calcar-guided stem performed worst, despite 24 sizes and a large and well-chosen offset range. This was attributed to the calcar curvature restricting the stem insertion depth along the femoral axis.ConclusionIn the majority of non-deformed femora, leg length, offset, and anteversion can be restored accurately with non-modular stems during 3D templating. Failure to restore hip biomechanics is mostly due to surgical inaccuracy. Small calcar guided stems offer no advantage to restore hip biomechanics compared to more traditional designs.Cite this article: Bone Jt Open 2021;2(7):476–485.

The Agility Total Ankle Arthroplasty: A Concise Follow-up at a Minimum of 20 Years.

Between 1984 and 1994, a single surgeon performed 132 primary cementless total ankle replacements using the Agility total arthroplasty system. The purpose of this study was to report on the 20-year follow-up, which we believe is the first study with this length of follow-up. Living patients were contacted and interviewed to determine the status of their implant (revised or unrevised) and to answer a simple questionnaire concerning overall satisfaction, pain, and functional improvement, as in a previous study. Thirty-three (26.2%) patients with 33 (25%) ankles of the original series were alive at a minimum of 20 years postoperatively, with a median follow-up of 22 years. They were asked to return to the office for standing anteroposterior and lateral ankle and foot radiographs or to send these radiographs if performed elsewhere. Radiographs were evaluated for radiolucencies around the components and subsidence (talar component) or migration (tibial component) of components. Seventeen (13.5%) ankles of the 126 available for follow-up, including 5 (15.2%) ankles in living patients, had undergone revision (n = 10) or arthrodesis (n = 7) for loosening. One additional ankle was revised for infection and 1 for talar component malposition; thus, 19 (15.1%) ankles were revised. These results should provide a 20-year benchmark for newer total ankle arthroplasty designs when a similar length of follow-up becomes available. Level III, retrospective cohort study.

Nontribological corrosion modes dominate wrought CoCrMo acetabular taper corrosion: A retrieval study.

Corrosion of modular metal-on-metal acetabular tapers in total hip arthroplasty (THA) systems is often attributed to mechanically driven processes. Recent findings suggest that mechanically assisted crevice corrosion (MACC) might not be the dominant cause of corrosion in shell-liner tapers. This study aims to document and present the corrosion modes observed in metal-metal acetabular liners. Twenty-one retrieved wrought CoCrMo liners were examined using digital optical microscopy (DOM), scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). Corrosion-related damage was documented in nonengagement taper regions, outside of direct taper contact. Within engagement regions, nonmechanically driven corrosion features (pitting, intergranular corrosion) were observed adjacent to fretting and material transfer, which rely on mechanical contact; corrosion independent of MACC was observed even in contact regions. Corrosion types observed included intergranular corrosion (IGC), pitting attack, phase boundary dissolution, all both outside and inside of taper junctions, and MACC within contact regions of the taper. Typical fretting scars associated with MACC were mostly absent, and were not always associated with corrosion damage where present. Finally, hard phase particles (Mo-Si-O) released from the wrought CoCrMo microstructure had redeposited within regions with material loss. Acetabular taper corrosion modes differ significantly from those in head-neck tapers and are dominated by electrochemically driven processes, not mechanical processes, as indicated by corrosion in noncontact regions. With greater prevalence of dual mobility hip implants, acetabular taper corrosion processes must be understood in order to limit their impact on device performance.

The Use of Computer Navigation and Robotic Technology in Complex Total Knee Arthroplasty.

The potential benefits of computer-assisted surgical (CAS) navigation and robotic total knee arthroplasty (TKA) systems, such as increased reliability of restoring the mechanical axis, fewer outliers, more rapid hospital discharge, less physical therapy requirements, decreased blood loss, and decreased revision rates, have led to their application not only in primary cases but also in complex cases such as preoperative deformity and revision. Early evidence demonstrates that CAS navigation may help to improve alignment in complex cases of femoral and tibial deformity and in cases of femoral bowing. Data regarding deformity correction with robotic systems are similar to CAS navigation with regard to alignment, but are more limited. There are also scant data regarding revision cases and cases of previous intramedullary canal instrumentation. Concerns remain regarding cost, learning curves, and operative times. There are potential long-term cost savings associated with a decrease in revisions and readmissions that require additional investigation. Early evidence for the use of these emerging technologies for deformity correction and revision cases is promising, but their impact on long-term functional outcomes remains to be demonstrated. Additional well-designed comparative studies are warranted.

Quantification of assembly forces during creation of head-neck taper junction considering soft tissue bearing: a biomechanical study

BackgroundAll current total hip arthroplasty (THA) systems are modular in design. Only during the operation femoral head and stem get connected by a Morse taper junction. The junction is realized by hammer blows from the surgeon. Decisive for the junction strength is the maximum force acting once in the direction of the neck axis, which is mainly influenced by the applied impulse and surrounding soft tissues. This leads to large differences in assembly forces between the surgeries. This study aimed to quantify the assembly forces of different surgeons under influence of surrounding soft tissue.MethodsFirst, a measuring system, consisting of a prosthesis and a hammer, was developed. Both components are equipped with a piezoelectric force sensor. Initially, in situ experiments on human cadavers were carried out using this system in order to determine the actual assembly forces and to characterize the influence of human soft tissues. Afterwards, an in vitro model in the form of an artificial femur (Sawbones Europe AB, Malmo, Sweden) with implanted measuring stem embedded in gelatine was developed. The gelatine mixture was chosen in such a way that assembly forces applied to the model corresponded to those in situ. A study involving 31 surgeons was carried out on the aforementioned in vitro model, in which the assembly forces were determined.ResultsA model was developed, with the influence of human soft tissues being taken into account. The assembly forces measured on the in vitro model were, on average, 2037.2 N ± 724.9 N, ranging from 822.5 N to 3835.2 N. The comparison among the surgeons showed no significant differences in sex (P = 0.09), work experience (P = 0.71) and number of THAs performed per year (P = 0.69).ConclusionsAll measured assembly forces were below 4 kN, which is recommended in the literature. This could lead to increased corrosion following fretting in the head-neck interface. In addition, there was a very wide range of assembly forces among the surgeons, although other influencing factors such as different implant sizes or materials were not taken into account. To ensure optimal assembly force, the impaction should be standardized, e.g., by using an appropriate surgical instrument.

A new robotically assisted system for total knee arthroplasty: A sheep model study.

We investigated the accuracy and safety of a new HURWA robotic-assisted total knee arthroplasty (TKA) system in a sheep model. Ten male small-tailed Han sheep were used in this study. Sheep were imaged by computed tomography scan before and after bone resection and the cutting errors between actual bone preparation and preoperative planning of the femur and tibia in three dimensions were measured. The overall accuracies after surgery compared with that from preoperative surgical planning of the left and right femurs were 1.93±1.02° and 1.93±1.23°, respectively. Additionally, similarly high overall accuracies for the left and right tibia of 1.26±1.04 and 1.68±0.92°, respectively, were obtained. The gap distances of the distal cut, anterior chamfer, anterior cut, posterior chamfer and posterior cut on the medial side were 0.47±0.35mm, 0.41±0.37mm, 0.12±0.26mm, 0.41±0.44mm and 0.12±0.23mm, respectively. No intraoperative complications, such as intraoperative fracture, massive bleeding or death, occurred. This new HURWA robotic-assisted TKA system is an accurate and safe tool for TKA surgery based on the sheep model.

The area method for measuring acetabular cup anteversion: An accurate and autonomous solution

Several radiological methods of measuring anteversion of the acetabular component after total hip arthroplasty have been described, all time-consuming and with varying reproducibility. This study aimed to compare the recently proposed Area method to true cup anteversion as determined by an accelerometer. This study further applied this method programmatically to autonomously determine radiographic cup orientation using two computer programs, then compared these results to hand and accelerometer measurements. 160 anteroposterior pelvis radiographs were taken of a standard Sawbones® pelvis fitted with a total hip arthroplasty system. The acetabular cup was re-oriented between each radiograph, with anteversion ranging from 0° to 90°. An accelerometer was mounted to the cup to measure true cup anteversion. Radiographic anteversion was independently measured via three methods: by hand, linear image processing, and machine learning. Measurements were compared to triaxial accelerometer recordings. Coefficient of determination (R2) was found to be 0.997, 0.991, and 0.989 for hand measurements, the machine learning, and linear image processing, respectively. The machine learning program and hand measurements overestimated anteversion by 0.70° and 0.02° respectively. The program using linear techniques underestimated anteversion by 5.02°. Average runtime was 0.03 and 0.59 s for the machine learning and linear image processing program, respectively. The machine learning program averaged within 1° of cup orientation given a true cup anteversion less than 51°, and within 2° given an anteversion less than 85°. The Area method showed great accuracy and reliability with hand measurements compared to true anteversion. The results of this study support the use of machine learning for accurate, timely, autonomous assessment of cup orientation.

Complications of proximal humeral fractures

Objective. Proximal humeral fractures are among the most frequent fracture in the adult and their treatment is controversial.The purpose of this paper is to present the most common complications in managing prox- imal humeral fractures, reviewing the literature.The principal complications are mainly caused by biological elements, but are also related to iatrogenic factors.Conclusions. It is very important to provide a correct fracture classification, accurate pa- tient clinical investigation, and to perform all instrumental procedures required to get a correct indication in managing proximal humeral fracture. In case of operative treatment, accurate pre-operatory planning is mandatory. Moreover, the surgeon must consider the feasible intra-operatory complications, such as the possibility to convert an open reduction and internal fixation to a total arthroplasty.In our opinion, the arthroplasty system should be available in every operating theater.

A cadaveric experimental study on domestic robot-assisted total knee arthroplasty

To simulate and validate the performance, accuracy, and safety of the Yuanhua robotic-assisted total knee arthroplasty system (YUANHUA-TKA) through cadaver-based experiment, thus optimizing the robotic system for the future human clinical application. Six unilateral adult cadaver specimens of the lower limbs were scanned by three-dimensional CT before the experiment, and then the three-dimensional models of femur and tibia were obtained by using the preoperative software of YUANHUA-TKA system, so as to plan the type of prosthesis implant, the osteotomy volume and osteotomy angles [hip-knee-ankle angle (HKA), coronal frontal femoral component (FFC) and frontal tibial component (FTC)], the ideal value of HKA was set to 180°, and of FFC and FTC were set to 90°, respectively. The operator could further confirm the osteotomy plan according to the intraoperative situation before osteotomy, and then install the prosthesis after completing the osteotomy in each plane with the assistance of YUANHUA-TKA system. At last, the X-ray films of hip joint, knee joint, and ankle joint were taken and stitched into the full length X-ray film of the lower limb, and HKA, coronal FFC and FTC were measured. During the experiment, YUANHUA-TKA system ran stably. All sections of femur and tibia were smooth and no ligament injury was found. After operation, the HKA was 177.1°-179.7°, FFC was 87.9°-91.4°, and FTC was 87.3°-91.4°, which were within ±3° from the ideal values of preoperative planning. The YUANHUA-TKA system can assist the surgeon to carry out precise osteotomy according to the preoperative planned value, which has a good auxiliary effect for total knee arthroplasty. It is expected to assist joint surgeons to improve the surgical accuracy in clinical application.

Total Ankle Replacement Requiring Distal Tibiofibular Arthrodesis in a Dog

AbstractThis case report describes distal tibiofibular arthrodesis as a technique for achieving increased confluent bone support for the placement of oversized arthroplasty components for talocrural arthroplasty in an 18-month-old Labrador Retriever with talocrural osteoarthritis secondary to talar osteochondrosis. Computed tomography assessment for suitability for BioMedtrix canine ankle replacement surgery revealed the tibia to be undersized relative to the tibial component. Distal tibiofibular arthrodesis was performed to increase lateral bone support to permit placement of an otherwise oversized prosthesis. Subjective assessment of outcome with owner Liverpool Osteoarthritis in Dogs questionnaire to 6 months postoperatively as well as radiological assessment to 4 months postoperatively documented significant improvement in lameness in the operated limb with no complications. Distal tibiofibular arthrodesis is a means by which to achieve increased bone support prior to BioMedtrix canine total ankle replacement surgery. The surgical technique described herein permitted placement of an oversized talocrural prosthesis in this patient with good clinical function. This technique may permit use of this arthroplasty system in otherwise undersized patients until such a time that smaller implants are available from the manufacturer.