Trial Prosthesis Research Articles

Cementless Long-Stem Reverse Total Shoulder Arthroplasty as Primary Treatment for Metadiaphyseal Humeral Shaft Fractures.

The use of cementless diaphysis-fitting stems has been shown to be an effective treatment option for cases of metadiaphyseal humeral fracture. Complex metadiaphyseal fractures are those that extend below the surgical neck into the diaphysis, which can compromise the metaphyseal fixation of typical arthroplasty designs. The presently described surgical technique circumvents the potential risks associated with the use of cement while also permitting the treatment of common concomitant pathologies, such as arthritis and rotator cuff tendinopathy. Evidence supports the efficacy of this technique, showcasing consistent rates of healing, pain relief, and functional recovery, as well as acceptable complication rates compared with alternative surgical options. The surgical procedure is performed with the patient in a modified beach chair position. A deltopectoral approach is utilized in order to expose the humerus and glenoid. In cases in which the tuberosity is fractured, it is carefully tagged for subsequent repair. The metadiaphyseal extension of the fracture is exposed, and reduction is performed with cerclage cable augmentation as needed. When direct reduction proves challenging, the humeral prosthesis is utilized to aid in reduction. Full-length humeral radiographs and a humeral sounder are utilized to guide the placement of a trial prosthesis, ensuring that the stem spans 2 canal diameters past the fracture and restores the appropriate humeral length. The medullary stem is utilized as support for fracture fragment reduction, with use of a combination of bone stitching and cerclage cables as required. Fractures with compromised proximal humeral bone stock can be further augmented with extramedullary strut allografts and cerclage cables. The allograft strut fixation acts as a neutralization plate to maintain rotational control. The joint is reduced, and fixation of the subscapularis and tuberosity is achieved with use of a transosseous suture technique. This technique combines the use of arthroplasty as well as standard osteosynthesis principles to treat complex metadiaphyseal humerus fractures. Nonoperative treatment may be indicated in a primary setting and represents a multifactorial patient-specific decision. Other surgical options include open reduction with internal fixation with plates or an intramedullary humeral nail, and cemented long-stem arthroplasty. If the fracture is too distal and the surgeon is unable to achieve a length of 2 canal diameters for distal fixation, alternative treatment strategies such as cementation may be required. This procedure is most often performed in elderly patients with osteoporosis, who often also have comminuted fracture patterns and conditions such as glenohumeral arthritis or chronic rotator cuff pathology1,5,6,13,15. Whereas open reduction and internal fixation (ORIF) can be effective in younger patients, it poses higher risks of complications in patients with osteoporosis1,3,9,14-16. Neither ORIF nor intramedullary nailing addresses concurrent pathologies. Another alternative technique involves the use of a cemented stem; however, a cementless approach eliminates theoretical risks of cement use, allows easier revisions, and achieves comparable outcomes9,16,20. In summary, cementless long-stem RTSA offers consistent healing rates, satisfactory outcomes, and favorable results. Cementless long-stem reverse total shoulder arthroplasty (RTSA) is a viable alternative for elderly patients with metadiaphyseal proximal humeral fractures. This technique shows consistent healing rates, pain relief, shoulder function restoration, and an acceptable complication rate. In a study of 14 patients who underwent cementless long-stem RTSA from September 2017 to August 2020, all patients showed improved outcomes and radiographic evidence of union at an average of 13 months postoperatively. Minor complications have been reported, such as transient neuropathy, tuberosity nonunion, and humeral stress shielding. This technique is optimal for elderly patients with osteoporotic bone, comminuted fractures, glenohumeral arthritis, and/or rotator cuff pathology.Long comminuted fractures require bridging fixation, spanning 2 canal diameters beyond the fracture site.Patients with compromised proximal humeral bone stock may require allograft strut augmentation.The surgical principle integrates standard arthroplasty for joint length restoration, a relative fracture stability concept by spanning complex fracture segments, and an absolute stability concept by direct fragment alignment. RTSA = reverse total shoulder arthroplastyIMN = intramedullary nailORIF = open reduction and internal fixationAVN = avascular necrosisAP = anteroposteriorCT = computed topographyTSA = total shoulder arthroplastyXR = plain radiographsFU = follow-upSST = simple shoulder testASES = American Shoulder and Elbow SurgeonsDASH = Disabilities of the Arm, Shoulder and HandPROM = patient-reported outcome measuresROM = range of motion.

Difference in the Extension Gap Between Osteoarthritis and Osteonecrosis in Medial Fixed-Bearing Unicompartmental Knee Arthroplasty with the Spacer Block Technique.

The spacer block technique is widely used in medial fixed-bearing unicompartmental knee arthroplasty (UKA) for osteoarthritis (OA) and osteonecrosis (ON), while it is still unclear if there is any difference in the extension gap between UKAs for the two conditions. To clarify the question, the data from 87 consecutive patients (OA: 57 patients and ON: 30 patients) who underwent medial fixed-bearing UKA with the spacer block technique were retrospectively collected and analyzed. The component gap between the medial tibial osteotomy surface and the femoral trial prosthesis in extension was measured using a UKA tensor, and the preosteotomy gap was calculated in each condition. Also, pre- and postoperative coronal hip-knee-ankle (HKA) angles, the thickness of the insert, and the amount of distal femoral and proximal tibial osteotomy were measured and compared between the two groups. As a result, the mean preosteotomy gap in Group OA and Group ON was 5.4 and 3.7 mm, respectively (p < 0.001). The amount of change in HKA angle following UKA in Group OA and Group ON was 4.4and 3.8 degrees, respectively (p = 0.044), while no significant difference was found regarding pre- and postoperative HKA angle between them. Also, thinner inserts tended to be used in Group ON than in Group OA, while no significant difference in the amount of osteotomies was found between them. Since knees with OA and ON showed different biomechanical conditions at medial fixed-bearing UKA probably for the difference in the amount of remaining cartilage, the surgical technique should be carefully considered for each condition.

Cementing a Monoblock Dual-Mobility Implant into a Fully Porous Cup in Revision Total Hip Arthroplasty to Address Hip Instability: Surgical Technique.

Cementing a Monoblock Dual-Mobility Implant into a Fully Porous Cup in Revision Total Hip Arthroplasty to Address Hip Instability: Surgical Technique.

The influence of patellar height on patellofemoral contact force during total knee arthroplasty

PurposeResidual anterior knee pain following total knee arthroplasty was reported to be related to high patellofemoral contact force. This study tried to show the relationship between patellar height and patellofemoral contact force in vivo, which has been demonstrated only in vitro thus far. MethodsFifty-five patients who had undergone a primary mobile-bearing posterior-stabilized total knee arthroplasty (28 cases using PFC Sigma and 27 cases using Attune) were included. After all the trial prostheses were placed, the patellar contact forces on the medial and lateral sides were measured using specially designed two uniaxial ultrathin force transducers at 0°–135° of knee flexion guided by the navigation system. Correlations between the pre-operative Insall-Salvati index and the medial or lateral patellar contact force in each flexion angle were analyzed using linear regression. Correlations between each patellar contact force and postoperative flexion angle were also assessed. ResultThere was a positive correlation between Insall-Salvati index and the lateral patellar contact force at 135° of flexion in all the patients, at 120° and 135° of flexion in patients with PFC Sigma and 135° of flexion in patients with Attune. The lateral patellar contact force at 120° and 135° of flexion in patients with PFC Sigma inversely correlated with postoperative flexion angle. ConclusionsPatients with patella alta tended to demonstrate high lateral patellar contact force in deep knee flexion after total knee arthroplasty, which can affect the post operative flexion angle and should be treated to prevent residual anterior knee pain.

Quantifying 30 Years of Technological Innovation in Total Hip Arthroplasty

AbstractTechnological innovation in total hip arthroplasty (THA) is a critical component of health care delivery for improving patient outcomes. Analyzing the content of patents and trends in their activity over time can leverage insight into innovations in THA; however, these investigations remain underutilized. We aimed to quantify patent activity and relative growth pertaining to technologies in THA over a 30-year period. A query for patents relating to “hip replacement” or “hip arthroplasty” between 1989 and 2019 using an open-source patent database yielded 24,071 unique patents for analysis. These were grouped into 12 independent technology clusters using Cooperative Patent Classification codes. Annual patent activity for each cluster was normalized with a validated formula to control for exponential growth. The 5-, 10-, and 30-year compound annual growth rates (CAGR) for each cluster were quantified and compared between clusters. Annual cumulative patent activity increased from 151 patents in 1989 to 1,182 patents in 2019, representing a 682.8% increase. The largest technology clusters concerned “drugs” (n = 6,429 patents), “instruments” (n = 4,014 patents), “materials” (n = 2,037 patents), and “components” (n = 1,946 patents). One-half of the identified clusters concerned developments in technology-assisted THA (patient-specific instrumentation, navigation, robotics, design/manufacturing, instruments, and computer modeling). The most rapidly growing technology within the past 5, 10, and 30 years was robotics (CAGR = 15.82%, 20.11%, and 9.50%, respectively). Within the past 5- and 10-year trial prostheses (CAGR = 10.76%) and design/manufacturing processes (CAGR = 10.27%), computer modeling (CAGR = 12.91%) and navigation (CAGR = 11.25%) were among the most rapidly growing clusters, respectively. The majority of patents pertaining to THA over the past 30 years have concerned developments in drugs, instruments, materials, and components. Within the past 10-years, substantial growth has been observed in patent domains related to technology-assisted THA. Monitoring of emerging technologies through patent metrics may provide valuable information for regulatory bodies and assess progress in the field of THA. This is a cross-sectional study with level of evidence IV.

Surgeon-performed pericapsular nerve group (PENG) block for total hip arthroplasty using the direct anterior approach: a cadaveric study

BackgroundDuring total hip arthroplasty (THA) using the direct anterior approach, orthopaedic surgeons can identify all anatomical landmarks required for pericapsular nerve group (PENG) blocks and carry out the latter under...

Preoperative varus deformity of the knee affects the intraoperative joint gap in unicompartmental knee arthroplasty

BackgroundIt is generally believed that contraction of the soft tissue structures on the medial side may occur in the knee with severe varus deformity. However, the relationship between the severity of varus deformity of the knee and the intraoperative soft tissue balance in unicompartmental knee arthroplasty (UKA) has not been well reported thus far. MethodsOne hundred and three consecutive medial UKAs were enrolled. After the femoral trial prosthesis was placed, the component gap was measured at 10° (extension) and 120° (flexion) of flexion using a UKA tensor. The pre-osteotomy gap was then calculated from the thickness of the bone cut. Paired Student’s t-test was used to compare the component gap, as well as the pre-osteotomy gap, in extension and those in flexion. The relationship between the preoperative Hip-Knee-Ankle (HKA) angle and the pre-osteotomy gap was analysed using Pearson’s correlation coefficient and simple linear regression analysis. ResultsThe component gap in extension was significantly smaller than that in flexion while the pre-osteotomy gap in extension was significantly wider than that in flexion. There was a positive correlation between the severity of varus deformation in preoperative knee and the pre-osteotomy gap in extension, while there was no correlation between the preoperative HKA angle and the pre-osteotomy gap in flexion. ConclusionsThe tension of the medial tightness does not correlate with the degree of preoperative varus deformity in UKA.

Three-step technique for implantation of rotating hinge knee prostheses : Demonstration using the Enduro prosthesis.

Implantation of an axis-guided knee prosthesis with consideration of the joint line and balanced flexion and extension gap to reduce the mechanical load on the prosthesis axis and to improve the movement of the prosthesis. Distinct unilateral instability due to ligament insufficiency in association with knee prostheses. Primary implantation of axis-guided knee prostheses with pronounced axial malalignment (>20-25° valgus or varus malalignment) or/and severe flexion contracture > 40°. Replacement of prosthesis with nonsignificant imbalance between flexion and extension gap. Clearly unstable flexion gap such that the extension gap cannot be adjusted appropriately. Significant femoral bone defects requiring distal femoral replacement prostheses. Reconstruction of the tibial platform with the trial prosthesis with regard to height in relation to the tip of the fibula. Determination of the femoral prosthesis size. Adjustment of the anteroposterior (AP) cutting block of the selected size, referenced anteriorly and in correct rotation. Determination of the flexion gap with spacers using the stable side of the collateral ligaments. Positioning the distal cutting block and determination of the height of the extension gap. Moving the distal cutting block until the same height of spacer as used in the flexion gap fits into the extension gap, taking into account the stable side of the collateral ligaments. The extent of the displacementD1 is noted. Reverse displacement of the distal cutting block by the distanceD2 until asatisfactory bony contact surface for the femoral component in the distal femur can be created. The thickness of the required distal augments on the following chamfer-cutting guide (4-in‑1 cutting block) and thus on the femoral prosthetic component is the sum of D1 + D2. The chamfer-cutting guide (4-in‑1 block) with distal augments of the calculated height (D = D1 + D2) is placed in position. Definition and preparation of the posterior contact surface with positioning of any necessary posterior augments. Completion of the femoral preparation taking into account the distal and posterior augments. Assembly of the trial prostheses with atrial inlay having the height of the spacers used. Implantation of the selected prosthesis components. Thrombosis prophylaxis, physiotherapy under full weight-bearing and mobility exercises. After implantation of 104 axis-guided Enduro™ knee prostheses (Aesculap AG, Tuttlingen, Germany) (73knee prosthesis revisions and 31 primary implantations), the Knee Society Score increased from 42.8 ± 18.8 preoperatively to 84.8 ± 13.9 after 24months. Complications comprised one deep vein thrombosis and one periprosthetic infection.

Instrumented Trial Prosthesis for Intraoperative Measurements of Joint Reaction Forces during Reverse Total Shoulder Arthroplasty

Instrumented Trial Prosthesis for Intraoperative Measurements of Joint Reaction Forces during Reverse Total Shoulder Arthroplasty

Evaluation of Dimensional Stability for Denture Bases in different Curing Techniques

Stable record base is critical for recording an accurate maxillo-mandibular relationship and evaluation of the esthetics and phonetics of the wax trial prosthesis. To ensure intra-oral stability and retention of the record base, the base should maintain close adaptation to the cast and be dimensionally stable, this study compare the dimensional stability of visible light cure acrylic both conventionally and by using new technique of short curing cycle. Thirty maxillary cast edentulous models poured with a type IV dental di-stone, the specimen divided into three subgroups each group consist of ten cast. In the first group denture base constructed from heat cure acrylic resin using short curing cycle, while in the second group it constructed by using visible light cure acrylic resin and for the third group from visible light cure acrylic resin using new technique, the gap space occurs between the denture base and the cast measured by using traveling microscope measuring device. In this study the reading for the gap space occur between the denture base and the cast show that significantly both the short cycle and VLC new technique more dimensionally stable than that of VLC conventional technique when compared by ANOVA Table and LSD multiple comparison. The dimensional accuracy or fit for the denture base improved by using either a heat cured acrylic resin (using short curing cycle or by using light activated poly methylmethacrylate with the aid of new technique so that better stability and retention of the record bases obtained.

The medial tibial joint line elevation over 5mm restrained the improvement of knee extension angle in unicompartmental knee arthroplasty.

The purpose of this study was to examine the relationship between medial tibial joint line elevation and the improvement of range of motion (ROM) in unicompartmental knee arthroplasty (UKA). The hypothesis was that limited elevation of tibial joint line will improve knee range of motion in UKA. Forty-six consecutive medial UKAs were enrolled in this study. Medial tibial joint line elevation was defined as the polyethylene insert and tibial tray thickness minus the tibial osteotomy and sawblade thickness. Positive values indicated an elevation of the tibial joint line. A component gap between the femoral trial prosthesis and the medial tibial osteotomy surface was also examined. Joint loosening was also calculated based on the joint component gap minus insert and tibial tray thickness. The correlation of the medial tibial joint line elevation with joint looseness and postoperative range of motion were analyzed. The mean medial tibial joint line elevation was 4.9 ± 1.1mm. The medial tibial joint line elevation reduced the improvement of knee extension (R = - 0.43, p < 0.01). The medial tibial joint line elevation was also correlated with reduced loosening of the joint knee extension (R = - 0.42, p < 0.01). This, in turn, resulted in limited improvement of the knee extension angle. Moreover, joint line elevation under 5mm significantly improved knee extension angle compared to joint line elevation over 5mm. The medial joint line elevation of the tibia in UKA reduced the improvement of knee extension angle, due to a reduced joint looseness at knee extension. A tibial joint line elevation greater than 5mm in UKA should be avoided to prevent postoperative flexion contracture. For the clinical relevance, this study clarified that the medial joint line of the tibia is an important factor to prevent postoperative flexion contracture in UKA. II.

The first experience with the implantation of the prosthesis xenopericardial frame variable stiffness "Tiara" in the aortic position

Represents the results of a clinical trial implantation xenopericardial prosthesis mounted on a frame of variable stiffness "Tiara" in the aortic position. Prosthesis implanted in a single-row suture cubcoronary supraannulary position. Implantation performed two patients 71 and 75 years with a good clinical outcome. According to the control echocardiography peak gradients at rest were 9-15 mm Hg. According to the results of a clinical trial prosthesis can be recommended for implementation in everyday clinical practice.

A Development of Force Distribution Measurement System with High Resolution for Total Knee Arthroplasty

Soft tissue or ligament balancing in total knee arthroplasty is important for ensuring knee joint stability. Correct balancing and appropriate alignment of ligaments extend prosthesis life by preventing unnecessary force fromacting on the prosthesis during routine activities. The current implementation of total knee arthroplasty relies heavily on the subjective “feel” of the surgeon for correct prosthesis implantation onto tibiofemoral components. We developed a force distribution sensing systemto provide quantitative information to surgeons during ligament balancing. The measurement system consists of two main components: two force sensors embedded in trial insert for each condyle and signal acquisition for data processing and force visualization. Sensors were designed and developed using pressure-sensitive conductive rubber that measures changes in resistance in the event of deformation caused by external force. Corresponding voltage measured by circuits is transmitted via an RF transceiver to a computer and visualized as color gradient. Current sensors could measure maximum force of 196.13 N (20 kgf). Results from calibration and experiments on a plastic trial prosthesis indicated that the device has good potential for providing appropriate force distribution information on the knee during total knee arthroplasty procedure.

Anterior Intrapelvic Migration of Femoral Trial Head Requiring Secondary Surgical Approach for Retrieval

The current report describes a revision total hip arthroplasty in which the trial femoral head disassociated during reduction and migrated into a soft tissue capsule of the true pelvis between the external iliac vein and corona mortise. The authors believe this previously undescribed migration pattern was created by the patient's history of recurrent dislocations. To retrieve the trial prosthesis without injuring the adjacent vasculature, a secondary surgical approach was utilized. The described case identifies the risk of pelvic migration in patients with a history of dislocations and reminds us that a secondary surgical approach should be considered to avoid devastating injury to the neighboring vasculature.

Computer Navigation of Soft Tissues in Total Knee Replacement

Following the success of computer navigation in producing consistently accurate alignment, the focus has shifted to use of these techniques for soft tissue assessment during total knee replacement (TKR). We undertook a prospectively randomized clinical study to compare two methods of tissue balancing in TKR. One method, called bone referencing (BR) employed independent cutting of the femur and tibia followed by subjective assessment with trial prostheses and soft tissue release as deemed necessary. The other method, termed ligament balancing (LB), involved cutting the tibia first and titration of tissue balance and alignment parameters to guide femoral cuts. Our total sample comprised 77 subjects with 80% statistical power. To assess tissue balance we used (a) coronal laxity testing and (b) computer navigation generated passive knee range of movement graphs. The graphical assessment was validated with coronal laxity testing. There was no difference between the resultant tissue balances achieved. However, correlation with preoperative status revealed the LB technique to show better results in a smaller subgroup of knees with greater preoperative tissue imbalance. We advocate variation of tissue balancing technique to suit the individual knee, based on preoperative assessment, to achieve an optimal result in all TKR.

Rekonstruktion des distalen Radioulnargelenks mit der Herbert-Ulnakopfprothese

To provide painfree forearm rotation in patients with degenerative changes of the distal radioulnar joint (DRUJ). The primary goal is to stabilize the DRUJ in patients with an unstable stump of the distal ulna following resection arthroplasty with the secondary effect of restoring painfree forearm rotation. Instability of the distal ulna following various types of resection arthroplasties. Primary or secondary osteoarthritis of the DRUJ. Replacement of an ulnar head destroyed by tumor or trauma. Longitudinal instability of the forearm (e.g., following an Essex-Lopresti-type of injury, resection of the radial head). Inadequate soft tissue with severe ulnocarpal ligamentous insufficiency. Radial deformity (must be corrected before replacement of the ulnar head). In cases of osteoarthritis of the DRUJ, dorsal exposure of the distal radioulnar joint to the depth of the 5th extensor compartment. Raising of an ulnar-based capsuloretinacular flap by sharp dissection off the ulnar neck proximally and off the dorsal part of the triangular fibrocartilage complex (TFCC) distally. Osteotomy of the distal ulna corresponding to the preoperatively planned size of the prosthesis and removal of the ulnar head, while preserving the attachment of the TFCC within the capsuloretinacular flap. Reaming of the ulnar medullary canal. Insertion of a trial prosthesis. The trial prosthesis has to fit accurately into the shaft with a fluoroscopically documented ulna minus situation of minus 1-2 mm at the wrist joint level. After implanting the definite stem and ulnar head of the Herbert ulnar head prothesis (Martin Medizintechnik®, Tuttlingen, Germany), the capsuloretinacular flap is reattached to the dorsal rim of the sigmoid notch through drilling holes and under advanced tension. In patients with an unstable distal ulnar stump, the operative procedure is technically more demanding as it is more difficult to raise a sufficient capsuloretinacular flap and due to the loss of the ulnar head as an anatomic landmark. Long arm cast with 70° elbow flexion, 40° forearm supination, and 20° wrist extension for 2 weeks. Subsequently forearm rotation is limited at 40° in a removable ulnar gutter splint. Six weeks postoperatively unlimited active range of motion is allowed and normal activities are gradually commenced. Return to maximum stress 12 weeks postoperatively. Patient satisfaction is high due to an increased forearm rotation, stronger grip force, and remarkable pain relief. In most patients with an unstable distal ulnar stump following resection arthroplasty of the DRUJ, stability can be restored.

Choosing the Optimum Swab for Canal Drying in Cemented Total Hip Replacement

During total hip replacement, the reamed medullary canal of the femur should represent a clean, dry surface. We compared the effectiveness of 4 different cotton swabs in a synthetic femur that had been reamed to receive a size 1 Exeter trial prosthesis. Swab sizes included a 2.5 cm and a 7.5 cm diameter ribbon gauze, a pair of 10 x 7.5 cms square swabs and a larger surgical packing swab (20 x 22 cms). The ability of the swabs to pack the femur was assessed using both plain radiographs and colour photography (after femoral section). After retrieval from the canal, the total dry weight of the cotton inserted was recorded as was the time required to withdraw each swab type. Only the narrowest (2.5 cm diameter) ribbon gauze was found to achieve comprehensive packing as far as the cement restrictor but it required a longer time for removal, and there may be a case for using larger ribbon gauze in larger femora. The mass of cotton delivered to the canal using small square swabs was half of that delivered using narrow ribbon gauze.

Femoral component placement changes soft tissue balance in posterior-stabilized total knee arthroplasty

Background We developed a new tensor for total knee arthroplasty enabling the soft tissue balance measurement after femoral trial placement with the patello-femoral joint reduced. The purpose of the present study is to compare the measurements of joint gap and ligament balance between osteotomized femoral and tibial surfaces in posterior-stabilized total knee arthroplasty with that between surfaces of femoral trial component and tibial osteotomy. Methods Using this tensor, the effect of femoral trial placement on the soft tissue balance was analyzed in 80 posterior-stabilized total knee arthroplasties for varus osteoarthritic knees. Both joint gap and varus ligament imbalance were measured with 40 lb of joint distraction force at extension and flexion, and compared between before and after femoral trial placement. Findings In assessing the joint gap, there was significant decrease as much as 5.3 mm at extension, not flexion, after femoral trial prosthesis placement. Varus ligament imbalances were significantly reduced with 3.1° at extension and increased with 1.2° in average at flexion after femoral trial placement. Interpretation These changes at extension were caused by tensed posterior structures of the knee with the posterior condyle of the externally rotated aligned femoral trial. At the knee flexion, medial tension in the extensor mechanisms might be increased after femoral trial placement with patello-femoral joint repaired, and increased varus imbalance. Accordingly, we conclude that intensive medial release before femoral component placement to obtain rectangular joint gap depending on the conventional osteotomy gap measurement has a possible risk of medial looseness after total knee arthroplasty.

Behandlung der komplexen intraartikulären Fraktur des distalen Humerus mittels Latitude-Ellenbogenprothese

Therapy of comminuted intraarticular distal humerus fractures in elderly patients with primary total elbow arthroplasty to achieve stable and painless function. Use of "third-generation" elbow prosthesis with the following options:--linked total elbow arthroplasty,--unlinked total elbow arthroplasty,--either with or without radial head replacement,--hemiarthroplasty. Comminuted intraarticular distal humerus fractures with poor bone quality, in which stable osteosynthesis is impossible. Failure of internal fixation without the technical possibility of revision osteosynthesis. Posttraumatic osteoarthritis or rheumatoid arthritis. Open fractures (Gustilo-Anderson type II or III) or contaminated wounds should not initially be treated with total elbow arthroplasty. Prosthetic replacement may be considered after consolidation of the soft tissue. Low compliance, high functional demands. Paralysis of the biceps muscle. Supine positioning of the patient. Surgical approach after Bryan-Morrey. Anterior transposition of the ulnar nerve. Preparation of the insertion of the triceps at the distal humerus, capsule and proximal ulna. Reflection of the triceps in continuity with the ulnar periosteum and the forearm fascia. Attempt at reconstruction of the epicondyles to achieve ligamentary stability and to implant an unlinked prosthesis. If this is technically not possible, the prosthesis is linked at the end of the operation. Removal of the distal humerus fragments. Determination of the prosthesis size. Detection of the extension-flexion axis. Opening of the humeral intramedullary canal. Determination of the offset. Preparation of the humeral prosthesis repository. Placement of the trial prosthesis. Potential implantation of a hemiprosthesis, if radial head, proximal ulna and ligaments are unaffected. Otherwise preparation of the ulnar prosthesis repository. If the radial head is unaffected, it can be preserved. Otherwise it has to be resected and preferably replaced. Placement of the ulnar and radial trial prosthesis. After correct trial reposition cementing of all definitive prosthesis components with attachment of a cortical bone graft behind the ventral flange of the humeral component. If there is no sufficient stability at the end of the operation, the prosthesis must be linked by insertion of the ulnar cap. Postoperative anterior upper-arm splint in full extension. Active motion. No active extension for 6 weeks. Avoidance of single-event weight lifting>5 kg, no repetitive weight lifting>1 kg, and no forced elbow movements, e.g., racquet sports. 15 Latitude elbow prostheses were implanted in 2007 and 2008 at the Department of Trauma Surgery of the University Hospital Mainz, Germany, due to the following indications: fractures (n=7), pseudarthrosis (n=4), posttraumatic osteoarthritis (n=3), and rheumatoid arthritis (n=1). Six hemiprostheses, two unlinked and seven linked prostheses were implanted. The mean age of patients was 67 years (31-88 years). For the treatment of acute fractures, the indication was made only in elderly patients. The mean age was 77 years (66-88 years). Eleven of these 15 patients were reexamined after 13.5 months (6-23 months). The mean extension deficit was 15 degrees (0-30 degrees), the mean flexion 119 degrees (95-140 degrees). The mean pronation was 78 degrees (60-90 degrees), the mean supination 79 degrees (50-90 degrees). According to the Mayo Elbow Performance Score, three patients achieved an excellent, seven a good, and one a fair result. The mean Mayo Score was 89.2 (74-100). The mean DASH (Disabilities of the Arm, Shoulder and Hand) Score was 8.4 (0-28).

Computer-assisted total knee arthroplasty: Does the tibial component remain at malposition risk?

The development of computer-assisted surgery in total knee arthroplasty continues its search for better accuracy in the spatial positioning of prosthetic components and in achieving the best ideal ligament balance. Many studies have underscored the value of computer-assisted navigation in obtaining precise bone cuts in terms of both orientation and location, which would optimize bone resection and thereby fulfill ligament balancing requirements. Yet improving bone cut accuracy can be undermined by positioning errors of the component at the final stage of implantation. The objective of this prospective study was to assess this possible loss of accuracy and to suggest possible solutions to minimize this risk. A consecutive series of 50 total knee arthroplasties was studied using an imageless computer navigation system. This study compared the spatial orientation of the prosthesis components determined using software (frontal positioning for the femoral component, frontal and sagittal positioning for the tibial component) with the recorded orientation of the corresponding bone cuts, which allowed us to quantify the loss of accuracy of these predefined positions after cutting. Trial and final implant orientation was taken into account. Moreover, the mechanical axes of the lower limb, the trial and then the final prosthesis in place were compared. Two procedures were abandoned in the study and two patient files were incomplete, which left a series of 46 cases (29 females and 17 males; mean age at surgery, 67 years; mean BMI, 31.27). Bone cut orientation was consistently found to be satisfactory. Frontal orientation of the final femoral component (0.2° valgus) did not differ statistically significantly from the distal femoral cut (0.3° valgus) and from the orientation of the trial femoral component, as was true of the slope of the tibial component (4.8°) versus the tibial cut (6.3°) and the mechanical axis of the lower limb with the trial prosthesis and the final implant. The frontal plane orientation of the tibial component (0.6° varus) differed statistically significantly from the bone cut (0.1° valgus). Several studies have demonstrated the value of computer-assisted surgery, notably in the accuracy of the bone cuts, confirming the work reported herein. The loss of accuracy observed between the bone cut and the final implantation can only be explained by soft tissues between the prosthesis and the bone cut, unequal cement thickness, an orientation error in the impaction handle when placing the final implant, or a conflict between the prosthetic keel and cortical bone. Better exposure of the tibial plateaus, discontinuation of cement use, and navigated impaction ancillary tools could reduce these errors. Level IV. Prospective study.