Recent advances in unlinked total elbow arthroplasty in Japan.

Background: Total elbow arthroplasty (TEA) is a valuable therapeutic approach for improving function and relieving pain in severely deformed elbow joints. However, TEA is associated with a high incidence of complications. In Japan, the use of unlinked TEA has a long history, with the development of the Kudo prosthesis marking a significant milestone. Subsequently, various unlinked implant designs have been developed. Although favorable long-term clinical results have been reported, complications remain a concern. To further improve the outcome of unlinked TEA, attempts have been made in recent years to develop various surgical approaches and intraoperative support devices. This review focuses on the clinical outcomes and recent advances in unlinked TEA in Japan. Methods: A comprehensive review of clinical results and advancements in unlinked TEA in Japan was conducted. The analysis included trends in the number of TEA, medium-term and long-term results for unlinked TEA, surgical approaches, or preoperative planning techniques. Results: Several implant designs have been developed in Japan. Clinical studies have reported satisfactory long-term outcomes with these implants, but complications, such as infection, fractures, and dislocation, have been observed. In order to enhance the outcomes of unlinked TEA, various triceps-on approaches have been developed as alternatives to the triceps-detaching approach, which compromises the continuity between the triceps tendon and ulna, leading to inevitable complications related to the triceps tendon. Preservation or repair of the surrounding soft tissues is considered critical for preventing postoperative instability due to the absence of a radial head in the current unlinked TEA design. Computed tomography-based 3-dimensional preoperative planning has been pioneered in Japan, demonstrating its effectiveness in predicting implant size and achieving appropriate implant placement. Additionally, augmented reality-assisted surgery is being explored to accurately translate preoperative planning into the surgical procedure. Conclusion: Unlinked TEA for inflammatory arthritis has exhibited promising long-term results in Japan, with ongoing efforts to improve surgical techniques and preoperative planning. Further advancements are anticipated to prevent complications such as dislocation and peri-implant fractures.

Influence of Electrodiagnostic Studies on Surgery for Carpal Tunnel Syndrome: A Retrospective Analysis of Data from a Single Urban Institution.

Background: This study aimed to clarify the influence of preoperative electrodiagnostic (EDX) utilisation and its severity on surgically treated patients with carpal tunnel syndrome (CTS). Methods: This retrospective study analysed the data of patients who underwent CTS surgery at our facility from 2012 to 2022. Data regarding age, sex, affected side, diabetes mellitus, rheumatoid arthritis, haemodialysis and insurance type were collected, along with the following clinical information: utilisation of EDX, steroid injection, number of items of preoperative physical examination and history taking, intervals between symptom onset and the initial visit and between the initial visit and surgery, type of surgical procedure and surgery categorisation (primary or revision). EDX data (EDX severity, interval between EDX and surgery and concomitant nerve lesions) were also investigated. Univariate and multivariate analyses were conducted to assess the influence of EDX utilisation and severity on clinical parameters. Results: Of the 343 hands enrolled in our study, 304 (89%) underwent preoperative EDX assessment. EDX severity was classified as normal, mild, moderate or severe in 6 (2%), 18 (6%), 102 (34%) and 178 hands (58%), respectively. After the univariate and multivariable analyses, more items of preoperative physical examination and history taking were associated with non-EDX utilisation, whereas younger age, female sex and steroid injection were associated with milder EDX. Conclusions: Increased number of items of preoperative physical examination and history taking or steroid injection were independently associated with non-EDX utilisation or milder EDX, respectively, suggesting that when thorough clinical evaluation is conducted, hand surgeons may be less likely to request for EDX before surgery. Moreover, their treatment recommendation may be influenced by EDX severity. Level of Evidence: Level III (Diagnostic).

Press-Fit Hemihamate Arthroplasty for the Proximal Interphalangeal Joint.

Background Chronic proximal interphalangeal joint fracture-dislocations with articular malunion are complex injuries. Hemihamate arthroplasty is an established technique for the management of both acute and chronic cases but is associated with several complications. We present the clinical experience of modified press-fit hemihamate arthroplasty. Description of Technique The base of the middle phalanx was exposed from the volar side, and the cartilage defect of the proximal interphalangeal joint (PIPJ) was evaluated in the hyperextended position. A bone hole was created slightly toward the volar side to recreate the curvature of the PIPJ. The hemihamate osteochondral graft was harvested and fixed into the bone hole in a press-fit manner without using a screw. The volar plate and flexor tendon sheath were then reattached. Patients and Methods The study included three patients with chronic dorsal fracture-dislocations of the PIPJ. All patients were treated for >6 weeks after the injury (average 11 weeks). Results The average total arc of motion of the affected joint improved from 38 degrees before surgery to 80 degrees after surgery. Radiographically, bone union and congruity of the joint surface were achieved in all the patients. None of the treated patients complained of resting pain and reported minimal pain during activity (average visual analog scale 0.5; range 0-1.4). Conclusions Press-fit hemihamate arthroplasty is a safe and effective procedure for treating chronic PIPJ fracture-dislocations without the risk of screw protrusion.

Surgical Approaches for Thoracic Outlet Syndrome: A Review of the Literature.

Thoracic outlet syndrome (TOS) is caused by entrapment of the neurovascular bundle in the interscalene, costoclavicular, or subpectoral minor space. Compression in the interscalene or costoclavicular space with the first rib and scalene muscle leads to vascular and neurogenic TOS, whereas compression in the subpectoral minor space leads to pectoralis minor syndrome. Various surgical approaches exist for the treatment of TOS. The introduction and development of surgical approaches have minimized surgical invasiveness and complications. The reported approaches include transaxillary, supraclavicular, infraclavicular, posterior, combined transaxillary and supraclavicular, combined supraclavicular and infraclavicular (paraclavicular), endoscopic-assisted transaxillary, and video-assisted thoracoscopic approaches. In this review, we summarize the reported surgical approaches for TOS treatment, in terms of the history of the approach, surgical procedure, advantages and disadvantages, clinical outcomes, and complications. An adequate excision of compression structures, including the first rib and scalene muscles, provides satisfactory outcomes regardless of the approach selected, whereas an inadequate release of compression structures leads to failed or recurrent outcomes. Reducing the risk of complications is the most important aspect of TOS management. Surgery should be performed safely, with sufficient resection of compression structures. Additionally, the approach should be selected based on the surgeon's skill, surgeon's preferences, surgical invasiveness, cosmetic appearance, and the presence of special equipment, as well as other advantages and disadvantages of each approach.

Nonunion of the so-called acromion: a systematic review with consideration of the terminology.

INTRODUCTION: There is no widely accepted standard for the classification and treatment of traumatic acromion/scapular spine fracture nonunion due to the scarcity of this condition and the confusion of terminology. MATERIALS AND METHODS: PubMed and Scopus were searched using "scapular fracture" and "acromion fracture" or "scapular spine fracture" as search terms. The inclusion criteria were English full-text articles concerning acromion/scapular spine fracture nonunion that described patient characteristics and presented appropriate images. The exclusion criteria were cases without appropriate images. Citation tracking was conducted to find additional articles and notable full-text articles written in other languages. Fractures were classified using our newly proposed classification system. RESULTS: Twenty-nine patients (19 men, 10 women) with 29 nonunions were identified. There were four type I, 15 type II, and 10 type III fracture nonunions. Only 11 fractures were isolated. The mean period from initial injury to final diagnosis was 35.2 ± 73.2 months (range 3-360 months) (n = 25). The most frequent cause of delayed diagnosis was conservative treatment for fracture in 11 patients, followed by oversight by the physician in 8. The most common reason for seeking medical advice was shoulder pain. Six patients received conservative therapy, and 23 received operative treatment. Fixation materials included various plates in 15 patients, and tension band wiring in 5. Bone grafting was performed in 16 patients (73%, 16/22). Of the 19 surgically treated patients with adequate follow-up, the outcome was rated excellent in 79%. CONCLUSIONS: Isolated acromion/scapular spine fracture nonunion is rare. Fracture type II and III, arising in the anatomical scapular spine, accounted for 86% of the fractures. Computed tomography is required to prevent fracture oversight. Surgical therapy produces good stable results. However, it is important to select the appropriate surgical fixation method and material after considering the anatomical characteristics of the fracture and stress on the fractured portion. LEVEL OF EVIDENCE: V.

Factors Associated with Change in Diagnosis of Carpal Tunnel Syndrome after Electrodiagnostic Studies.

Background: Hand surgeons sometimes place more weight on clinical findings and may not always consider the results of electrodiagnostic studies (EDX) in the diagnosis of carpal tunnel syndrome (CTS). The aim of this study is to determine factors associated with a change in diagnosis of CTS after EDX. Methods: This is a retrospective study of all patients with an initial clinical diagnosis of CTS who underwent EDX at our hospital. We identified patients whose diagnosis changed from CTS to non-CTS after EDX and used univariate and multivariate analysis to determine if age, sex, hand dominance, unilateral symptoms, history of diabetes mellitus, rheumatoid arthritis, haemodialysis, cerebral lesion, cervical lesion, mental disorder, initial diagnosis by a non-hand surgeon, the number of examined items in CTS-6 and a CTS-negative EDX result were associated with a change in diagnosis after EDX. Results: A total of 479 hands with a clinical diagnosis of CTS underwent EDX. The diagnosis was changed to non-CTS in 61 hands (13%) after EDX. Univariate analysis demonstrated that unilateral symptoms, cervical lesion, mental disorder, initial diagnosis by a non-hand surgeon, the number of examined items and a CTS-negative EDX result were significantly associated with a change in diagnosis. In the multivariate analysis, only the number of examined items was significantly associated with a change in diagnosis. Conclusions: EDX results were particularly valued in hands where the initial diagnosis was uncertain for CTS. In hands with an initial diagnosis of CTS, the performance of sufficient history-taking and physical examination was more valued at the final diagnosis than EDX results or other aspects of the patient's background. The process of confirming a clear initial clinical diagnosis of CTS using EDX may be of little value for decision-making at the final diagnosis. Level of Evidence: Level III (Therapeutic).

Distal Radioulnar Joint Locking with Bipolar Injury.

Background Locking of the distal radioulnar joint (DRUJ) induces restriction of the active and passive motion of pronation or supination of the forearm. Diagnosis of DRUJ locking due to a triangular fibrocartilage complex (TFCC) tear is sometimes difficult. Case Description A 15-year-old female suffered from restriction of forearm supination after cast immobilization for the treatment of an elbow injury. The active and passive range of motion (ROM) of supination was 30 degrees, while the active ROM of pronation was normal. Radiographs of the elbow showed a fracture of the medial epicondyle and a fracture around the radial head. Radiographs of the wrist showed a subluxation of the ulnar head. Accurate diagnosis of supination restriction was difficult before surgery, so an operation was performed for the diagnosis and treatment. DRUJ locking was reduced manually and arthroscopic findings showed central perforation of the TFCC. Forearm supination improved to 90 degrees postoperatively. Literature Review DRUJ locking due to a TFCC injury is rare and this condition with bipolar injury has not been reported. Clinical Relevance DRUJ locking due to an injured TFCC should be considered as one of the differential diagnoses of supination contracture.

Endoscopic-assisted Infraclavicular Approach for First-Rib Resection in Neurologic Thoracic Outlet Syndrome: A Report of Two Cases.

Various reported surgical approaches for the treatment of thoracic outlet syndrome (TOS) exist and no firm evidence exists for any approach. A 16-year-old and a 29-year-old male presented with numbness in the upper limb. Neurologic TOS was diagnosed, and surgery was planned for the resection of the first rib and scalene muscles. Through an infraclavicular incision, open resection of the anterior scalene muscle and the anterior aspect of the first rib was performed. With the assistance of endoscopy, the middle scalene muscles and the posterior aspect of the first rib were resected. Preoperative symptoms improved after surgery without any complications. The endoscopic-assisted infraclavicular approach enabled resection of the first rib and scalene muscles, leading to satisfactory outcomes. Level of Evidence: Level V (Therapeutic).

Comparative study on the effectiveness of bone grafting for arthrodesis of the thumb carpometacarpal arthritis.

The aim of this retrospective study was to assess the effectiveness of autogenous bone grafting for arthrodesis of the thumb carpometacarpal joint by comparing the bone union rates with and without bone grafting. We included 36 patients who underwent arthrodesis of the thumb carpometacarpal joint for arthritis (20 patients with bone grafts and 16 without bone grafts). Implants used for internal fixation were K-wire, tension band wiring, headless compression screw and locking plate. The presence of bone union and the time from surgery to bone union were evaluated. The bone union rate was 20/20 (100%) in the bone grafting group and 12/16 (75%) in the non-bone grafting group (p = 0.03). There were no significant differences between the two groups in the time from surgery to bone union and patient characteristics. In conclusion, autogenous bone grafting may contribute to the bone union in the arthrodesis of thumb carpometacarpal arthritis.Level of evidence: III.

A case of neuropathic arthropathy of the elbow with early loosening after total elbow arthroplasty.

We reported the case of a 65-year-old woman who presented with neuropathic arthropathy of the elbow and had undergone cervical spinal cord tumour resection at 32 years of age. Open synovectomy with free-body resection was performed; however, the instability of the elbow joint rapidly progressed. Therefore, we performed total elbow arthroplasty (TEA) using a linked-type prosthesis. However, the humeral stem became severely loosened 1 year after arthroplasty. Furthermore, a periprosthetic humeral fracture developed due to a minor trauma. A revision TEA using a long-stem prosthesis was performed 4 years after the primary TEA. Radiographs taken 2 years after the revision surgery showed no evidence of implant loosening. In this case, early postoperative loosening occurred despite the use of a linked-type prosthesis and an appropriate cementing technique, suggesting that normal implants may not provide sufficient fixation for neuropathic arthropathy of the elbow. Since surgery for neuropathic arthropathy generally has a poor prognosis, surgical interventions including TEA should be carefully considered.

Rupture of the Flexor Pollicis Longus Tendon Involved between the Radial Shaft and the Volar Locking Plate.

We report the case of a 61-year-old woman with right-sided flexor pollicis longus (FPL) tendon ruptured a month after volar locking plate fixation. Five months after the initial operation, hardware removal and reconstruction of the FPL tendon with the ipsilateral palmaris longus were performed. The proximal stump of the ruptured FPL tendon was found in the space between the distal radius and plate.

Painful snapping of the middle finger caused by hyperplasia of the ulnar lateral band: A case report.

Snapping of fingers can be caused by pathologies such as stenosing flexor tenosynovitis. However, snapping symptoms in the metacarpophalangeal (MP) joint caused by hypertension and hyperplasia of the lateral band are rare. We present a 26-year-old female with symptoms of painful snapping of the middle finger. When the finger was actively flexed from the hyperextension of the MP joint, the ulnar lateral band was prominent, and a snapping phenomenon occurred. The cause of the snapping finger was considered to be tightness of the ulnar lateral band, and surgery was planned. Intraoperatively, the ulnar lateral band was tense and hyperplastic. The snapping phenomenon disappeared immediately after the resection of the lateral band. It is important to consider this condition as one of the differential diagnoses of snapping finger when the patient complains of an atypical snapping phenomenon.

Evaluation of Radiographic Changes 5 Years After Arthroscopic Rotator Cuff Repair.

Background: Radiographic changes in the glenohumeral joint often occur after rotator cuff repair; however, the details of the progression and underlying causes remain unknown. Purpose: To retrospectively evaluate the timing and frequency of radiographic changes after arthroscopic rotator cuff repair and to clarify the predictive factors that affect the onset of such changes using multivariate analysis. Study Design: Case-control study; Level of evidence, 3. Methods: We retrospectively reviewed 100 patients with 5 years of follow-up after arthroscopic rotator cuff repair and evaluated the postoperative shift in radiographic findings on plain radiographs every year during follow-up. Factors related to osteoarthritis, acromial spur re-formation, and greater tuberosity resorption at 5 years after surgery were evaluated using logistic regression analyses. Explanatory variables included preoperative factors, intraoperative factors, and postoperative retear. Baseline variables significant in the univariate analyses were included in the multivariate models. Results: Of the 100 patients, 12 developed osteoarthritis, 26 developed acromial spur formation, and 16 developed greater tuberosity resorption at 5 years after surgery. The incidence and grade of osteoarthritis and acromial spur gradually increased over time postoperatively. On the other hand, greater tuberosity resorption developed within 2 years after surgery but did not progress later. Multivariate analysis showed that a larger anteroposterior tear size (odds ratio [OR], 1.09; 95% CI, 1.01-1.17; P = .037) was a risk factor for postoperative osteoarthritis. Early retear (OR, 10.26; 95% CI, 1.03-102.40; P = .047) was a risk factor for acromial spur re-formation. Roughness of the greater tuberosity (OR, 9.07; 95% CI, 1.13-72.82; P = .038) and larger number of suture anchors (OR, 3.34; 95% CI, 1.66-6.74; P = .001) were risk factors for greater tuberosity resorption. Conclusion: Our study showed that radiographic changes occurred in 40% of patients within 5 years after arthroscopic rotator cuff repair. While the osteoarthritic changes and acromial spur re-formation gradually progressed postoperatively, the greater tuberosity resorption stopped within 2 years after surgery. Tear size, morphology of the greater tuberosity, and the number of suture anchors can affect radiographic changes. Furthermore, this study suggested that acromial spur re-formation may be an indicator of early retears.

Arthroscopic Distal Clavicle Resection for an Acromioclavicular Ganglion Cyst with Cuff Tear Arthropathy: A Case Report.

CASE: A 77-year-old man with an acromioclavicular joint ganglion cyst with cuff tear arthropathy had a large mass in the left shoulder. Arthroscopic distal clavicle resection successfully relieved his symptoms without loss of shoulder function by enlargement of the bypass between the cyst and subacromial space through the acromioclavicular joint. CONCLUSION: Arthroscopic distal clavicle resection can remove a 1-way check valve in a minimally invasive manner. This case indicated that arthroscopic distal clavicle resection could be a useful treatment option for patients with acromioclavicular joint ganglion cysts with functional but irreparable rotator cuff tears.

Three-dimensional alignment of the upper extremity in the standing neutral position in healthy subjects.

BACKGROUND: Though alignment of the spine and lower extremities in the standing neutral position has been evaluated, a few studies evaluating the alignment of the upper extremities have also been made. This study assessed the normal alignment of the upper extremities in the standing neutral position and clarified the three-dimensional angular rotations of the upper extremity joints. METHODS: Computed tomography (CT) images of 158 upper extremities from 79 healthy volunteers were prospectively acquired in the standing neutral position using an upright CT scanner. Three-dimensional coordinate systems of the thorax, scapula, humerus, and forearm were designated, and three-dimensional angular rotations of the scapulothoracic, glenohumeral, and elbow joints were calculated. RESULTS: The median angle of the scapulothoracic joint was 9.2° (interquartile range [IQR], 5.2°-12.5°) of upward rotation, 29.0° (IQR, 24.9°-33.3°) of internal rotation, and 7.9° (IQR, 4.3°-11.8°) of anterior tilt. The median angle of the glenohumeral joint was 4.5° (IQR, 0.9°-7.8°) of abduction, 9.0° (IQR, 2.2°-19.0°) of internal rotation, and 0.3° (IQR, - 2.6°-3.1°) of extension. The median angle of the elbow joint was 9.8° (IQR, 6.9°-12.4°) of valgus, 90.2° (IQR, 79.6°-99.4°) of pronation, and 15.5° (IQR, 13.2°-18.1°) of flexion. Correlations in angular rotation values were found between the right and left upper extremities and between joints. CONCLUSIONS: This study clarified the three-dimensional angular rotation of upper extremity joints in the standing neutral position using an upright CT scanner. Our results may provide important insights for the functional evaluation of upper extremity alignment.

Risk Factors for Loss of Active Shoulder Range of Motion in Massive Rotator Cuff Tears.

BACKGROUND: Patients with massive rotator cuff tears often exhibit loss of active range of shoulder motion, which can interfere with activities of daily living. The risk factors for loss of motion remain largely unknown. PURPOSE: To clarify the predictive factors that affect the range of motion in chronic massive rotator cuff tears using multivariate analyses. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: The authors retrospectively reviewed 204 consecutive patients who were evaluated at their institution with chronic massive rotator cuff tears. In this study, the dependent variable was determined to be active anterior elevation limited to ≤90° or external rotation (ER) with the arm at the side limited to ≤0°. Explanatory variables included age; sex; affected side; duration of symptoms; smoking history; existence of diabetes, hypertension, or rheumatoid arthritis; involved tendons; presence of a 3-tendon tear; rupture of the long head of biceps tendon; superior migration of the humeral head; and cuff tear arthropathy. Baseline variables that were observed to be significant in the univariate analyses were included in multivariate models, which used logistic regression to identify independent predictors of loss of motion. RESULTS: Overall, 73 patients (35.8%) exhibited limited anterior elevation, and 27 (13.2%) exhibited limited ER. Multivariate analyses showed that inferior subscapularis tear (odds ratio [OR], 14.66; 95% CI, 2.95-72.93; P = .001), smoking (OR, 4.13; 95% CI, 1.94-8.79; P < .001), superior migration of humeral head (OR, 3.92; 95% CI, 1.80-8.53; P = .001), and 3-tendon tear (OR, 3.29; 95% CI, 1.32-8.20; P = .011) were significantly associated with the loss of anterior elevation. Teres minor tear (OR, 73.37; 95% CI, 9.54-564.28; P < .001) and superior migration of the humeral head (OR, 3.55; 95% CI, 1.04-12.19; P = .044) were significantly associated with loss of ER. CONCLUSION: In the current study, a history of smoking, type of torn tendons, and superior migration of the humeral head were associated with loss of active shoulder motion. In particular, the status of inferior subscapularis or teres minor contributed to the onset of pseudoparalysis in massive rotator cuff tears.

Blocking screw augmentation in intramedullary nailing for displaced surgical neck fractures of the proximal humerus.

A displaced surgical neck fracture can be a good indication for antegrade intramedullary nailing. However, nail insertion may result in malreduction and translational displacement of the humeral head fragment because of muscle traction and size discrepancies between the diameters of the medullary canal and the intramedullary nail. We used blocking screw augmentation in 20 fractures with residual medial displacement of the distal fragment after nail insertion to anatomically reduce displacement of the fracture and to maintain the reduced position before bone union. A blocking screw was placed percutaneously at the lateral side of the canal. Next, a straight intramedullary nail was reinserted medial to the blocking screw. Finally, the nail was locked both proximally and distally. All cases showed bone union without fixation failure at the time of the final follow-up. Blocking screw augmentation with intramedullary nailing is feasible for the treatment of humeral surgical neck fractures and is thought to be helpful for fracture reduction during surgery and stable fixation after surgery.

Aging Aggravates the Progression of Muscle Degeneration After Rotator Cuff Tears in Mice.

PURPOSE: The purpose of this study was to evaluate the impact of aging on muscle degeneration after rotator cuff tear (RCT) in mice. METHODS: Young (12-week-old) and aged (50-to-60-week-old) female C57BL/6 mice were used (n = 29 for each group). The rotator cuff was transected, and the proximal humerus was removed to induce degeneration of the rotator cuff muscles. The mice were euthanized 4 and 12 weeks after the procedure (referred to as RCT-4wk mice and RCT-12wk mice, respectively) and compared with the sham-treated mice. The supraspinatus muscles were collected for histology, Western blot analysis, and gene expression analyses. RESULTS: There was a significant increase in fat tissue in aged RCT-4wk mice (P = .001) and aged RCT-12wk mice (P < .001) compared with sham-treated aged mice, and aged RCT-12wk mice had a significantly increased fat area ratio compared with aged RCT-4wk mice (P < .001). The fat area was significantly larger in both the aged RCT-4wk (P = .002) and RCT-12wk mice (P < .001) than in the corresponding young mice. Muscular fibrosis was significantly increased in aged RCT-12wk mice compared with aged sham-treated mice (P = .005) and young RCT-12wk mice (P = .016). There were also significant increases in the expression of perilipin and transcripts of adipogenic and fibrogenic differentiation markers in aged RCT mice compared with young RCT mice. CONCLUSION: The present results show that aging is critically involved in the pathology of muscular fatty infiltration and fibrosis after RCT, and muscular degeneration progresses over time in aged mice. CLINICAL RELEVANCE: Aging promotes the progression of muscle degeneration in a mouse RCT model. Furthermore, this study shows that muscle degeneration occurs in aged mice even without denervation and that the model described in the present study is a useful tool for studying the pathology of muscle degeneration.

Total elbow arthroplasty using an augmented reality-assisted surgical technique.

BACKGROUND: Precision placement of implants in total elbow arthroplasty (TEA) using conventional surgical techniques can be difficult and riddled with errors. Modern technologies such as augmented reality (AR) and 3-dimensional (3D) printing have already found useful applications in many fields of medicine. We proposed a cutting-edge surgical technique, augmented reality total elbow arthroplasty (ARTEA), that uses AR and 3D printing to provide 3D information for intuitive preoperative planning. The purpose of this study was to evaluate the accuracy of humeral and ulnar component placement using ARTEA. METHODS: Twelve upper extremities from human frozen cadavers were used for experiments performed in this study. We scanned the extremities via computed tomography prior to performing TEA to plan placement sites using computer simulations. The ARTEA technique was used to perform TEA surgery on 6 of the extremities, whereas conventional (non-ARTEA) techniques were used on the other 6 extremities. Computed tomography scanning was repeated after TEA completion, and the error between the planned and actual placements of humeral and ulnar components was calculated and compared. RESULTS: For humeral component placement, the mean positional error ± standard deviation of ARTEA vs. non-ARTEA was 1.4° ± 0.6° vs. 4.4° ± 0.9° in total rotation (P = .002) and 1.5 ± 0.6 mm vs. 8.6 ± 1.3 mm in total translation (P = .002). For ulnar component placement, the mean positional error ± standard deviation of ARTEA vs. non-ARTEA was 5.5° ± 3.1° vs. 19.5° ± 9.8° in total rotation (P = .004) and 1.5 ± 0.4 mm vs. 6.9 ± 1.6 mm in total translation (P = .002). Both rotational accuracy and translational accuracy were greater for joint components replaced using the ARTEA technique compared with the non-ARTEA technique (P < .05). CONCLUSION: Compared with conventional surgical techniques, ARTEA had greater accuracy in prosthetic implant placement when used to perform TEA.