Intrinsic constraint of unlinked total elbow replacements--the ulnotrochlear joint

Surgical management of osteoarthritis in the shoulder and elbow

Interesting recent trends are apparent in the setting of shoulder and elbow pathology. There is an increase in utilization of shoulder arthroplasty for osteoarthritis and post traumatic arthritis. At the same time, there remain limited options for osteoarthritis of the elbow particularly in the young and or active patient. This manuscript details surgical options for osteoarthritis at the elbow and shoulder.

Distal Humeral Trochlear Geometry Associated With the Spatial Variation of the Dynamic Elbow Flexion Axis

Background: The complexity of the spatial dynamic flexion axis (DFA) of the elbow joint makes the elbow prosthesis design and humeral component alignment challenging. This study aimed to 1) investigate the variations of the spatial DFA during elbow flexion and 2) investigate the relationship between the distal humeral trochlear geometry and the in vivo spatial variation of the DFA.

Methods: Ten healthy subjects participated in this study. Each subject performed a full elbow extension to maximum flexion with hand supination under dual fluoroscopic imaging system (DFIS) surveillance. The 2D fluoroscopic images and the 3D bone models were registered to analyze the in vivo elbow kinematics and DFAs. The spatial DFA positions were defined as inclination with the medial and lateral epicondyle axes (MLA) in the transverse and coronal planes. The range of the DFA positions was also investigated during different flexion phases. The Spearman correlation method was used to analyze the relationship between the distal humeral trochlear’s morphological parameters and the position of DFAs during different flexion phases.

Results: The pathway of the DFAs showed an irregular pattern and presented individual features. The medial trochlear depth (MTD) (r = 0.68, p = 0.03) was positively correlated with the range of the DFA position (2.8° ± 1.9°) in the coronal plane from full extension to 30° of flexion. Lateral trochlear height (LTH) (r = −0.64, p = 0.04) was negatively correlated with the DFA position (−1.4° ± 3.3°) in the transverse plane from 30° to 60° of flexion. A significant correlation was found between LTH with the DFA position in the coronal (r = −0.77, p = 0.01) and transverse planes (r = −0.76, p = 0.01) from 60° to 90° of flexion.

Conclusion: This study showed that the pathway of the dynamic flexion axis has an individual pattern. The medial and lateral trochlear sizes were the key parameters that might affect the elbow joint flexion function. When recovering complex distal humeral fractures or considering the implant design of total elbow arthroplasty, surgeons should pay more attention to the medial and lateral trochlea’s geometry, which may help restore normal elbow kinematics.

Management of rheumatoid arthritis of the elbow with a convertible total elbow arthroplasty

BACKGROUND

Total elbow arthroplasty (TEA) is commonly performed in patients with rheumatoid arthritis (RA). The purpose of this study was to compare outcomes and complications of unlinked and linked TEA using a convertible system in patients with RA.

METHODS

All patients with RA who underwent TEA at a single center with a minimum of 2 years' follow-up were reviewed. Demographic information, patient-reported outcome scores, functional outcome assessments, and radiographic parameters were evaluated at most recent follow-up.

RESULTS

We evaluated 82 patients (27 with unlinked TEA and 55 with linked TEA) with RA. The mean age at surgery was 61 ± 10 years, with a mean follow-up period of 6 ± 4 years. Demographic characteristics were similar between groups, with the exception of longer follow-up in the unlinked group (8 years vs. 5 years, P = .001). No differences in range of motion were noted. Elbow strength was similar other than pronation strength (74% ± 8% for unlinked vs. 100% ± 8% for linked, P = .03). The mean Mayo Elbow Performance Index was 83 ± 16; Patient Rated Elbow Evaluation score, 15 ± 18; and QuickDASH (short version of the Disabilities of the Arm, Shoulder and Hand questionnaire) score, 34 ± 20. No differences in the rates of reoperation (17% vs. 24%, P = .4), complications (32% vs. 31%, P = .4), or revisions (13% vs. 17%, P = .3) were found between unlinked and linked devices. Four patients with instability, all with unlinked designs, underwent revision to a linked design. Four patients, all with linked designs, underwent revision for aseptic loosening of smooth short-stem ulnar components.

CONCLUSION

TEA using a convertible implant design provides good patient-reported outcomes at mid-term follow-up in patients with RA. Our study was unable to detect a difference in the use of either unlinked or linked implant designs; further large comparison trials are needed.

The effect of implant linking and ligament integrity on humeral loading of a convertible total elbow arthroplasty

BACKGROUND

Both unlinked and linked total elbow arthroplasty (TEA) implants have been employed with no consensus as to the optimal design. The present study aimed to evaluate the effect of collateral ligament integrity and implant linkage on wear-inducing loads in a convertible TEA.

METHODS

Eight fresh frozen upper extremities were tested in an elbow motion simulator. A convertible TEA with an instrumented humeral stem was inserted using computer navigation. Elbow kinematics and humeral loading were recorded with the TEA both linked and unlinked. The collateral ligaments were then sectioned and testing was repeated.

RESULTS

In the dependent position, there was no effect of implant linkage or ligament sectioning on humeral loading. Humeral loading was significantly greater following sectioning of the collateral ligaments but not after linking the TEA with the arm in the valgus position. Humeral loading was significantly greater after linking the TEA but not after sectioning of the collateral ligaments and with the arm in the varus position.

CONCLUSIONS

Collateral ligament integrity reduces wear-inducing loads for both an unlinked and linked TEA. Linkage of a convertible TEA increases humeral loading, which may have detrimental effects on implant longevity.

Macroscopic investigation of failed Kudo type 5 total elbow arthroplasty

BACKGROUND

On the basis of the intra-articular findings during Kudo type 5 elbow prosthesis revision surgery, we infer the mechanisms leading to implant failure.

MATERIALS AND METHODS

We performed primary Kudo type 5 total elbow arthroplasty on 60 rheumatoid elbows in 45 patients between 1994 and 2003. Revision surgery was performed in 8 patients (9 elbows) because of implant failure. We radiographically assessed their status before this surgical procedure and then assessed the surgical intra-articular findings based on surgery records and photographs.

RESULTS

In all cases, revision surgery was necessitated by failure of the ulnar component. There were 2 types of implant failure: fracture of the ulnar component neck (n = 3) and loosening of the ulnar component (n = 6). In the latter group, 2 elbows exhibited valgus deformity of the retrieved ulnar component. There were no cases of metallosis or wear of the articular surface.

CONCLUSION

This study describes the types of implant failure in unlinked Kudo type 5 total elbow arthroplasties with all-polyethylene ulnar components based on the intra-articular findings. Failure of the all-polyethylene ulnar component could have been caused by ulnar neck distortion that occurred prior to polyethylene wear on the joint surface. In addition, valgus stress on the elbow joint may have contributed to these implant failures.

The challenging surgical treatment of closed distal humerus fractures in elderly and octogenarian patients: radiographic and functional outcomes with a minimum follow-up of 24 months

INTRODUCTION

The main purpose of this retrospective, non-randomized, case series study was to evaluate the clinical and radiographic outcomes of distal humerus fractures (DHFs) in a consecutive series of elderly patients operatively treated by two surgeons, and second, to identify proper indications for two elderly age ranges and two fracture pattern groups.

MATERIALS AND METHODS

From January 2009 to June 2014, 51 patients (pts) underwent open reduction and internal fixation (ORIF) using the locking compression plate (LCP) distal humerus plate (DHP) system at our institution. Medical records and radiographs were retrospectively assessed. Patients were divided into 3 groups according to gender, age (pts <85 years, pts ≥85 years) and AO classification (13-B1-B2-C1-C2 or 13-C3). All subjects completed MEPS, Quick-DASH and SF-36 PCS/MCS scores at final follow-up, and statistical analysis was performed.

RESULTS

36 patients (20 women, 16 men), mean age 80.3 years, with AO type 13-B and 13-C DHFs were included with a mean follow-up of 56 months (range 24-92). The most common mechanism of trauma was a fall from ground level (55.6%). The mean MEPS was 78.9 points, Quick-DASH 28.4, SF-36 PCS 48.3 and MCS 48.9. There was statistically significant evidence that having a 13-C3 fracture leads to worse results in MEPS, Quick-DASH and SF-36. The female gender correlates with worse results in SF-36. The patients ≥85 years had a worse prognosis according to Quick-DASH and SF-36, while the AO 13-C3 pattern obtained the worst ROM outcomes versus AO 13 B1-B2-C1-C2 (normal ROM 0°-140°): mean ROM 24°-114° vs 10°-130°, mean flexion deficit 26° vs 10°, mean extension deficit 24° vs 10°, respectively). Complications were presents in 36.1% of patients, overall belonging to the AO type 13-C fracture pattern and to the group ≥85 years.

CONCLUSION

These study data seem to confirm our hypothesis that plate fixation for DHFs guarantees adequate fracture osteosynthesis and satisfactory functional outcomes at medium to long-term follow-up, not only in elderly patients, but also in octogenarian osteoporotic patients (≥85 years) with 13-C1 and 13-C2 fracture patterns, while an alternative solution should be considered for type C3 fractures, even in a primary trauma setting.

The History and Future of Unlinked Total Elbow Arthroplasty

Unlinked total elbow arthroplasty (TEA), which has no mechanical connection between the humeral and ulnar components, has theoretical advantages based on its near-normal elbow kinematics and the preservation of bone stock. Unlinked TEA is appropriate only for patients who have limited bone loss or limited deformity and good ligamentous function. This is because postoperative instability has been a major complication of unlinked prostheses. The concept and goal of unlinked TEA is to share the loading stress on the bone implant interface with the surrounding tissues. Although the loosening rate of unlinked prostheses theoretically should be lower than that of linked prostheses (which have a mechanical connection between the humeral and ulnar components), there is no clear evidence that unlinked TEAs are superior to linked TEAs in this respect. However, we believe that primary TEA should be performed using an unlinked TEA, especially for younger patients, because revision surgery for unlinked TEA results in longer prosthesis survival than revision surgery for linked TEA. Improvement of the design of unlinked prostheses and the introduction of less invasive surgical techniques are required to reduce postoperative instability.

Current concepts in elbow arthroplasty

Distal humeral replacement and the total elbow are two commonly-used arthroplasties

Each prosthesis has evolving indications and surgical techniques

Recent changes in device design and implantation methods are due to biomechanical and clinical outcome-based research

New prostheses and methods provide: better elbow kinematics, more durable bearings and longer-lasting joint replacement potential

Cite this article: EFORT Open Rev 2017;2:83-88. DOI: 10.1302/2058-5241.2.160064

Radial head, radiocapitellar and total elbow arthroplasties: a review of recent literature

The outcome of prosthetic elbow surgery is continually evolving. We thoroughly reviewed the literature on this issue to analyse the indications, outcomes and complications of the numerous types of implants currently in use. Radial head replacement is recommended in comminuted fractures of the radial head and in post-traumatic conditions. Medium- and long-term results prove to be satisfactory in the majority of cases, with no evidence to indicate that some prostheses (monopolar vs. bipolar; cemented vs. press-fit) are more effective than others; nonetheless, the bipolar-cemented implant was found to be associated with a lower revision rate than other prostheses. Unicompartmental arthroplasty has recently been used for the treatment of osteoarthritis and rheumatoid arthritis when the lateral compartment is prevalently involved; the results reported to date have been encouraging, although further studies are warranted to confirm the validity of these implants. Total elbow arthroplasty is performed in a range of conditions, including distal humerus fractures in the elderly and elbow arthritis. In the former condition, linked elbow replacement yields excellent results with few complications and a low revision rate. In elbow arthritis, total elbow arthroplasty is indicated when patients suffer from disabling pain, stiffness and/or instability that prevent them from performing daily activities. Unlinked elbow arthroplasty, which is used above all in rheumatoid arthritis, also yields satisfactory results, although the risk of instability persists. The use of linked elbow arthroplasty, which yields similar results but lower revision rates, has consequently increased. Lastly, the results yielded by linked elbow prosthesis in post-traumatic conditions are good, although not quite as good as those obtained in rheumatoid arthritis. Early mechanical failure may occur in younger and more active patients after elbow arthroplasty. However, the careful selection of patients who are prepared to accept functional limitations imposed by elbow implants will enable indications for elbow arthroplasty to be extended to young subjects, particularly when no other therapeutic options are available.

Linking of total elbow prosthesis during surgery; a biomechanical analysis

BACKGROUND

Presently, 2 types of elbow prostheses are used: unlinked and linked. The Latitude total elbow prosthesis allows the surgeon to decide during the implantation whether the prosthesis is placed unlinked or linked, and whether the native radial head is retained, resected, or replaced. The purpose of this study is to assess and to compare the varus and valgus laxity of the unlinked and linked version of the latitude total elbow prosthesis with: (1) the native radial head preserved, (2) the native radial head excised, and (3) the native radial head replaced by a radial head component.

METHODS

Biomechanical testing was performed on 14 fresh-frozen upper limb specimens.

RESULTS

Linking the prosthesis predominantly influences the valgus laxity of the elbow.

DISCUSSION/CONCLUSION

Linking the Latitude total elbow prosthesis results in increased valgus stability. In the linked version of the total elbow prosthesis, the radial head only plays a small part in both valgus and varus stability. An unlinked situation is not advised in absence of a native radial head or in case of inability to replace the radial head.

Stability of the unlinked Latitude total elbow prosthesis: a biomechanical in vitro analysis

BACKGROUND

The purpose of this study is to assess the valgus and varus laxity of the unlinked version of the Latitude total elbow prosthesis and the effects of radial head preservation or replacement.

METHODS

Biomechanical analysis of the valgus and varus laxity of the unlinked Latitude was performed in fourteen upper limb specimens in the following conditions: (1) native elbow, (2) native elbow after the surgical approach and closing all layers again, (3) elbow with humeral and ulnar component implanted, unlinked, with the native radial head preserved, (4) elbow with humeral and ulnar component implanted, unlinked, with the native radial excised, (5) elbow with humeral, ulnar, and radial head component implanted.

FINDINGS

After implantation of the Latitude total elbow prosthesis both the valgus and varus laxity slightly increase from mid to maximal flexion when compared to the native elbow after surgical approach. The unlinked Latitude total elbow prosthesis provides both valgus and varus stability in elbows with intact ligamentous constraints. With intact ligamentous constraints the radial head component only slightly contributes to the stability of the elbow after implantation of the unlinked Latitude total elbow prosthesis.

INTERPRETATION

The unlinked Latitude total elbow prosthesis provides both valgus and varus stability in elbows with intact ligamentous constraints. The radial head component contributes only slightly to the stability.

Comparison of short- to medium-term results of Coonrad-Morrey elbow replacement in patients with rheumatoid arthritis versus patients after elbow injuries

BACKGROUND

The aim of this study was to assess the utility of the Coonrad-Morrey elbow prosthesis in patients with severe elbow dysfunction secondary to rheumatoid arthritis (RA) or post-traumatic elbow dysfunction.

MATERIAL/METHODS

The study involved 35 patients followed up for a mean of 36 months. The patients were divided into those with RA (Group I) and those with post-traumatic elbow dysfunction (Group II). Treatment outcomes were evaluated according to the Mayo Elbow Performance Score (MEPS) and the Disabilities of the Arm, Shoulder and Hand Score (Quick DASH).

RESULTS

According to the MEPS, there were 20 (57.15%) excellent, 12 (34.3%) good, 1 (2.85%) fair, and 2 (5.7%) poor outcomes. The mean post-operative Quick-DASH score for the entire study group was 37.73 points. In subgroup analysis, the MEPS-based evaluation revealed: 14 (70%) excellent, 5 (25%) good, and 1 (5%) satisfactory outcome in Group I, versus 6 (40%) excellent, 7 (46.7%) good, and 2 (13.3%) poor outcomes in Group II. The mean Quick Dash scores were 78.64 points in Group I and 76.36 points in Group II. The final MEPS scores in Group I (p=0.000018) and Group II (p=0.00065) were most markedly influenced by reduction in elbow pain and improvement in the ability to perform activities of daily living (ADL): p=0.000018 in Group I and p=0.000713 in Group II.

CONCLUSIONS

The treatment outcomes confirm the utility of arthroplasty for severe elbow dysfunctions; they were most strongly influenced by pain reduction and improved ability to perform activities of daily living.

Current concepts of elbow-joint disorders and their treatment

BACKGROUND

Recently, many studies have emphasized the importance of the comprehension of detailed functional anatomy and biomechanics of the elbow and its significant contribution in facilitating good functional outcomes of conservative and surgical treatment in the field of elbow disorders.

METHODS

The most common disease of elbow disorders and their treatment was reviewed.

RESULTS

Lateral epicondylitis of the elbow, is defined as a microscopic tear of extensor carpi radialis brevis tendon, and microscopic findings show immature reparative tissue (angiofibroblastic hyperplasia). The patient needs coordinated rehabilitation, range-of motion-exercise, stretching, and bracing in the second phase. Ninety-five percent of patients with lateral epicondylitis heal spontaneously or conservatively. The medial collateral ligament injury of the elbow is most common in the overhead-throwing athlete. Jobe's procedure, the original reconstruction technique, and its modifications in bone-tunnel creation, allow a tendon graft to be wound in a figure-eight configuration through the tunnels. Further modification of Jobe's procedure in bone-tunnel configuration reduced the total number of tunnels and facilitates easier graft tensioning. Outcomes with these reconstruction techniques have proven effective in returning high-level throwing athletes back to their sport. Arthroscopic surgery for the elbow in the throwing athlete has evolved and has proven successful results. Arthroscopic treatment includes debridement of posteromedial synovitis, loose-body removal, and excision of the olecranon spur. Posteromedial elbow impingement is also a source of disability in the overhead-throwing athlete. Twenty-five percent of these patients require a medial collateral ligament reconstruction after removal of a posteromedial bony spur. Linked and unlinked total elbow arthroplasty are successful treatment procedures for patients with rheumatoid arthritis, posttraumatic osteoarthritis, and elderly patients with comminuted distal humeral fractures and the salvage of distal humeral nonunion. Proper selection and implantation of prostheses are also important to achieve good functional outcome and longevity.

CONCLUSION

The success of treatment of elbow disorders depends greatly on surgical design and technique, both of which require comprehensive knowledge of detailed anatomy and biomechanics of the elbow.

The effect of implant design of linked total elbow arthroplasty on stability and stress: a finite element analysis

Several linked total elbow arthroplasty designs exist, which function similar to a loose hinge joint. Constraint behaviour is an important design consideration, as it affects joint stability, or how much secondary [e.g. varus-valgus (VV)] motion is permitted. Implant durability is also a concern, as bearing failures have been reported. This finite element analysis investigates the constraint characteristics and ultra high molecular weight polyethylene bearing stresses of three linked elbow design concepts [cylindrical (CY), hourglass (HG) and concave cylinder (CC)]. The bearing of the CY design was subjected to elevated Von Mises stresses (2.1-5.4 times higher than the HG and CC designs) due to edge loading. The HG design maintained low stresses, but was unable to provide consistent VV stability. The CC design also maintained low stresses while providing consistent VV stability. These results suggest that CC designs may provide better stability characteristics and durability in vivo, compared to the other two designs.

The Kudo humeral component as primary hemiarthroplasty in distal humeral fractures

BACKGROUND

Treatment of intra-articular fractures of the distal humerus in the elderly is challenging. In patients with very distal fractures and severe comminution, primary arthroplasty has been advocated. Recently, a few reports have described promising results of hemiarthroplasty. This study describes the medium-term results of using the Kudo humeral implant (Biomet Ltd, Bridgend, U.K.) as replacement of the distal humerus.

MATERIAL AND METHODS

Eight women (mean age, 79 years) were treated. Follow-up was conducted at a mean of 4 years after the procedure and consisted of the Mayo Elbow Performance Score (MEPS), radiographic images, and range of motion (ROM).

RESULTS

All patients had a good or excellent outcome according to the MEPS. Mean ROM was 31° to 126°. Radiographic signs of attrition of the ulna were observed in 3 patients but did not correlate with the functional outcome. A periprosthetic fracture occurred in 1 patient 3 years after the index operation, and ROM was unsatisfactory in 1 patient. No other complications were observed.

CONCLUSION

The use of the Kudo humeral implant as a hemiarthroplasty resulted in a reasonable functional outcome in the medium-term, but the radiographic signs of attrition suggest that the implant is not recommended as a hemiprosthesis.

Long-term effectiveness of Sorbie-QUESTOR elbow arthroplasty: single surgeon's series of 15 years

With increasing usage of many types of total elbow replacements, there is a continuing need for clinical series that report survivorship, complications and revisions, and performance of single types of implants over extended time periods. The purpose of this study was to assess the long-term effectiveness of all implants of the Sorbie-QUESTOR (SQ) unlinked surface arthroplasty conducted by a single surgeon (C.S.) over 15 years at a single site, and to determine whether there were diagnostic group differences. Between 1995 and 2002, 51 S-Q prosthetic elbows were implanted into 44 patients. The patient groups were hemophilia, rheumatoid arthritis, and "other," which included osteoarthritis, traumatic arthritis, psoriatic arthritis, and reactive arthritis. Annual evaluations included scores of pain, range of motion, and function. The most recent annual evaluation was included in the data set. Details of complications and revisions were recorded. The hemophiliac group had the best survival outcomes at 87.5%. Eighteen prostheses required revision or removal with all but 3 retained or replaced. Postoperatively, 73% rated their pain as 'slight' or 'none'. The hemophilia and rheumatoid arthritis groups made very large total flexion/extension gains. The rheumatoid arthritis group made significant forearm motion gains. Average functional assessment gains were nearly 2 grades of 5 functional levels and were significant for all groups. The S-Q surface arthroplasty has demonstrated long-term effectiveness in patients with a variety of elbow joint pathologies showing reduction in pain, large gains in joint range and function, and good long-term survival.

Unlinked and convertible total elbow arthroplasty

Total elbow arthroplasty (TEA) is still in its infancy if we compare it with other arthroplasties such as knee or hip. TEA designs have been evolving with experience; however, long-term outcome data remain limited. The designs of total elbow prostheses can be subdivided into 3 general categories: unlinked, linked, and convertible devices. This article focuses on unlinked and convertible prostheses.

Long-term survival of the Souter-Strathclyde total elbow replacement in patients with rheumatoid arthritis

Between 1982 and 1997, 403 consecutive patients (522 elbows) with rheumatoid arthritis underwent Souter-Strathclyde total elbow replacement. By the end of 2007, there had been 66 revisions for aseptic loosening in 60 patients. The mean time of follow-up was 10.6 years (0 to 25) The survival rates at five-, ten, 15 and 19 years were 96% (95%, confidence interval (CI) 95 to 98), 89% (95% CI 86 to 92), 83% (95% CI 78 to 87), and 77% (95% CI 69 to 85), respectively. The small and medium-sized short-stemmed primary humeral components had a 5.6-fold and 3.6-fold risk of revision for aseptic loosening respectively, compared to the medium-sized long-stemmed component. The small and medium-sized all-polyethylene ulnar components had respectively a 28.2-fold and 8.4-fold risk of revision for aseptic loosening, compared to the metal-backed ulnar components.

The use of retentive ulnar components was not associated with an increased risk of aseptic loosening compared to non-retentive implants.

In vivo three-dimensional kinematics of total elbow arthroplasty using fluoroscopic imaging

Higher complication rates and lower survivorship are still seen for total elbow arthroplasties compared to total knee and hip arthroplasties. This is partly due to polyethylene wear of the articular surface induced by excessive articular contact stress during elbow motion. The aim of this study was to dynamically evaluate in vivo three-dimensional elbow motion after total elbow arthroplasty. Twelve patients (15 elbows) who underwent operation with the Osaka University Model Total Elbow System were analysed using X-ray fluoroscopic imaging and a two-dimensional/three-dimensional registration technique, which could accurately estimate the three-dimensional spatial position of components. Valgus/varus angle and rotation between humeral and ulnar components showed wide variations among patients. Elbows with valgus angle and internal rotation >10 degrees could induce edge-loading of the articular surface. Component alignment, articular configuration, and soft-tissue balance can affect the kinematics of total elbow arthroplasty.

Total elbow arthroplasty in rheumatoid arthritis: a population-based study from the Finnish Arthroplasty Register

BACKGROUND AND PURPOSE

Although total elbow arthroplasty (TEA) is a recognized procedure for the treatment of the painful arthritic elbow, the choice of implant is still obscure. We evaluated the survival of different TEA designs and factors associated with survival using data from a nationwide arthroplasty register.

METHODS

1,457 primary TEAs for rheumatoid elbow destruction were performed during 1982 to 2006 in one hospital specialized in the treatment of rheumatoid arthritis (n = 776) and in 19 other hospitals (n = 681). The mean age of the patients was 59 years and 87% of the TEAs were performed in women. We selected different contemporary TEA designs, each used in more than 40 operations including the Souter-Strathclyde (n = 912), i.B.P./Kudo (n = 218), Coonrad-Morrey (n = 164), and NESimplavit/Norway (n = 63) to assess their individual survival rates. Kaplan-Meier analysis and the Cox regression model were used for survival analysis.

RESULTS

The most frequent reason for revision was aseptic loosening (47%). We found no differences in survival rates between different TEA designs. We did, however, find a 1.5-fold (95% CI: 1.1-2.1) elevated risk of revision in unspecialized hospitals as compared to the one hospital specialized in treatment of rheumatoid arthritis. In the Souter-Strathclyde subgroup, there was a reduced risk of revision (RR 0.6, p = 0.001) in TEAs implanted over 1994-2006 as compared to those implanted earlier (1982-1993). The 10-year survivorship for the whole TEA cohort was 83% (95% CI: 81-86), which agrees with earlier reports.

INTERPRETATION

The influence of implant choice on the survival of TEA is minor compared to hip and knee arthroplasties. Inferior survival rates of the TEAs performed in the unspecialized hospitals demonstrates the importance of proper indications, surgical technique, and postoperative follow-up, and endorses the need for centralization of these operations at specialized units.

Variation in the position of the elbow flexion axis after total joint replacement with three different prostheses

The instantaneous flexion axes in rheumatoid patients treated with a Kudo (Biomet UK Ltd, Swindon, UK), Capitellocondylar (Johnson & Johnson Orthopaedics Inc, Raynham, MA), or GSB III (Zimmer GmbH, Winterthur, Switzerland) elbow prosthesis were calculated using radiostereometric analysis and compared with those previously found in the normal elbow in vivo. Variability in the flexion axis position was greater in the prosthetic elbows than reported for healthy subjects. This was especially evident for the unlinked Kudo prosthesis, with dispersions of the axes up to 84.3 degrees in the frontal and 45.0 degrees in the horizontal plane. Corresponding values for the unlinked Capitellocondylar prosthesis were 19.7 degrees and 20.9 degrees. The linked GSB III prosthesis was the most constrained, with dispersions within 15.4 degrees in the frontal and 4.6 degrees in the horizontal plane. The unlinked elbow prostheses displayed considerable axis dispersion under physiologic conditions. Implant design seems to be able to compensate for this to some extent, as indicated, for example, by the results of the Capitellocondylar prosthesis.

The effect of anatomic landmark selection of the distal humerus on registration accuracy in computer-assisted elbow surgery

Incorrect selection of the flexion-extension axis of the elbow may be an important cause of failure following total elbow arthroplasty. Axis selection can be improved by locating it on a pre-operative image and registering the image to the subject intra-operatively. However, registration is dependent on the availability of anatomic landmarks that may be distorted or absent because of tumors, arthritis, dislocations, or fractures. This study determined the anatomic landmarks required to register surface data accurately to a pre-operative image of the distal humerus. Registration error for landmarks unlikely to be compromised by severe bone loss was 1.1 +/- 0.2 mm in translation and 0.4 +/- 0.1 degrees in rotation. These results suggest that a close alignment of a pre-operative image with intra-operative surface data can be achieved using only a relatively small portion of the distal humerus that is readily available to the surgeon, and unlikely to be compromised, even in the setting of significant articular bone loss.

Primary osteoarthritis of the elbow: current treatment options

In the elbow, as in other joints, primary osteoarthritis is characterized by pain, stiffness, mechanical symptoms, and weakness. But primary osteoarthritis of the elbow is unique in that there is relative preservation of articular cartilage and maintenance of joint space, with hypertrophic osteophyte formation and capsular contracture. Medical treatment and physical therapy may be initiated in the early stages of the disease process. Surgical treatment options include arthroscopic osteocapsular débridement, open ulnohumeral arthroplasty, distraction interposition arthroplasty, and total elbow arthroplasty. The potential for instability and loosening following total elbow arthroplasty in the setting of primary osteoarthritis limits the clinical application of this procedure. This patient population is generally younger than that recommended for total elbow arthroplasty, and their higher functional demands have limited the long-term success of this treatment option. The improvement in arthroscopic débridement techniques is perhaps the greatest advancement in the treatment of osteoarthritis of the elbow in recent years.