Metallic radial head arthroplasty improves valgus stability of the elbow

The stabilizing influence of radial head arthroplasty was studied in eight medial collateral ligament deficient anatomic specimen elbows. An elbow testing apparatus, which used computer controlled pneumatic actuators to apply tendon loading, was used to simulate active elbow flexion. The motion pathways of the elbow were measured using an electromagnetic tracking device, with the forearm in supination and pronation. As a measure of stability, the maximum varus to valgus laxity over the range of elbow flexion was determined from the difference between varus and valgus gravity loaded motion pathways. After transection of the medial collateral ligament, the radial head was excised and replaced with either a silicone or one of three metallic radial head prostheses. Medial collateral ligament transection caused a significant increase in the maximum varus to valgus laxity to 18.0 degrees +/- 3.2 degrees. After radial head excision, this laxity increased to 35.6 degrees +/- 10.3 degrees. The silicone implant conferred no increase in elbow stability, with a maximum varus to valgus laxity of 32.5 degrees +/- 15.5 degrees. All three metallic implants improved the valgus stability of the medial collateral ligament deficient elbow, providing stability similar to the intact radial head. The use of silicone arthroplasty to replace the radial head in the medial collateral ligament deficient elbow must be questioned. Metallic radial head arthroplasty provides improved valgus stability, approaching that of an intact radial head.     

Kinematics and functional characteristics of the Pritchard ERS unlinked total elbow arthroplasty

This study examined the kinematic characteristics of the Pritchard ERS elbow-resurfacing system, with special attention paid to the effects of the radial head component. The kinematics between the ulna and humerus were assessed in 6 human cadaveric specimens by an electromagnetic tracking system throughout a full flexion/extension range of motion. The elbows were studied under 2 loading conditions, in 3 orientations (neutral, varus, and valgus), and under 4 surgical conditions. The varus/valgus and internal/external rotation laxities were used to assess the condition differences. Specifically, the maximum laxities throughout the extension motion were compared, as were the laxities at 40 degrees, 75 degrees, and 110 degrees of flexion. Both the varus/valgus and internal/external rotation laxities of the ulnohumeral joint increased after total elbow arthroplasty (TEA) implantation, with and without a radial head. This increase was most evident in the extension portion of the arc of motion. At 40 degrees of flexion, the varus/valgus laxity of the intact elbow was 4 degrees +/- 2 degrees versus 11 degrees +/- 8 degrees for a TEA with a radial head and 22 degrees +/- 11 degrees for a TEA without a radial head while the elbow was being subjected to compressive loads via the biceps, brachialis, and triceps. The kinematic data demonstrate a consistent increase in laxity with the Pritchard ERS TEA. They also indicate that a radial head component is necessary for optimal tracking and stability of the ERS arthroplasty.     

Kinematics of semi-constrained total elbow arthroplasty.

We used 11 cadaver elbows and a three-dimensional electromagnetic tracking device to record elbow movements before and after implantation of a 'loose-hinged' elbow prosthesis (modified Coonrad). During simulated active motion there was a maximum of 2.7 degrees (+/- 1.5 degrees) varus/valgus laxity in the cadaver joints. This increased slightly after total elbow arthroplasty to 3.8 degrees (+/- 1.4 degrees). These values are lower than those recorded for the cadaver joints and for the prostheses at the limits of their varus/valgus displacements, indicating that both behave as 'semi-constrained' joints under physiological conditions. They suggest that the muscles absorb some of the forces and moments that in a constrained prosthesis would be transferred to the prosthesis-bone interface.     

Contribution of monoblock and bipolar radial head prostheses to valgus stability of the elbow.

BACKGROUND: The purpose of this study was to evaluate the stabilizing effect of radial head replacement in cadaver elbows with a deficient medial collateral ligament. METHODS: Passive elbow flexion with the forearm in neutral rotation and in 80 degrees of pronation and supination was performed under valgus and varus loads (1) in intact elbows, (2) after a surgical approach (lateral epicondylar osteotomy of the distal part of the humerus), (3) after release of the anterior bundle of the medial collateral ligament, (4) after release of the anterior bundle of the medial collateral ligament and resection of the radial head, and (5) after subsequent replacement of the radial head with each of three different types of radial head prostheses (a Wright monoblock titanium implant, a KPS bipolar Vitallium [cobalt-chromium]-polyethylene implant, and a Judet bipolar Vitallium-polyethylene-Vitallium implant) in the same cadaver elbow. Total valgus elbow laxity was quantified with use of an electromagnetic tracking device. RESULTS: The mean valgus laxity changed significantly (p < 0.001) as a factor of constraint alteration. The greatest laxity was observed after release of the medial collateral ligament together with resection of the radial head (11.1 degrees +/- 5.6 degrees). Less laxity was seen following release of the medial collateral ligament alone (6.8 degrees +/- 3.4 degrees), and the least laxity was seen in the intact state (3.4 degrees +/- 1.6 degrees). Forearm rotation had a significant effect (p = 0.003) on valgus laxity throughout the range of flexion. The laxity was always greater in pronation than it was in neutral rotation or in supination. The mean valgus laxity values for the elbows with a deficient medial collateral ligament and an implant were significantly greater than those for the medial collateral ligament-deficient elbows before radial head resection (p < 0.05). The implants all performed similarly except in neutral forearm rotation, in which the elbow laxity associated with the Judet implant was significantly greater than that associated with the other two implants. CONCLUSIONS AND CLINICAL RELEVANCE: This study showed that a bipolar radial head prosthesis can be as effective as a solid monoblock prosthesis in restoring valgus stability in a medial collateral ligament-deficient elbow. However, none of the prostheses functioned as well as the native radial head, suggesting that open reduction and internal fixation to restore radial head anatomy is preferable to replacement when possible.     

Role of collateral ligaments in the GSB-linked total elbow prosthesis.

The GSB III elbow prosthesis is a loose-hinged type of elbow implant. The introduction of such hinged elbow arthroplasty expanded the indications for elbow replacement to patients with more deficient bone and ligaments. The purpose of this study was to compare the kinematics and stability of the GSB III elbow prosthesis with that of the normal elbow and to investigate the role of the collateral ligaments in the kinematics and the stability of the GSB III total elbow prosthesis in an in vitro model. The results could show a semiconstrained kinematic pattern of the GSB III implant. The mean laxity for varus/valgus stress of the implant without collateral ligament support was significantly greater for all flexion angles when compared with intact elbows (mean, 12.7 degrees versus 5.4 degrees ) and with elbows treated with a standard implantation technique (mean, 9.5 degrees ). The release of the collateral ligaments increased the already observed varus shift after standard implantation of a GSB III elbow prosthesis. The laxity measured without collateral ligaments during loaded movement reached the maximum varus/valgus laxity of the GSB III prosthesis of 12 degrees degrees. The study confirms the role of the collateral ligaments in stabilizing the GSB III elbow prosthesis. Missing collateral ligaments may overload the implant-cement-bone interface and may be one factor contributing to early aseptic loosening of this device.     

Revision of unstable capitellocondylar (unlinked) total elbow replacement

BACKGROUND: Instability is a recognized complication associated with unlinked total elbow implants. The best form of treatment of this problem is uncertain as very little has been written about it. METHODS: Twelve patients underwent operative treatment of instability at the site of a capitellocondylar unlinked total elbow replacement, and the results were reviewed retrospectively. The study group included ten women and two men with an average age of fifty-eight years. Ten patients had rheumatoid arthritis. Three elbows underwent conversion to a semi-constrained hinged prosthesis. In the other nine elbows, an attempt was made to continue with an unlinked prosthesis: three had reconstruction of one or both collateral ligaments, four had component revision, and two had both ligament reconstruction and component revision. RESULTS: After an average duration of follow-up of six years (range, two to fifteen years) only three patients had retained a functioning unlinked prosthesis. Of the remaining nine patients, three had had a conversion to a semi-constrained arthroplasty at the time of the index procedure, four had had a conversion to a semi-constrained prosthesis at the time of a salvage procedure, one had had a resection arthroplasty, and one had a painfully dislocated elbow and had declined revision. Thus, seven elbows eventually underwent conversion to a semi-constrained prosthesis; these conversion procedures were technically difficult, with perforation of the humerus occurring in six patients and perforation of the ulna occurring in four. After all procedures, the average elbow flexion was 132 degrees and the average flexion contracture was 25 degrees. According to the Mayo Elbow Performance Index, there were four excellent results, three good results, three fair results, and one poor result. CONCLUSIONS: Revision of an unlinked total elbow prosthesis to a linked total elbow prosthesis is difficult, but it restores elbow function. Although the present series documents the unpredictability of attempts to salvage an unstable unlinked prosthesis, it seems reasonable to attempt at least one soft-tissue procedure before converting to a linked prosthesis.     

The effect of radial head fracture size on elbow kinematics and stability.

This study determined the effect of radial head fracture size and ligament injury on elbow kinematics. Eight cadaveric upper extremities were studied in an in vitro elbow simulator. Testing was performed with ligaments intact, with the medial collateral (MCL) or lateral collateral (LCL) ligament detached, and with both the MCL and LCL detached. Thirty degree wedges were sequentially removed from the anterolateral radial head up to 120 degrees . Valgus angulation and external rotation of the ulna relative to the humerus were determined for passive motion, active motion, and pivot shift testing with the arm in a vertical (dependent) orientation. Maximum varus-valgus laxity was calculated from measurements of varus and valgus angulation with the arm in horizontal gravity-loaded positions. No effect of increasing radial head fracture size was observed on valgus angulation during passive and active motion in the dependent position. In supination, external rotation increased with increasing fracture size during passive motion with LCL deficiency and both MCL and LCL deficiency. With intact ligaments, maximum varus-valgus laxity increased with increasing radial head fracture size. With ligament disruption, elbows were grossly unstable, and no effect of increasing radial head fracture size occurred. During pivot shift testing, performed with the ligaments intact, subtle instability was noted after resection of one-third of the radial head. In this in vitro biomechanical study, small subtle effects of radial head fracture size on elbow kinematics and stability were seen in both the ligament intact and ligament deficient elbows. These data suggest that fixation of displaced radial head fractures less than or equal to one-third of the articular diameter may have some biomechanical advantages; however, clinical correlation is required.     

Coronoid process and radial head as posterolateral rotatory stabilizers of the elbow

BACKGROUND: The purpose of this study was to evaluate the role of the radial head and the coronoid process as posterolateral rotatory stabilizers of the elbow and to determine the stabilizing effect of radial head replacement and coronoid reconstruction. METHODS: The posterolateral rotatory displacement of the ulna was measured after application of a valgus and supinating torque (1). in seven intact elbows, (2). after radial head excision, (3). after sequential resection of the coronoid process, (4). after subsequent insertion of each of two different types of metal radial head prostheses (a rigid implant and a bipolar implant with a floating cup), and (5). after subsequent reconstruction of the coronoid with each of two different techniques in the same cadaveric elbow. RESULTS: The posterolateral rotatory laxity averaged 5.4 degrees in the intact elbows. The surgical approach used in this study insignificantly increased the mean laxity to 9 degrees. Excision of the radial head in an elbow with intact collateral ligaments caused a mean posterolateral rotatory laxity of 18.6 degrees (p < 0.0001). Additional removal of 30% of the height of the coronoid fully destabilized the elbows, always resulting in ulnohumeral dislocation despite intact ligaments. Implantation of a rigid radial head prosthesis stabilized the elbows. However, a mean laxity of 16.9 degrees persisted after insertion of a floating prosthesis (p < 0.0001). The elbows with a defect of 50% or 70% of the coronoid, loss of the radial head, and intact ligaments could not be stabilized by radial head replacement alone, but additional coronoid reconstruction restored stability. CONCLUSIONS: The results of this study suggest that the coronoid and the radial head contribute significantly to posterolateral rotatory stability.     

Kinematics and stability of the Norway elbow: A cadaveric study

We investigated the effect of simulated muscle loading and the contribution of the radial head to stability of the Norway elbow in 6 cadavers using an electromagnetic tracking device. The kinematics of the elbow after implantation of the prosthesis were similar to the intact elbow in their valgus-varus orientation, however, the forearms were slightly externally rotated, probably due to a small amount of external rotation of the humeral components at the time of implantation. The valgus-varus laxity limit of the implants were greater than in the intact specimens averaging 8.0 and 5.6 degrees, respectively. Simulated muscle loading stabilized both the intact and the Norway elbows. Excision of the radial head after implant arthroplasty increased their valgus-varus laxity, suggesting that preservation of the radial head may be indicated if it is not too severely involved by the underlying disease process.

The laxity permitted by the prosthesis articulation is greater than that measured after implantation of the Norway arthroplasty. This suggests that the prosthesis may behave as an unconstrained arthroplasty. This should minimize the stress experienced by the bone-cement interface and may reduce the incidence of loosening. The laxity of the elbows after joint arthroplasty were only slightly greater than normal, possibly explaining the low incidence of prosthesis dislocation which has been observed with clinical use.     

Failure mechanisms in uncemented Kudo type 5 elbow prosthesis in patients with rheumatoid arthritis: 7 of 49 ulnar components revised because of loosening after 2-10 years

BACKGROUND: Both components of the Kudo type 5 elbow prosthesis can be inserted with or without the use of cement. There have been no reports on the use of this prosthesis with all components uncemented in patients with rheumatoid arthritis. PATIENTS AND METHODS: We reviewed 49 primary uncemented Kudo type 5 elbow prostheses, inserted in 36 patients with rheumatoid arthritis, after mean 6 (2-10) years. Patients were assessed clinically both pre- and postoperatively (pain, instability, motion, ulnar neuropathy) and radiographically. Furthermore, at the time of follow-up clinical outcome was assessed using the Elbow Function Assessment Scale. RESULTS: At review, 7 of 49 elbows had undergone revision because of symptomatic loosening of the ulnar component. In 42 unrevised elbows, clinical outcome was excellent in 29, good in 7, fair in 5, and poor in one. 31 of 42 elbows had no pain; 11 were painful at rest (VAS 1-2) and/or as a result of activity (VAS 1-8). With revision as endpoint, survival was 86% at 6 years. Intraoperative malpositioning of the ulnar component with a valgus or varus alignment of < 5 degrees was associated with worse survival. INTERPRETATION: We found an unexpectedly high rate of loosening of the ulnar component, which was associated with intraoperative malpositioning of the prosthesis. The ulnar component of this prosthesis should not be inserted without cement in patients with rheumatoid arthritis.     

Radial head arthroplasty with a modular metal spacer to treat acute traumatic elbow instability

BACKGROUND: The use of a metal radial head prosthesis to help stabilize an elbow with traumatic instability is appealing because internal fixation of multifragment, displaced fractures of the radial head is susceptible to either early or late failure. The newer modular prostheses are easier to size and implant, but their effectiveness has not been investigated, to our knowledge. METHODS: Twenty-seven patients in whom a radial head replacement with a modular metal spacer prosthesis had been performed to treat traumatic elbow instability were evaluated with use of the Mayo Elbow Performance Index (MEPI), the American Shoulder and Elbow Surgeons Elbow Evaluation Instrument (ASES), and the Disabilities of the Arm, Shoulder and Hand questionnaire (DASH). Radiographs were evaluated for arthrosis, periprosthetic radiolucency, and heterotopic ossification. RESULTS: Seven patients underwent one or more subsequent operations to treat residual instability, heterotopic ossification and elbow contracture, ulnar neuropathy, or a misplaced screw. In two of these patients, the prosthesis was removed as part of an elbow contracture release or to treat infection. At an average of forty months postoperatively, elbow motion in the entire group of twenty-seven patients averaged 131 degrees of flexion with a 20 degrees flexion contracture, 73 degrees of pronation, and 57 degrees of supination. Stability was restored to all twenty-seven elbows, and twenty-two patients had a good or excellent result according to the MEPI. Seventeen patients had radiographic evidence of lucency around the neck of the prosthesis that was not associated with increased pain, thirteen patients had clinically inconsequential heterotopic ossification anterior to the radial neck, and nine patients had radiographic changes in the capitellum. CONCLUSIONS: An intentionally loosely placed modular metal radial head prosthesis can help to restore stability in conjunction with repair of other fractures and reattachment of the lateral collateral ligament to the epicondyle in the setting of traumatic elbow instability with a comminuted fracture of the radial head. While a prosthesis that is too large can cause problems, lucencies around the stem of the intentionally loose prosthesis and most changes in the capitellum do not appear to cause problems, at least in the short term.     

Radial head prosthesis after fracture of radial head with associated elbow instability

Introduction: Fractures of the radial head and associated elbow instability can be treated with operation with radial head prosthesis. In this study, we evaluate function 1–7 years after implantation and also function after removal of five prostheses. Material and methods: Eighteen patients with radial head fracture and associated elbow instability were evaluated 3.7 years (1–7) after implantation of a radial head prosthesis. Pain at rest and during activity was measured with a visual analogue scale (VAS). Test of stability and neurological examination was done manually as well as measurement of the range of motion, using a goniometer. Activity of daily living (ADL) was estimated using five questions where the answers were graded between 1 and 3. The patients were asked to grade their general satisfaction according to the following scale; very satisfied, satisfied, not satisfied, disappointed. Plain X-rays were taken and 14 patients agreed to have their elbow strength evaluated using the validated BTE work simulator. Results: Five prostheses had been extracted due to poor range of motion. All these patients improved after extraction. All elbows were stable. No patient with extracted prosthesis had VAS score >2. The mean extension defect for this group was 15° (5–25) compared to the mean extension defect for the 13 patients with the prosthesis still in place 15° (0–40). The highest VAS score for the patients with prosthesis was five but the mean as low as 0.8. In the whole group, 13 patients were pain free. ADL function was good in general. The X-rays of the prostheses, still in place, showed radiolucent lines in 7 of the 13 patients. In the whole group, there was a significant decrease in supination, flexion and extension strength (P<0.01, P<0.01, P<0.05). Discussion: Radial head prosthesis works as a spacer after fracture of the radial head and associated instability. If range of motion is much restricted post-operatively, the prosthesis can be removed with improved function as result.     

Endoprothetik der akuten Radiuskopffraktur

Radial head arthroplasty is the treatment of choice for non-reconstructble radial head fractures. Solid prostheses made of metal or pyocarbon can restore valgus stability of the elbow independent of design or stem fixation. Short-term and mid-term results show mostly good to excellent results without any evident differences between the different prosthesis philosophies. In ordert to obtain good results it is important to implant the prosthesis correctly without overfilling and to judge concomitant ligament injuries correctly. This article discusses the anatomical and biomechanical basis of radial head arthroplasty as well as the surgical technique and radiological diagnosis of overfilling.     

Fractures of the capitellum

Forty intact cadaver elbows were studied to determine the contribution of the capitellum to elbow stability. With the elbow at 10 degrees of flexion, valgus motion of the elbow after capitellum excision demonstrated a minimal increase. Although some increase in valgus motion did occur after capitellum excision and radial head resection it was not until the ulnar collateral ligament was released that a severe valgus deformity was produced. In addition, isolated capitellum excisions occurring with release of the medial collateral ligament produced severe valgus motion, demonstrating the importance of medial structures to elbow stability. The cadaver study suggests excision of the capitellum in the otherwise intact elbow has little effect on valgus motion. Over the past 15 years, 17 patients with fractures of the capitellum were treated. Followup at greater than 1 year utilizing various treatment modalities is reported. Although closed reduction gave the best result, acceptable results were also obtained by open reduction and internal fixation and excision. Our clinical findings corroborated the cadaver findings in that valgus instability of the elbow only occurred when fracture of the capitellum was associated with medial ligament injuries.     

Successful outcome of the Souter-Strathclyde elbow arthroplasty

This study describes a consecutive series of 68 primary Souter-Strathclyde elbow replacements performed in a predominantly rheumatoid population, compares survivorship and complication profile with published series, and analyzes factors associated with successful outcome. Survivorship at 10 years was 74%, with at least 5 years' follow-up in 25 prostheses and a satisfactory Mayo score in 92% of all 68 elbows. These results compare acceptably with those from specialized elbow units. Careful component selection with regard to joint stability and bony fixation are important factors in the successful outcome of the Souter-Strathclyde arthroplasty. Use of a long-stemmed prosthesis was associated with a significantly better outcome after intraoperative fracture, and revision to a linked articulation was the most reliable treatment for instability.     

Radial head replacement in capitellocondylar total elbow arthroplasty. 2- to 6-year follow-up evaluation in rheumatoid arthritis

We reviewed six capitellocondylar metal-to-plastic total elbow replacement prostheses with radial head components, implanted in patients with rheumatoid arthritis. At an average of 4.7 +/- 1.5 years, relief of pain, improvement of function, and a functional range of motion were preserved. Five of the six elbows (83%) were clinically rated good or excellent. Radiolucent lines were seen at the bone-cement interface in 50% of the humeral component stems and in all ulnar component boats within 2 years after surgery; none had progressed at subsequent examination. Most were less than or equal to 1 mm wide, and none were associated with clinical deterioration. Only one of the humeral components was radiographically loose. No radiolucent lines were seen along the stems of the ulnar or radial components. There were no postoperative dislocations when the radial component was used, presumably because the prosthetic radial head provided increased constraint. None of these elbows have required revision. Radial head replacement in capitellocondylar arthroplasty had been discontinued because radiolucent lines were observed at early review. However, the absence of clinical failure, dislocation, or progression of radiolucency at long-term follow-up examination favor radial head replacement in primary unconstrained total elbow arthroplasty.     

Functional outcome comparison of semiconstrained and unconstrained total elbow arthroplasties

Twenty-six patients, each of whom had undergone either a semiconstrained (linked) or an unconstrained (unlinked) total elbow arthroplasty, were examined specifically to evaluate the restoration of function with respect to activities of daily living. The functional outcomes of these 2 groups were then compared to identify any significant differences. All of the unlinked/unconstrained prostheses were Ewald total elbow arthroplasties; the linked/semiconstrained prostheses, all of which were performed by a single surgeon, were Mayo-Coonrad prostheses. Follow-up radiographs, taken to rule out loosening or failure of the prosthesis as a cause for functional deficits, were available for review for 25 elbows. There were 14 elbows in 13 patients who had semiconstrained prostheses and 12 elbows in 10 patients who had unconstrained total prostheses. Average age at the time of elbow replacement surgery was 62.8 years (range, 47-75 years) for the semiconstrained group and 63.1 years (range, 54-74 years) for the unconstrained group. The semiconstrained group consisted of 8 female and 6 male elbows; the unconstrained group consisted of 10 female and 2 male elbows. Follow-up averaged 35.5 months (range, 24-73 months) in the semiconstrained group and 73 months (range, 27-110 months) in the unconstrained group. Twenty-two operations were performed for rheumatoid arthritis, 3 for posttraumatic humeral nonunion, and 1 for posttraumatic degenerative arthritis. Two elbows required revision, one (in the semiconstrained group) for aseptic loosening and the other (in the unconstrained group) for metal synovitis and pain from a chronically dislocated prosthesis; both of these elbows were considered failures and excluded from the functional comparison. No significant differences in functional performance were found, and no elbows demonstrated progressive radiolucencies suggestive of loosening. With the exception of 1 patient (in addition to the patients who had revisions) with a dislocated unconstrained prosthesis, all patients were satisfied with the procedure. It appears that when it is properly performed, total elbow arthroplasty with either type of prosthesis yields satisfactory functional results.     

Indikation und Ergebnisse nach Radiuskopfprothesen

Treatment of unreconstructible comminuted fractures of the radial head (Mason type III or IV) remains controversial. Radial head excision was advocated for the management of these severe fractures in the past. Complications such as valgus elbow instability, elbow stiffness, and proximal radial migration can be the result. There is limited information on the outcome of arthroplasty with a radial head implant. The functional outcomes of 19 patients with arthroplasty of the radial head were evaluated after an average of 40.4 months. According to the functional rating index (Broberg and Morrey), 2 results were graded as poor, 6 as fair, and 11 as good or excellent. The poor and fair outcomes were associated with concomitant injuries. Elbow flexion of the injured extremity averaged 121±15°, extension ?19±12°, pronation 76±17°, and supination 73±18°. Valgus stability was restored and proximal radial migration did not occur. Complications included two luxations, but no wound infection. Patients treated with radial head prosthesis for a severely comminuted radial head fracture have mild to moderate impairment of the elbow and wrist. Arthroplasty with a radial head prosthesis was found to have been a safe and effective treatment option.     

Long-term results with the Kudo type 3 total elbow arthroplasty

From 1992 to 1993, 17 elbows were replaced with the unlinked Kudo type 3 total elbow arthroplasty in 16 patients with arthritic joint destruction. Of these elbows, 8 were available for clinical examination after a mean of 9.5 years. Of the 17 elbow implants, 5 were revised: 2 because of loosening of the ulnar component, 1 because of dislocation, 1 because of a periprosthetic fracture, and 1 because of a late deep infection. At 9.5 years' follow-up, 67.9% of the prostheses had survived, and the mean survival of the implant was 8.7 years (95% confidence interval, 7.5-10 years). In this study, we observed high rates of progressive valgus tilting of the ulnar component. This valgus tilting is of major concern because it provides more stress to a smaller area on the polyethylene. It may, therefore, cause an increased degree of polyethylene wear and, thereby, reduce the final implant survival rate.     

Capitellum excision: Mechanical implications and clinical consequences

Controversy exists regarding the optimal treatment of isolated fractures of the capitellum that are not amenable to open reduction and internal fixation. Excision of the capitellum could result in instability of the elbow, though only limited the clinical or laboratory evidence exists to support this outcome. The aim of our study was to determine if capitellum excision leads to significant instability by measuring the relative change in varus–valgus displacement of the elbow. The varus–valgus displacement was recorded in 11 cadaveric elbows before and after isolated excision of the capitellum. Specimens were testing in varus‐loaded and valgus‐loaded positions with and without a 1 kg weight on the forearm. The varus–valgus displacement at the elbow was measured using a 3D motion capture system. Capitellum excision did not significantly change varus–valgus displacements in either the adducted, varus, or valgus position of the elbow (p = 0.80, p = 0.28, p = 0.51). Furthermore, the addition of the 1 kg external functional load to the forearm did not produce a significant change in the varus and valgus loaded positions (p = 0.16, p = 0.36). Our results demonstrate that excision of the capitellum in the setting of intact ligamentous structures does not result in significant instability in either the adducted varus loaded or valgus loaded positions of the elbow. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 32:346–350, 2014.