A biomechanical study on fracture risks in ulnohumeral arthroplasty

Long-term survivorship of open débridement and débridement arthroplasty for elbow arthritis: a retrospective chart review

BACKGROUND

Open débridement and Outerbridge-Kashiwagi (OK) débridement arthroplasty (OK procedure) are common surgical treatments for elbow arthritis, but little is known about their long-term survivorship. The purpose of this study was to determine whether survivorship until conversion to total elbow replacement and revision surgery was better for the OK procedure compared with open débridement.

METHODS

We performed a retrospective chart review of patients who underwent open elbow surgical débridement (open débridement or OK procedure) between 2000 and 2015. Patients received a diagnosis of primary elbow osteoarthritis, post-traumatic arthritis, or inflammatory arthritis. A total of 320 patients underwent surgery including open débridement (n = 142) or the OK procedure (n = 178), and of these patients, 33 required secondary revision surgery (open débridement, n = 14; OK procedure, n = 19). The average time since surgery was 11.5 years (range, 5.5-21.5 years). Survivorship was analyzed with Kaplan-Meier curves and the log rank test. A Cox proportional hazards model was used to estimate the effect of the type of procedure, index diagnosis, age, and sex on survivorship.

RESULTS

Kaplan-Meier survival curves showed survivorship rates until total elbow arthroplasty of 100.0% at 1 year, 99.3% at 5 years, and 98.5% at 10 years for open débridement and 100.0% at 1 year, 98.8% at 5 years, and 98.0% at 10 years for the OK procedure (P = .87). There was no difference in survivorship between procedures, even after adjustment for significant covariates. The rates of revision for open débridement and the OK procedure were similar, at 11.3% and 11.5%, respectively, after 10 years. Higher rates of revision surgery were observed in patients who underwent open débridement (hazard ratio, 4.84; 95% confidence interval, 1.29-18.17; P = .019) compared with those who underwent the OK procedure after adjustment for covariates. We performed a stratified analysis with radiographic severity as an effect modifier and showed that patients with grade 3 arthritis fared better after the OK procedure compared with open débridement in terms of survivorship until revision surgery (P = .05). However, such a difference was not found for grade 1 or grade 2 arthritis.

CONCLUSION

We showed that both open elbow débridement and the OK procedure had excellent survivorship until conversion to total elbow arthroplasty and are viable options in the treatment of primary elbow osteoarthritis and post-traumatic cases that could help delay the need for total elbow arthroplasty. Patients with more severe radiographic arthritis, specifically grade 3 arthritis, were less likely to require revision surgery if treated initially with the OK procedure compared with open débridement.

The effect of hole size on failure loads of the distal humerus fenestration in Outerbridge-Kashiwagi arthroplasty: A biomechanical study

OBJECTIVE

The aim of this study was to biomechanically assess the effect of humeral-fenestration size in the Outerbridge-Kashiwagi arthroplasty on the ultimate failure load of the distal humerus in a synthetic bone model.

METHODS

We biomechanically tested the influence of different humeral-fenestration sizes on the failure load of the distal humerus in Outerbridge-Kashiwagi arthroplasty. A total of 50 synthetic humerus models were divided into 5 groups based on the fenestration size: 10 mm, 12 mm, 15 mm, 18 mm, and 20 mm. All the samples were randomly assigned to receive either axial or anteroposterior (AP) loading and then loaded to failure at a rate of 2 mm/min on a material testing machine. The data regarding ultimate failure loads under the axial and AP loading were analyzed.

RESULTS

Under the AP loading, the mean ultimate failure loads of the 18 mm and 20 mm groups were lower than those of the other groups. Under the axial loading, the mean ultimate failure load of the 10 mm group was significantly greater than that of the 15 mm, 18 mm, and 20 mm groups. Additionally, the ultimate failure load of the 20 mm group was significantly lower than that of the 12 mm, 15 mm, and 18 mm groups.

CONCLUSION

The distal humeral fenestrations with a size greater than 18 mm may offer poor biomechanical properties in the Outerbridge-Kashiwagi ulnohumeral arthroplasty.

Fracture Risk in Ulnohumeral Arthroplasty-A Biomechanical Study

PURPOSE

Ulnohumeral arthroplasty, also known as the Outerbridge-Kashiwagi procedure, was popularized after reports of successful results in 1978, and has long been a means of management for ulnohumeral arthritis. However, there are concerns over the loss of integrity of the distal humerus as a result of fenestration. The purpose of this study was to examine the relationship between the size of fenestration and fracture risk.

METHODS

Using a validated fourth-generation sawbones model, load to failure and site of fracture were investigated following incrementally increasing distal humeral fenestration sizes. Each sample was subjected to a uniform extension stress on a materials testing system, with 5 samples run for each group. The experimental groups began with a fenestration size of 10 mm and increased by 3 mm increments up to 31 mm. Load at failure and site of fracture were recorded for each sample.

RESULTS

Forty-five fourth-generation sawbones samples were tested. Average load at sample failure was equivalent for each fenestration group up to 25 mm. At 28 mm, average load to failure began to decrease, and was statistically significant beginning between 28 mm and 31 mm. At 28 mm, 4 of 5 samples fractured through the fenestration, and at 31 mm, all 5 samples fractured through the fenestration. This change in fracture site became statistically significant between 25 mm and 28 mm.

CONCLUSIONS

Distal humeral fenestration does compromise its structural integrity; however, for resection in the range of 10-25 mm, there is no increased risk of fracture.

CLINICAL RELEVANCE

On the basis of this biomechanical model, the authors do not recommend any activity limitations after initial surgical recovery, but do recommend against distal humeral fenestrations larger than 25 mm when performing this procedure.

The effect of humeral-fenestration diameter in Outerbridge-Kashiwagi arthroplasty on failure load of the distal humerus: a cadaveric biomechanical study

INTRODUCTION

Outerbridge-Kashiwagi ulnohumeral arthroplasty is an effective method in treating elbow osteoarthritis; however, distal humerus fracture after surgery can become a critical issue. A previous biomechanical study has shown that the failure load of the distal humerus decreases after a fenestration, but the size of the fenestration hole has not yet been discussed.

MATERIALS AND METHODS

32 fresh-frozen cadaveric distal humeri were obtained. Two drill sizes were chosen for fenestration: 12 and 15 mm in diameter. Two directions of force were applied with a materials testing machine for biomechanical testing: 5° flexion for axial loading and 75° flexion for anterior-posterior (AP) loading. Each specimen randomly received one of the two fenestration sizes, and force directions. All specimens were loaded to failure at a rate of 2 mm/min.

RESULTS

The failure loads of the 12 and 15 mm groups were not significantly different in either axial loading(3886 ± 1271 N vs 4286 ± 901 N) or AP loading(2303 ± 803 N vs 1897 ± 357 N). All specimens loaded with axial force failed via the fenestration holes; however, during AP loading, some specimens failed through the fenestration holes, while others at diaphysis (p = 0.28).

CONCLUSIONS

The failure load of distal humeri did not differ significantly after fenestration of 12 or 15 mm. The clinical relevance is that as the risk of distal humerus fracture is not exacerbated, a larger-size fenestration hole could be of help to improve the effectiveness of this surgical procedure.

Arthroscopic Management of Elbow Osteoarthritis

The incidence of osteoarthritis in the general population is low, but it can be seen in manual laborers, throwing athletes, and people dependent on crutches and wheelchairs. Patients often complain of pain at the terminal extents of motion, and imaging shows osteophyte formation at the tips of the coronoid and olecranon processes as well as thickening of the bone between the coronoid and the olecranon fossae. Recent advances in arthroscopic instrumentation and techniques have led to a growing interest in the arthroscopic treatment of elbow osteoarthritis. This article provides a review of basic arthroscopic elbow anatomy and the most common procedures, including diagnostic arthroscopy, loose body removal, and arthroscopic osteocapsular and ulnohumeral arthroplasty. As techniques advance, there might be interest in further procedures including arthroscopic-assisted interpositional arthroplasty. Although complications such as persistent drainage and nerve injury are frequently mentioned with elbow arthroscopy, the actual incidence of such complications remains low.

The arthroscopic ulnohumeral arthroplasty: from mini-open to arthroscopic surgery

In cubarthritis-osteoarthritis of the elbow-surgical procedures may be considered to debride the elbow joint to reduce pain, to increase mobility, and to postpone joint replacement surgery. The ulnohumeral arthroplasty as described by Outerbridge and Kashiwagi was originally introduced to debride both anterior and posterior elbow compartments through a direct posterior mini-open approach. To achieve this, a distal humeral fenestration throughout the humeral fossa is performed. Although with an elbow arthroscopy, a technique that was obviously developed later on, all compartments can be easily visualized. The arthroscopic fenestration of the humerus preserves its advantages, with good clinical results focused on pain relief and gaining mobility. On top, future elbow joint locking based on degenerative loose bodies can be prevented. Therefore, this surgery is often done in young, more active patients and even in sportsmen. These patients, however, need to be prompted to restrict loading on the elbow in the immediate postoperative period, because the elbow is biomechanically weakened and may be prone to a fracture. However, both outcome and postoperative rehabilitation are promising and the arthroscopic Outerbridge procedure is a reliable procedure with an easy rehabilitation. Therefore, the threshold is relatively low in early cubarthritis and recurrent locking of the elbow. In this paper, we present a literature review and the author's experience and own research on the Outerbridge procedure.