There have been many described techniques for distal biceps tendon repair. Historically, authors have favored a two-incision approach popularized by Boyd and Anderson [5
]. This technique relies on fixation of the distal biceps tendon into a trough at the radial tuberosity with sutures tied over a bony bridge. This technique can be associated with nerve injury [17
], heterotopic ossification [9
], and radioulnar synostosis [22
]. A single-incision anterior approach with the use of suture anchors or interference screw fixation has become popular in recent years [3
]. However, there are technical challenges associated with knot-tying and tendon tensioning in a muscular forearm or with chronic repairs.
Repair of distal biceps tendon ruptures with an EndoButton was first described by Bain for use in a single-incision anterior approach [2
]. Advantages include less technical difficulty in securing fixation through a single anterior incision, a bone socket to maximize healing, and strong fixation allowing early motion. The higher load to failure of the EndoButton technique has been shown in several studies [18
] and is associated with cortical bone based fixation through the dorsal aspect of the radius. The EndoButton has been shown to have higher load to failure than interference screws, suture anchors, and transosseus tunnels [6
]. Strong initial fixation of the biceps tendon to the radial tuberosity bone socket allows for aggressive early range of motion. In our study, all patients regained fully functional range of motion.
Clinical results of EndoButton repair are also encouraging [2
]. Bain et al. [2
] reported satisfactory outcomes with early active mobilization in all 12 patients with no complications. All patients regained grade 5 strength and returned to full activities. Peeters and colleagues [28
] recently reported on 26 patients who underwent EndoButton repair of distal biceps tendon ruptures. Average flexion strength recovery was 80% and supination strength recovery was 91%. Greenberg et al. [11
] reported on 14 patients at an average follow-up of 20 months. Strength testing demonstrated return of 97% flexion and 82% supination strength when compared to the non-operative arm. Ranelle [30
] reported on 11 men and one woman who underwent repair with an EndoButton. All patients returned to their prior activity level with no complications. Our study demonstrated similar results with 26 of 27 patients returning to their previous employment and activity level. Using conversion factors generated from eight control subjects, there was only a 1% supination strength deficit and a 2% flexion strength deficit when comparing the operative extremity to the uninjured arm.
There have been few reports of outcomes after chronic distal biceps tendon repairs. Most techniques advocate the use of a tissue graft including semitendinosis tendon [13
], achilles tendon [8
], flexor carpi radialis tendon [23
], and fascia lata [16
]. Our study reports nine patients with a chronic rupture of the distal biceps tendon (mean of 3 months from injury). Our data show that repair can be performed without
the use of allograft or autograft tendon augmentation in chronic ruptures up to 6 months old. We found complete restoration of motion, strength and endurance when compared to the non-operative extremity. We also suggest that patients will regain full motion even if the repair is completed with the elbow in a significant amount of flexion because of the biceps muscle elasticity. Although further studies are in progress to examine the outcomes of chronic repairs performed without graft augmentation, there are obvious advantages of avoiding the use of allograft or autograft, which include the lack of autograft donor site morbidity and no risk of allograft disease transmission.
The effect of hand dominance on the outcome following repair of distal biceps ruptures has rarely been addressed. Agins and colleagues used a two-incision technique to demonstrate that repaired non-dominant extremities were 46% weaker in flexion following repair when compared to the uninjured dominant extremity [1
]. Leighton et al. [22
] reviewed nine patients and examined the role of hand dominance on outcome. Three dominant extremities demonstrated complete return of strength and endurance in both flexion and supination. However, repair in six non-dominant extremities demonstrated deficits in flexion strength, flexion endurance, and spination strength. D’Alessandro et al. noted weakness with flexion endurance in the dominant extremity and loss of supination endurance in non-dominant extremities [7
]. The role of hand dominance in strength and endurance recovery and postoperative pain may alter the pre-operative discussion regarding expected outcomes.
Lateral antebrachial cutaneous (LABC) sensory deficit may be due to the increased dissection that is required to mobilize the tendon in chronic injuries or secondary to increased tension on the repaired tendon stretching the LABC nerve. Patients should be warned about this potential complication when repair of a chronic rupture is performed.
The weaknesses of this study include that it is retrospective. Additionally, only 27 patients were available for follow-up examination and strength testing, although this is still the largest study of this technique to date. Pre-operative DASH scores, along with pre-operative strength and endurance testing, could have provided additional information of interest. While providing little additional insight into those patients with an acute rupture, such data could prove beneficial when examining those with chronic injuries.
EndoButton fixation of distal biceps tendon ruptures is a safe and effective method of treatment with excellent clinical results. Patients demonstrate full recovery of range of motion and near complete return of strength and endurance with a low complication rate. This technique is ideal for repairing chronic ruptures without the need for allograft or autograft augmenation.