Distal biceps hook test – Sensitivity in acute and chronic tears and ability to predict the need for graft reconstruction

Abstract

Background

The aim of this study was to assess the sensitivity of distal biceps hook test – O’Driscoll hook test – in a retrospective series of acute and chronic distal biceps tendon tears and investigate the ability of the test to predict the need for graft reconstruction.

Methods

We retrospectively evaluated 234 consecutive distal biceps tendon tears operated in a single centre. The result of O’Driscoll hook test and perioperative findings of distal biceps were documented in standard fashion.

Results

The perioperative and O’Driscoll hook test data were available in 202 cases. The sensitivity for the distal biceps hook test was 78% in all tears and 83% in complete tears. The sensitivity was significantly lower in partial tears (30%) and in cases where lacertus fibrosus was found to be intact (45 %). When O’Driscoll hook test was positive and the delay from initial injury to operative intervention was eight weeks or more, there was over 75% probability of achilles tendon allograft reconstruction. When O’Driscoll hook test was negative, the probability of reconstruction even after 12 weeks’ delay was only 20%.

Discussion

O’Driscoll hook test is useful when establishing distal biceps tendon tear diagnosis, but a negative test does not exclude rupture. In delayed cases, a positive test may predict the need for reconstruction.

Introduction

The incidence of distal biceps tendon tear (DBTT) has been increasing in the last few years. This could be attributed to better diagnostic tools available to the clinician.^1,2 The DBTTs appear in a wide spectrum ranging from degenerate fissuring associated with tendinosis, partial thickness tears, complete tear with sheath intact, complete tear with lacertus intact and ruptures of the tendon including lacertus fibrosus.^3,4 Of these, complete rupture at the tendon to bone interface is the most common type of injury. DBTTs have been classified as partial (insertional or intrasubstance) or complete tears, or – based on delay from initial injury – as acute for less than four weeks duration and chronic of more than four weeks.³ The diagnosis of a DBTT is both clinical and radiological.^4,5

A clinical tool – ‘the O’Driscoll hook test’ (OHT) – was described by O’Driscoll et al.⁴ In this test, the patient actively supinates the forearm with arm elevated 90° and the elbow flexed 90°, and the examiner tries to hooks his or her index finger under the intact biceps tendon from the lateral side. If there is a lack of a cord-like structure under which the examiner may hook a finger, it indicates distal avulsion. The authors report sensitivity and specificity as high as 100% in their article.⁴ The use or sensitivity of OHT has not been validated in other studies.

Delay to diagnosis or presentation occurs frequently which may cause a challenge as the muscle is prone to retract, and over time in complete ruptures with a torn lacertus the tendon may become irreparable. If operative intervention in these chronic cases is considered, the surgeon usually needs to be prepared for reconstruction with auto- or allograft, which makes the operation more challenging.^6–9 In the past, the time from initial injury was considered a significant factor to define the need for reconstruction. The use of an allograft has been recommended when anatomic repair cannot be achieved by native tendon beyond 70° to 90° flexion or when the structure of the tendon itself does not allow direct repair.¹⁰ As such, the decision to proceed to reconstruction has been evaluated perioperatively. The use of both auto- and allografts as well as synthetic grafts for reconstruction have been described in the literature.^7,9–11 There is a lack of comparative studies to demonstrate superiority of one graft over other. In addition, the understanding of predictive factors for the need of reconstruction is scarce.

The purpose of this study was to evaluate the sensitivity of distal biceps hook test and its ability to predict the need of reconstruction.

Methods

After institutional and local ethics committee approval, 234 consecutive cases operated in single centre under the care of the senior author between 1 April 2010 and 31 March 2017 were retrospectively evaluated. Inclusion criteria were operatively treated total or partial acute or chronic DBTT. Exclusion criteria were missing OHT results in the case notes or previous operation of ipsilateral biceps tendon. The indications for operative treatment were (1) reduced elbow flexion or forearm supination strength or (2) continuous pain or (3) continuous cramping of the distal biceps.

All patients were assessed with standardized methods. The following symptoms and signs were evaluated and reported in medical records: (1) pain, (2) haematoma, (3) nerve symptoms, (4) the findings under palpation of the distal biceps tendon and lacertus fibrosus, (5) the O’Driscoll Hook test (4), (6) distal biceps ultrasound if applicable or (7) plain magnetic resonance imaging (MRI) or flexion abduction supine position-MRI if necessary.

Operations were performed under the supervision of a single experienced surgeon using standardized methods. The primary repairs were done using the technique described by Bain et al.¹² and achilles tendon allograft reconstructions with technique described by Phadnis et al.¹¹

The decision between the direct repair and allograft reconstruction was made by the senior author. Direct repairs were undertaken even if the elbow needed to be flexed more than 90°. This was possible because of the pull-through technique used. However, reconstruction was performed in situations where the tendon and lacertus fibrosus were torn, the tendon involuted into the muscle belly and was atrophied rendering direct repair impossible.

The sensitivity of the test was calculated as the proportion of positive test results in six categories based on findings in the operation: (1) all ruptures, (2) complete ruptures with retraction, (3) complete ruptures without retraction, (4) partial ruptures, (5) intact and (6) torn lacertus fibrosus. The proportion (risk) of allograft reconstructions was calculated separately in four groups: delay of 0–4 weeks, 4–8 weeks, 8–12 weeks and >12 weeks.

Results

Two hundred and thirty-four consecutive DBTT cases were retrospectively identified from our institution database. Four patients were excluded because of the previous repair. Hook test results were available for 202 cases. Of these, 162 cases underwent direct repair and 40 were reconstructed with achilles tendon autograft. A total of 182 patients had complete tear and 20 had partial tear. Demographic data of the operated patients is described in Table 1.

Table 1.

Descriptive statistics of study population

Age, years (SD; range)	42 (11; 20 to 85)
Gender
Male	201
Female	1
Side of injury
Right	125
Left	77
Physical activity level
Elite sports	43
Heavy manual	32
Intermediate manual	56
Light office	63
N/A	8
Type of repair
Direct repair	162
Reconstruction	40

The overall sensitivity for OHT was 80% in all tears and 86% in complete tears. The sensitivity was lower in cases where lacertus fibrosus was found to be intact (45%) during the operation and in partial tears (30%). OHT was equivocal in nine cases, of which seven were complete tears with no retraction and complete tears with retraction. In 4 of 29 cases with equivocal test result, the lacertus was intact. The sensitivity of OHT in each category is summarized in Table 2.

Table 2.

Sensitivity of distal biceps hook test in relation to tear type and preserved anatomical structures.

Tear type	Sensitivity	Equivocal test
All tears	162/202 (80%)	9/202 (4%)
All complete tearsa Complete tear +  retraction Complete tear +  no retraction	156/182 (86%) 84/91 (92%) 67/86 (78%)	9/182 (5%) 2/91 (2%) 7/86 (8%)
Lacertus fibrosus intact	13/29 (45%)	4/29 (14%)
Lacertus fibrosus torn	149/173 (86%)	5/173 (3%)
Partial tears	6/20 (30%)	0/20 (0%)

LF: lacertus fibrosus.

^aMissing data of five cases regarding retraction.

A positive OHT in conjunction with delay to surgery was predictive of a need for graft reconstruction (Table 3). When OHT was positive and the delay from initial injury to operative intervention was eight weeks or more, there was over 75% probability that the patient would undergo graft reconstruction. On contrary, when OHT was negative, the probability of reconstruction even after 12 weeks delay from injury was only 20%.

Table 3.

Risk for graft reconstruction based on hook test in relation to delay from initial injury to operation

Time (weeks)	Risk, Hook test +	Risk, Hook test −
0 to 4	4/110 (4%)	0/17 (0%)
5 to 8	2/10 (20%)	0/2 (0%)
9 to 12	3/4 (75%)	0/3 (0%)
>12	29/37 (78%)	2/10 (20%)

Discussion

DBTTs are diagnosed by clinical examination or radiological imaging or both.^4,13,14 Historically, DBTT diagnosis has been delayed or commonly missed.^6,15,16 As a consequence, O’Driscoll et al. developed a clinical test which has been widely accepted as a useful test to diagnose DBTT. In their study, the authors meticulously describe how to perform and interpret the test and explain the pitfalls. The authors found that OHT was abnormal in 33 of 33 in complete avulsions, and in addition it was intact in 12 of 12 of the partial tears. The contralateral biceps served as a control. As such, they concluded that both sensitivity and specificity of the test were 100%.⁴ This is problematic especially regarding the specificity as usually medical tests are performed in conditions where pathological condition is suspected (for example haematoma, pain) but not yet diagnosed. Another test – similar to Simmond’s test used in Achilles tendon ruptures – a biceps squeeze test, was described by Ruland et al.¹³ In this test, the distal biceps is squeezed with the forearm resting in the patients lap with elbow in 90° of flexion and forearm supination is monitored. If no passive supination is observed, the test is considered positive. The sensitivity of the test was reported to be 95%.¹³ To our knowledge, the sensitivity of neither test has been validated in another data set.

For the purposes of this study, the OHT was performed as described in the original article. An overall sensitivity of 80% was observed with the highest (86%) for complete tears with retraction. (Table 2) The negative results might be explained by the fact that in some tears the tendon sheath (Figure 1) or lacertus fibrosus may remain intact giving an illusion of intact tendon as it is held out to length. An intact lacertus fibrosus was a confounding factor yielding negative test results in 45% of the cases (Table 2). In these cases, the OHT may be negative but the “cord” that is hooked may feel different to the contralateral side and may lie more medially due to the abnormal attachment point. If surgery is delayed in these cases, the tendon usually becomes scarred in the antecubital fossa.

Figure 1.

Flexion abduction supination (FABS) resonance imaging showing a complete intra sheath distal biceps tear (white narrow arrow) with lacertus fibrous tear (white thick arrow) in a patient with negative O'Driscoll Hook Test.

The present study found that OHT was positive in 30% of partial tears (Table 2). If we assume that a partial tear should yield negative OHT result, then the calculated sensitivity should be considered as false positive rate. The test is clearly not well suited to recognize the partial tears as the partially unattached distal tendon may be slack and give positive result or be sufficiently taut to yield negative result. In these cases, the biceps squeeze test is likely to be negative and may be useful. The history and pain provoked by OHT or resisted forearm supination should raise concern and lead to further investigation. OHT was equivocal in 4% of cases and these were mostly tears with no retraction and an intact lacertus fibrosus.

In the literature, DBTTs are categorized as acute (under four weeks) and chronic (over four weeks).³ In chronic DBTTs, there are many factors influencing the surgical management such as retraction of the tendon and atrophy.¹⁰ In the past, it was believed that some kind of augmentation would be required for repair all chronic tears. However, current evidence suggests that augmentation needs to be done only when there is no tendon structure left or in cases of extreme retraction.¹⁷ Morrey et al. have described primary repair of retracted tendon also in extreme flexion even in chronic cases with good functional outcomes, whereas Darlis and Sotreanos suggested the use of an allograft when anatomic repair cannot be achieved by native tendon beyond 70° to 90° flexion.^10,18

On the other hand, the decision to perform reconstruction is based in clinical practice on an on-table estimation by the operating surgeon.

We found out that the result of hook test in conjunction with the delay between initial injury and operation can be used to prepare the patient for reconstruction. The need for graft rose sharply from 20% to 75% if the patient had over eight weeks of delay when the hook test was positive. On the contrary, when the hook test was negative, the risk of having a graft reconstruction was low (20%) even after 12 weeks. (Table 3) Occasionally, the structure of the tendon defines the need of reconstruction despite the delay to operation and outcome of hook test. We observed six cases needing reconstruction under eight weeks from the initial injury.

This study has limitations. The data is retrospective and the decision to perform surgery and the decision whether to undergo direct repair or use graft was defined by one surgeon, and hence the results may represent a single practice. In addition, the OHT as well as the interpretation of perioperative findings were made by the operating team. These may have caused selection as well interpretation bias. In addition, as the study setup is retrospective and the confirmation of diagnosis was based on observation in operating theatre, the team may have missed some of the ruptures, and thus the sensitivity could also be slightly lower than estimated. Also this data did not allow calculation of the specificity of the OHT. To evaluate the specificity of the test, it should be investigated in population containing all cases where the condition (DBTT) is suspected but not necessarily confirmed.

The strengths of this study are that it includes a relatively large data set considering the general incidence of this condition. It is also to date the only publication validating the sensitivity of OHT beyond the original publication.⁴ The study included a heterogenic population including patients with various activity levels and with both acute and chronic tears. The OHT was performed by a single team in standardized fashion meticulously as described in original article.⁴ In addition, the perioperative findings were reported in a structured way.

We conclude that OHT sensitivity is not 100% as described previously but it is still a useful clinical test to assess patients with suspected DBTT. A negative test does not exclude DBTT and further imaging is required in cases of doubt. Furthermore, in delayed cases, the positive result of OHT may be used to counsel the patient of the risk of graft reconstruction.

Declaration of Conflicting Interests

The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: ACW has received grants for research from Tornier/Wright Medical and receives payment for teaching from Wright Medical.

Ethical review and patient consent

This study was conducted after institutional ethical board approval. IRAS project ID: 227104. REC reference number: 17/NW/0287.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.