Distal Biceps tendon ruptures still remain challenging to diagnose in clinical practice for many physicians. Especially diagnosing if it is complete or partial distal biceps tear in clinical setting in some cases is still difficult even for many experienced clinicians. Doing that without having proper imaging like Ultrasonography or MRI is even more challenging. Prompt diagnosis is very important, as every week of its delay significantly change outcomes and increase risk of complications after surgical treatment.
To diagnose not only if it is complete tear but also if it is partial tear we added to our examination routine modification to the hook test that was previously described in 2007 by Shawn O’Driscoll et al. Modification of the hook test “Resisted Hook Test” is simple and quick maneuver that can help clinicians to proper and quick diagnosis. Adding this modification to our routine allowed us to establish algorithm for diagnosing distal biceps tendon tears using both hook test and resisted hook test , including diagnosing partial and complete tears and having ability to differentiate between them. We hypothesized that that the painful or absent hook/resisted hook tests are efficient tests to diagnose partial and/or complete biceps of distal tendons ruptures. Further, we sought that this information could be used for diagnosing during routine clinical patient examination.
**MATERIAL AND METHODS **
89 distal biceps repairs in 84 consecutive patients who were evaluated and explored surgically for a known or possible partial or complete avulsion of the distal biceps tendon from July 2003 to December 2018 by the senior author (SOD) were reviewed after institutional review board approval. The patients were identified from a surgical registry in which all operative cases of the senior author are recorded prospectively, beginning at each patient’s pre-surgical visit. This includes dates, indications, pre-operative, perioperative and post-operative clinicals and patients outcomes. An independent reviewer (MJH), not involved in these patients, reviewed the records, clinical notes, operative notes, imaging for documentation of the hook test throughout the peri-operative period and correlated with the surgical findings. The resisted hook test had become a standard component of the senior author’s clinical physical assessment of biceps repairs by “**What DATE”**. Thus, all the patients who underwent biceps tendon repair to this date were excluded. All patients undergoing revision of biceps tendon tears were excluded. All the patients (62 tendon repairs) were personally examined by the senior author (SOD), who also performed hook test, dictated clinical note on each patient personally and performed all the surgeries by himself.
The resisted hook test was performed in a blinded fashion. In other words, the findings of the hook test were determined before MRI or before viewing the MRI scans if the patients brought them.
Total of 60 patients undergoing 62 repairs formed the study cohort for this report. Partial and complete tendon repairs were included. Biceps avulsions were defined as complete if there were no tissues in continuity between the end of the biceps tendon and the radial tuberosity, such that the tendon could be retrieved from the would without surgical release of tissues.
If there were even small fibers attached to the radial tuberosity and there was need to surgically release the tendon from the wound, it was described as the partial tear of the distal biceps tendon.
**The Hook Test**
A detailed description of how to perform the hook test was previously described by the senior author. Briefly, the patient is asked to raise the arm in front of the face and to “look at the palm of your hand” (actively flex the elbow to 90° and supinate the forearm) while sitting or standing and to fully supinate the forearm to its end point of supination. For examining the right elbow, the examiner’s left index finger is brought in from the lateral side of the antecubital fossa beneath the lateral edge of the biceps tendon in an attempt to hook the tendon (Figure 1). With an intact biceps, the finger can be inserted beneath the tendon approximately 1 cm and in some cases right up to the distal interphalangeal joint of the examiner’s finger. This allows the examiner to fully “hook” the biceps tendon and pull it forward. For the left elbow, the examiner simply switches hands and performs the same maneuvers in a mirror image.
**Resisted HOOK TEST:**
The “Resisted HOOK TEST” is a further modification from our original description of the hook test. It is performed by instructing the patient, “Don’t let me move your hand” while applying a pronation torque to the hand in the supinated position, and repeating the hook test. The “Resisted hook test” is used to elucidate pain in a partially detached tendon or to permit the tendon to ‘stand out’ and be hooked when it is mostly detached and appears absent on initial testing (Figure 2).
There are three categories into which patients can be grouped into based on their hook test result: INTACT, ABNORMAL (PAINFUL) or ABSENT. This represents a change in the conventional terminology originally described in 2007. An INTACT tendon is a cord-like structure, behind which the examiner can place the index finder from the lateral side and “hook” the tendon to pull the patient’s arm downwards (hookable). If the biceps tendon is completely avulsed distally, the hook test result is “ABSENT” as there is no cord-like structure under which the examiner may hook a finger from the lateral side of the antecubital fossa (unhookable). If the hook test suggests an intact biceps tendon, the examiner should pull vigorously on the tendon, and also push the tendon inwards and from side-to-side, to evaluate for an “ABNORMAL ” hook test result.
A painful response, with an apparently intact tendon, suggests a partial tear. If the examiner is able to hook the tendon as described above, and this does not produce a pain response, the hook test result is described as “intact”.
The average patient age was 50 years (range, 30-79 years). 22 repairs were for partial biceps tendon avulsions, 40 were complete. Left side 35 patients, Right side 27 patients.
Average complete retraction in complete tears was 5 cm and average in partial tears group was 1 cm.
The hook test was clearly documented preoperatively for 62 of 62 repairs (60 of 60 patients). The contralateral hook test was documented in 62 of 62 repairs (60 of 60 patients).
38 of 40 complete tears (95%) had an ABSENT hook test.Those 2 patients who had abnormal hook test and hookable resisted hook test in complete tears had intact lacertus fibrosus. From all complete tears patients 3 of 40 (8%) had ABSENT resisted hook tests (2 patients) and 1 patient had hookable resisted hook test. Nine of all 40 complete tears (23%) had INTACT lacertus fibrosus.
22 partial tears (100%) had an ABNORMAL hook test/resisted hook test at preoperative examination and
From all partial tears 11 of 22 (50%) partial tears had ABNORMAL resisted hook test specifically. 19 of 22 (86%) partial tears had intact lacertus fibrosus.
Fifty-three patients had MRI preoperatively. In our practice we do not have in our routine ordering MRI for diagnosis confirmation of distal biceps tendon ruptures. 30 of 32 (94%) complete tears had been confirmed by MRI (two patients had partial tear diagnosis by MRI and post-op diagnosis of complete tear). 19 of 21 patients (90%) with partial tears had been confirmed by MRI (two patients had complete tear diagnosis by MRI and post-op diagnosis of partial tear). Thus, sensivity and specificity for MRI were 94% and 90% respectively. 2 patients with wrong preoperative MRI description of complete tears had absent hook test and absent resisted hook tests respectively – confirming the post-op diagnosis. 2 patients with partial tears with misleading diagnosis by MRI of complete tears had painful hook test and painful resisted hook tests respectively – confirming the post-op diagnosis.
In the contralateral arms, which served as the normal control group, 61 of 62 (98%) had a normal hook test. One patient had ABSENT hook test on his contralateral extremity because he had spontaneous rupture 5 years earlier which was treated non operatively.
We developed Algorithm that can guide clinical to diagnosing primary distal biceps tendon tears.
Unhookable ABSENT hook test indicates that there is no tendon in antecubital fossa behind examiner can hook his finger. In that situation examiner should perform resisted hook test. If there is ABSENT resisted hook test it indicates that it is complete distal biceps tendon rupture.
Hookable hook test with no pain reproduced suggests that the distal biceps tendon is INTACT.
ABNORMAL (Painful and hookable) hook test is indication of partial tears. However if examiner perform hook test that is unhookable and afterwards perform resisted hook test which is hookable that strongly indicates partial tear of distal biceps tendon.
Median time from distal biceps tendon tear trauma to surgery was in complete tears group (40 patients) – 17 days and in partial tears group (22 patients) was 162 days.
This study has several limitations. The retrospective nature of this review resulted in the exclusion of patients who did not have appropriate documentation in the electronic medical record. However, the senior author began to prospectively collect these data early in the series. Patients in our study almost exclusively underwent a 2-incision transosseus fixation technique. An intact lacertus fibrosis may also confuse the examiner, highlighting the importance of actually “hooking” the tendon rather than simply palpating for a tendon in the antecubital fossa. The contralateral “normal” elbow should always be tested for comparison.
The hook test/resisted hook test have been proven that are useful tools for the quick and definitive diagnosis of distal biceps tendon ruptures, with specificity (100%) and sensivity (100%) higher than MRI.
We developed Algorithm that can guide clinical to diagnosing primary distal biceps tendon tears using hook and resisted hook tests.
To avoid misunderstandings, the reader must pay close attention to our definitions. Biceps avulsions were defined as complete if there were no tissues in continuity between the end of the biceps tendon and the radial tuberosity, such that the tendon could be retrieved from the wound without surgical release of tissues. Thus, if any surgical release was required to retrieve the tendon from the wound, we did not consider the avulsion to be complete. Devereaux and ElMar- reported 100% specificity and sensitivity for the hook test to detect 30 acute biceps avulsions but reported 8 false negatives in 18 chronic avulsions. Unfortunately, they did not use the same definition for complete avulsions as we originally reported. They stated that “the presence of a pseudo-tendon, often seen in chronic presentations, can also provide a ‘hookable’ cord and be mistaken for an intact tendon.” Such a pseudotendon has to be surgically released to retrieve the tendon, and therefore, we would have defined those as partial, not complete, tears, and thus, they would not have been false positives according to the original definition. However, it is not the terminology, but the correct application of the definitions of any given clinical test, that matters in reporting the hook test. To this end, the replacement of our 2 original terms (normal and abnormal) with the 3 terms proposed herein (intact, abnormal, and absent) should hopefully avoid such confusion.
In conclusion, our results would suggest that the resisted hook test is very useful tool to diagnose both complete and partial tears of primary distal biceps tendon ruptures. We developed Algorithm that can guide clinical to diagnosing primary distal biceps tendon tears using hook and resisted hook tests. Hookable and not painful hook test suggest INTACT distal biceps tendon. An ABSENT resisted hook test indicates that it is complete distal biceps tendon rupture. ABNORMAL (Painful) hook test is indication of partial tears. However if examiner perform hook test that is unhookable and afterwards perform resisted hook test which is hookable that strongly indicates partial tear of distal biceps tendon.
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