Homer Test: A New Test for Meniscal Damage Within the Knee

Case Report of a new clinical assessment tool of meniscal injury:

The Homer Test
By Ralph Simpson PT
Cohort 2 tDPT Program

July 12, 2011
University of Montana
Abstract

Purpose: The purpose of this case report was to investigate a meniscal assessment technique and its successful use in knee injury assessment.

Case Description: A 64 year old man injured his knee while skiing and sought assessment and rehabilitation advice from a physical therapist in a direct access private practice setting.  His history suggested intra-articular damage; a new examination technique (Homer test) was used to assess his injury.  Information provided by the Homer test helped direct care and advice for this patient. 

Outcomes: The client returned to his desired level of physical activity after the Homer test effectively assessed a meniscal lesion.  A mini-statistical analysis was performed on the examination results of 23 patient’s knees suspected of having meniscal damage.  The Homer test showed sensitivity at 85%, specificity at 63%, and accuracy at 70%.  Likelihood ratios indicated a small but important shift in probability.

Discussion: Current axially loaded meniscal tests are discussed and compared to the Homer test.  Possible anatomical mechanisms that contribute to the Homer test results are examined.

Key words: knee, meniscus, axial-loaded meniscal tests, clinical meniscal examination

Autonomous physical therapy practice requires honed assessment skills by the therapist to provide patients accurate assessment and prognosis while coordinating a plan of care or referral.¹  It is imperative the therapist moves accurately with assessment and treatment to help control costs and provide patients sound direction. 

Knee ligamentous and meniscal injuries have been shown to lead to earlier degenerative changes.2  Stein et al reported that a repaired meniscus will result in less degenerative change to a knee joint than a meniscectomy or even partial meniscectomy.3  If there is a chance to repair a meniscus, especially in a younger patient, then it’s important to investigate that option.  The longer a patient walks and exercises on a partial, mobile tear the greater the chance that the tear will progress and possibly reach a non-repairable level. Early assessment can be pivotal for the younger patient, and possibly for the very active older patient as well, to possibly aid in the prevention of accelerated degenerative changes.4

Knee injuries are often surgically treated and are more and more commonly seen by the physical therapist as a direct access visit before surgery or even physician examination.5  An estimated 3.7 million patients seek evaluation of knee injuries from primary care physicians annually and, of that, 9% have suspected meniscal injuries.6

MRI evaluation is considered to be the most widely used non-invasive test for meniscal injury evaluation, but it is also an expensive and potentially over-used assessment device.5,7,8  There is disagreement in the literature about the overall accuracy of an MRI to diagnose meniscal pathology with reports of 93% accuracy to 98%.9-13  However, Ben-Galim et al. showed a false positive rate of 65% for medial meniscus tears and 43% for lateral meniscus when compared to surgical findings.14  Additionally, Oei et al. and Laundre et al. have published MRI accuracies for finding lateral meniscus tears as low as 79%.15,16 Yet several studies have shown manual assessment and clinical evaluation to be of better diagnostic utility.8,17, 18

Although tests and measures are an integral part of any examination, a thorough subjective history can sometimes be more accurate than physical tests. This is especially true when it comes to meniscal injury.  Patient reported symptoms alone could have a predictive value of up to 70% to 80% and possibly even as high as 97%.19,20  It logically holds that physical tests in combination with a solid subjective examination will give consistently more accurate results than either one alone.  That holds for clustered physical tests; when a collection of established physical tests converge, accuracy improves.21, 22, 23  Physical therapists and/or physicians must have manual tools to accurately assess meniscal injuries to avoid unnecessary MRI examination.6 

The Apley’s grind test, McMurray test and joint line palpation as described by Hoppenfeld and Malanga are some of the more commonly used traditional tests in the evaluation of meniscal injury. 24,25  In a 2001 meta-analysis of assessment of meniscal injury, Apley’s compression, joint line tenderness, McMurray’s test, and joint effusion were found to be of “little value in clinical practice”.26  Fowler stated that the Apley’s tests “do not correlate well with meniscal pathology under any circumstances”.23  Tests that provide an axial load seem to be of better predictive value and have been called “critical” by Meserve et al as well as Kurosaka et al in reproducing pain with testing for meniscal injury.6, 27 

Three relatively new tests:  the Ege, the Thessaly, and the axially loaded pivot shift have much better reported specificity and sensitivity through axial loading.5,27,28  The Ege and the Thessaly require patient weight bearing, balance, mobility, and coordination to provide the axial load.28,5  It may be difficult for patients to relax thoroughly for proper application of the axially loaded pivot shift and significantly more training is necessary to properly administer this test than the Ege or Thessaly.  Patients with acute knee injuries or other co-morbidities have shown several guarding responses while performing or having axially-loaded tests performed on them.5,28   For example, single leg balance and twisting movements required while keeping a specific knee flexion angle often make the Thessaly test impossible to apply.  Because of the full weight-bearing status of the Thessaly and the Ege tests, they are not done during the first 4 weeks after injury due to pain associated with general trauma and not necessarily the meniscus.5  Akseki et al reported the Ege test may be confounded by existing patello-femoral joint disease and is not routinely performed on those with a loss of motion, age induced weakness, obesity, or pain.28  Therefore, when circumstances don’t allow for the use of current established axially-loaded meniscal tests another test of similar specificity and sensitivity and axial loading would be useful.

The purpose of this case study was to investigate the Homer test, a new knee assessment technique designed to test the integrity of the meniscus while incorporating axial loading, rotation, and shear.

Case Description

History

An athletic, 6’, 180 pound, 64 year old patient suffered a skiing injury to his left knee when he fell backward and maximally flexed his knee.  He felt more than heard a “pop” and experienced immediate pain in his knee that gradually subsided.  He skied for several more runs without undo pain or instability but with a low grade ache as described by the patient.  While there was no immediate swelling, significant swelling was present by the next morning making full flexion painfully limited.  He complained of pain with weight-bearing twisting motions during activities of daily living.  He denied any “giving way” episodes, “locking” of the knee or disruption of sleep patterns but stated his knee was much stiffer in the morning upon rising from bed.  Five days after the initial injury, using direct access, he sought the assessment and advice of a physical therapist.  Having never had a previous knee injury, the patient was concerned that he had an injury that would require surgery or rehabilitation.  He wanted to begin treatment that would enable him to pursue hiking and biking through the coming summer and to return to skiing the following season.

Systems Review:

Cardiovascular, integumentary, neurological, and gastrointestinal:  There were no significant cardiovascular, integumentary, neurological, and gastrointestinal findings upon initial examination.

Vital signs:  Vital signs were not noted at the time of initial examination.

Musculoskeletal:  The patient was observed ambulating into the clinic without any limping.  The left knee showed signs of acute inflammation: excessive warmth and swelling.  He showed no obvious pain or apprehension to movement of the joint in weight-bearing or non-weight bearing.  Although he had a history of episodic low back pain; he was currently without obvious symptoms and trunk movements were full without eliciting pain in his back or his leg.  Gross range of motion (ROM) of hip flexion, abduction, adduction, extension, internal rotation, and external rotation were within normal limits (WNL).  Gross motor strength of knee flexion, hip flexion, extension, and adduction were WNL (5/5) without pain.  Hip abduction and knee extension showed a slight weakness of 4/5 and 4+/5 respectively on the involved side and 5/5 on the uninvolved side.

Initial Clinical Impression:  The patient was suspected to have sustained an injury to either the meniscus or other inert structures of the knee.  Although his history of “falling backward” is consistent with skiing-induced anterior cruciate ligament (ACL) injury his lack of initial swelling, ability to continue to ski, and no history of buckling or “giving way” suggested his ligament structures were intact. 29,30  His knee ROM did not suggest a bucket handle-type meniscal tear as there was no locking and his motion was nearly full.25  Symptoms had been reproduced with skiing, deep squatting, and occasional weighted twisting movements (getting out of a car, for example).  More precise tests and measures were indicated by the systems review to assess ligamentous as well as meniscal structures.  Since he was 5 days post-injury, the Homer test was one of the tests chosen as it is sensitive to meniscal tears, particularly lateral meniscal tears and can be applied in the acute injury phase.31

  

Tests and Measures:

Palpation provoked medial and lateral joint line pain.  Mild crepitus at the patello-femoral joint with active extension was also noted.  Patellar facets were painful to palpation medially.  Swelling was noted via a ballottement test and milking tests.24  Prominent palpable posterior joint swelling was noted to be firm and was suggestive of a Baker’s cyst.  Knee passive range of motion (PROM) showed pain free full extension (0°) but terminal flexion with overpressure reproduced knee pain with a 15° loss of motion.  AROM was without pain 0° to 120° in a non-weight bearing supine position.  Ligament stress testing, as reported by Malanga et al (medial and lateral gapping at 0° and 30°, Lachman, and posterior drawer) were negative for pain or instability.25

Quadriceps contraction ability was measured via an inflatable air bladder behind the knee and showed a 22% loss of quad strength on the injured side vs. the non-injured side.

Special tests for meniscal involvement were performed with negative findings for meniscal involvement with McMurray’s, Apley’s, and the bounce home test.25  The patient was unable to perform Ege’s test to the required 90° of flexion due to pain at his anterior knee.28  Homer testing at 120° with internal tibial rotation reproduced his deep joint ache when the posterior shear was applied.  The Thessaly test at 20° with internal rotation also reproduced his pain.5

Clinical Impression

A clinical impression was formed of possible meniscal damage and probable chondromalacia with subsequent joint inflammation and swelling.  Ski injuries of the knee usually require ligament stress testing as these ligaments are often injured in skiing accidents.  In this patient’s case neither his history nor his special tests were consistent with ligament damage.  He did have swelling and via mecho-receptor inhibition his quadriceps would normally show rapid, albeit slight, strength loss.32  Painful patellar facets accompanied with extension crepitus are often present with articular defects associated with patellar chondromalacia.33  The patient’s anterior knee pain with attempts at 90° of flexion in weight-bearing were also consistent with patello-femoral pain. Therefore, patellar chondromalacia could not be ruled out as a cause of his symptomatic pain25.  Since his injury was one of hyper-flexion, his patellae would be driven deep into the trochlear groove possibly worsening or irritating a pre-existing articular condition.  Although his clustered signs for meniscal involvement did not present as an obvious suspected meniscal tear, this hyper-flexion history, lack of ligament involvement and positive Homer and Thessaly tests did suggest a probable meniscal involvement.

Intervention

The patient was instructed on initial care including a home exercise plan and inflammatory reduction/control techniques.  Those included periodic ice application (15 minutes per session and no more than 1 session per hour) and elevation with the hip and knee both at 90° flexion.  Hourly quad sets (50x per hour), once per day semi-reclined straight leg raises, side lying lateral leg raises (abductors), and side lying adductor leg raises (all at 3×20 reps) were begun.  He was instructed in the use of a stationary exercise bike in a spinning mode of 90 rpms with minimal resistance for up to 15 minutes two times daily without pain.  The seat post was adjusted to allow for approximately a 10° flexion angle at the bottom of the pedal stroke.  The patient was asked to refrain from skiing for at least one week.   

At a one week follow up, initial inflammatory changes had reduced: milking test showed minimal to no swelling; increased joint warmth remained as did the defined posterior swelling.  He continued to have pain with weight-bearing twisting motions but only when his knee was bent greater than approximately 45°.  Although he was improving and inflammatory signs were reducing, the patient remained concerned about the damage extent.  His Homer and Thessaly tests remained positive.  Upon further discussion he was referred to an orthopedic surgeon for consultation.  He continued his home program until his scheduled physician appointment.  The physician did not report any manual assessment findings but did order an MRI evaluation.

Upon MRI evaluation, the radiologist interpreted a torn anterior horn of the lateral meniscus and noted significant chondral loss at the patello-femoral joint and trochlear groove.  The orthopedic surgeon indicated that this was a stable, peripheral tear.  This physician recommended continued conservative care and progressive rehabilitative exercise rather than arthroscopic intervention.  Over the next 3 weeks, the patient progressed to pain free vigorous biking and weight training and did not return to skiing for the rest of the season.  Weight-bearing twisting activities had become pain free by week 6 post-injury.  He progressed to spring time hiking and biking.

Homer Test Description

The Homer test uses 4 knee positions with the patient in prone for testing and is designed to stress the possibly damaged meniscus or anatomical structures that have attachments to the meniscus.  Combinations of forces are manually applied to the knee in a fashion less likely to aggravate other structures.  Compression and shear are added to each of these positions in an attempt to reproduce a patient’s symptomatic pain.  Specifically, the test is performed as follows:  A pad or folded towel is placed under the distal thigh just superior to the patella to avoid any undo patellar compression and subsequent pain.  A pillow may be added under the pelvis if the patient complains of low back pain in the prone position.  The knee is passively flexed to approximately 30° flexion, external tibial rotation (ETR) is passively applied through the foot, long axis tibial compression is added through the foot/ankle then an anteriorly directed shear is applied, (see Figure 1).  The sequence is repeated with internal tibial rotation (ITR), (see Figure 2).  Care is taken to insure relaxed hamstrings as the shear force is applied to the posterior tibial plateau.  Pressure on the superficial peroneal nerve and the fibular head are avoided.  This same sequence is then performed with the knee flexed to approximately 120° (or the amount allowed by the joint).  The shear is now directed posteriorly though the superior tibial plateau, (see Figures 3, 4).  Positive findings reproduce the patient’s pain symptom.

             

most1                     Most2
Figure 1.                                                            Figure 2.

30º external tibial rotation (ETR)                       30º internal tibial rotation (ITR)

  

most3                      most4
Figure 3.                                                            Figure 4.

120º external tibial rotation (ETR)                     120º internal tibial rotation (ITR)

The Homer test has not been reported in current literature.  There are no established statistics on sensitivity, specificity, or accuracy and as such a mini-study was done to provide these statistics.

Between January, 2011 and May, 2011 comparative data on the Homer test was collected by 2 orthopedic surgeons and one independent private-practice physical therapist.  All physicians were instructed in the Homer test theory and step by step instructions of the Homer test.  The physicians demonstrated the test successfully on a test subject. The findings of their results of the Homer Test on 23 patients are presented as compared to MRI and/or arthroscopic evaluation and contrasted to McMurray’s, Apley’s, joint line, and axial-loaded tests for sensitivity, specificity, and accuracy (see Table 2). 

Results

The formula for calculating accuracy, sensitivity, and specificity is presented in Table 1(adapted from Akseki et al. 28).  True positive (POS) and true (NEG) were determined either by MRI or arthroscopic evaluation.

MOST table 1

The clinical practice guidelines published by Logerstedt et al. provide the most recent inclusive summary of statistical analysis of several of the tests for possible meniscal involvement.34  A summary of this work, from multiple studies, was used to present specificity, sensitivity, and accuracy of these tests.6,8,17,19,21,23,26,27  High sensitivity scores mean a test can be used for excluding a condition when the test is negative.  High specificity means a test can be used for including a condition when the test is positive.35

Likelihood ratio (LR) is a measure of how likely a given test result would be expected in a patient with a target disorder and because tests can be positive or negative, LR comes in both forms.  A positive LR (+LR) indicates the level of certainty that a patient with a positive test does indeed have the condition.  A negative LR (-LR) indicates the degree of certainty that a patient with a negative finding truly does not have the condition.37  Positive and negative LRs were calculated for the Homer test and these were compared to LRs of other axially loaded tests.  Positive LR was calculated by dividing sensitivity by 1-specificity.  Negative LR was calculated by using 1-sensitivity divided by specificity.  Table 3 provides interpretation of those ratios while Table 4 provides a comparison of various tests’ LRs.

MOST table 2

MOST table3-4

Discussion

The purpose of this case report was to introduce and investigate a test for meniscal injury.  The specified positions of the test (30° and 120° of flexion) are used for distinct reasons.  Maximal tibial internal and external rotation occur at 20° to 40° of flexion.37  To stress the menisci and their various attachments to the tibia and soft tissues maximal tibial excursion is desired.37, 38  Relatively deep flexion of approximately 120° flexion places enhanced if not exclusive compressive stress to the posterior horns of both menisci.39,40  The addition of manual axial compression is thought to mimic weight bearing conditions.27  Compression at 20° flexion with dynamic weight bearing rotation during the Thessaly test may squeeze apart the fragments of a torn meniscus and elicit pain via nocioceptors.5  Kurosaka stated similar thoughts in his discussion of the axially-loaded pivot shift test, but the compressive load used in this non-weight bearing test is much less than weight bearing.27  As a non-weight bearing test, the Homer uses axial compression and rotation but shear is also added to provide the provocation sufficient to reproduce a patient’s pain.  The patient in this case report had a negative response for pain or clunking with the traditional meniscal tests of McMurray’s, Apley’s, and bounce home.  Because of confounding patello-femoral pain, the newer Ege’s test could not be used as the flexion required elicited anterior knee pain.  The patient’s initial assessment was at 5 days post injury.  The authors of both the Ege and the Thessaly tests, however, do not recommend that their tests be used up to 4 weeks post injury due to confounding signs from other acutely damaged joint structures.  Since the 20º Thessaly reproduced knee pain at 5 days post injury, its result is suspect based on the author’s recommendations.  Another test was needed to corroborate findings.  The Homer test can be administered acutely since the 3 forces can be applied in a controlled, graded fashion and are much less than weight bearing.  In this case, the Homer test was aptly applied and provided information useful in directing care and patient advice.  Most meniscal injuries seem to occur from a combination of torsion and axial loading while weight bearing.41  The applied shear (in combination with compression and rotation) is thought to add the additional load necessary to accommodate for the lack of weight bearing force; whether it is anteriorly or posteriorly directed.  Anatomically, the menisci attach to the anterior cruciate as well as the patello-meniscal ligaments (thickenings of the anterior capsule).41  Therefore, anterior shear would stress these structures which in turn may tension a torn meniscus. 

The number of subjects in this “mini” study is admittedly too low to draw strong conclusions.  However, gathered data on specificity, sensitivity, accuracy, and likelihood ratios place this test at similar strength with most other tests for meniscal involvement.  In fact, the generated LR’s place all the tests (except the 20° Thessaly) within the same level “that generate small but sometimes important shifts in probability.”36  The Homer test showed high sensitivity but the low “n” for lateral meniscal (LM) injuries precluded separating medial from lateral meniscal involvement in statistical analysis. 

Although only 3 of the test patients had LM injuries, all 3 had positive findings by the Homer test.  Yet 2 (confirmed by arthroscopy and one by MRI) had negative McMurray’s, negative Apley’s, and negative joint line tenderness.  However small the number of cases were, there is sound anatomical reasoning for LM sensitivity to remain high and for specificity to improve when more data is collected in a larger study.  Posterior shear force stresses small ligaments in the posterior knee collectively called the menisco-femoral ligaments.42  The menisco-femoral ligaments (MFL) have two separate bundles:  the anterior menisco-femoral ligament (aMFL) of Humphrey and the posterior menisco-femoral ligament (pMFL) of Wrisberg.43  The aMFL is anterior to the posterior cruciate ligament (PCL) while the pMFL is posterior; both are essentially parallel to the PCL.  These small ligaments attach to the posterior horn of the lateral meniscus from an intercondylar area of the femur and are thought to be responsible for anchoring the lateral meniscus and for pulling the lateral meniscus posteriorly with knee flexion.44  Just as posterior shear stresses the PCL it also places stress upon the MFL complex.42  Additionally, tibial rotation has been shown to alter tension to the MFL complex.45  It is possible that posterior shearing, in combination with the meniscal compression from flexion, axial loading, and tibial rotation applies enhanced tension into the lateral meniscus via this complex.  Since the horns and outer third of the menisci as well as the MFL are richly supplied with nocioceptors, this MFL tension may lead to a reproduction of pain and symptoms that are more noticeable in the lateral meniscus than the medial meniscus.46  This becomes especially important since tears of the posterior horn of the lateral meniscus are the most commonly missed with MRI evaluation.16  Diagnosing lateral meniscus tears has historically been more difficult than medial meniscus tears.28 

Grading for the Homer test is fairly broad and is based on reproducing the patient’s pain.  It is conceivable this pain is derived from the various tibial-meniscal attachments, ligaments, MFL, or the meniscus itself since all those structures have nocioceptive ability.46  Several authors postulate that external tibial rotation (ETR) stress will accentuate medial meniscus stress while internal tibial rotation (ITR) stress will stress the lateral meniscus more specifically.46, 39  Yet as reported by Chivers et al, other researchers state ITR in combination with flexion can create a medial meniscus tear.41  There seems to be disagreement in the literature whether ETR or ITR can be accurately applied to either meniscus injury with a high level of certainty.  In this small group there was no difference in the ability of ETR or ITR to precisely identify the damaged meniscus at 120° or 30° of flexion.

Summary

This case report presented an axially-loaded meniscal evaluation technique that has advantages over existing axially loaded tests as it can be effectively applied to the acutely or sub-acutely injured patient.  The Homer test’s application is not affected by age, weakness, balance, obesity, neurological involvement, or patello-femoral pain as are the other weight-bearing tests.  It is simpler and safer to apply than the axially loaded pivot shift test and it has comparable statistical evidence of efficacy to all tests except the Thessaly at 20°.  Its advantage is apparent in situations where the Thessaly cannot be easily applied.  This case report showed the Homer’s effective use in a situation when all but one of the clustered meniscal tests were negative and one weight bearing test was eliminated due to co-morbidity of patello-femoral arthralgia.  Statistics reported are admittedly weak as the number of patients was low (23) and the gold standard of arthroscopic examination was only applied to 6 of the 23.  One physician reported difficulty in administering the test as well.  The combination of forces delivered by the clinician (axial loading, rotation, and shear) was felt by this surgeon to be difficult to coordinate.  Future research on reliability and blinded assessment would improve statistical strength as would a larger number of patients.

The addition of all three components: axial loading, rotation, and shear seem to be important in making the Homer a test that may prove to be one of the essential tests in the manual assessment of meniscal and particularly lateral meniscal injuries.

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