PELVIC INSTABILITY

TABLE 1. GLUTEUS MAXIMUS – CLINICAL SUMMARY Athlete presents with:

Tight/painful hamstrings or lumbar paraspinals

Tight/painful adductor magnus

Excessively tight latissimus dorsi (remembering that dominant arm will often be slightly less flexible than non-dominant)

TABLE 2. GLUTEUS MEDIUS – CLINICAL SUMMARY Athlete presents with:

Swagger or pendulum gait Tight quadratus lumborum

Tight piriformis Tight ITB

What can it imply? Likely finding

Faulty extensor chain: muscles acting beyond Gmax weakness or their normal role

delayed timing

Faulty hip extension pattern: adductor Gmax function magnus increasing its contribution Faulty posterior oblique sling

decreased on same side Gmax function decreased on opposite side

What can it imply? Faulty stance phase of gait

Difficulty orientating the trunk vertically over the pelvis in gait, requiring overuse of lateral trunk muscles

Faulty pelvic control in weight bearing in coronal plane Faulty hip abduction or hip flexion strategy

the mechanics of the structures around it, and this can manifest as anterior knee pain, sacroliliac problems, nerve compres- sion around the head of fibula and even ankle pain.

It is surprisingly common to see patients, even athletes, who have difficulty in maintaining a level pelvis and a relaxed vertical trunk in single leg stance. Many use excessive global muscular activity to compensate for loss of this deep postural stabiliser function, and this can be observed in excessive ankle and foot activity, fixing of the ribs with the obliques, pinning down of the sternum with rectus abdominis, excessive scapular retraction and deepening of anterior pelvic tilt.

As long as the load on the musculoskele- tal system can be met by the individual’s ability to compensate, they may be able to escape injury. However, long-term inef- ficiency can take its toll, and in the case of athletes, the loading requirements of training can eventually exceed their abili- ty to compensate, causing them to break down.

Piriformis is the other common responder to Gmed weakness. It orginates on the anteri- or surface of the sacrum and passes across the sacroiliac joint and through the greater sciatic foramen to insert onto the greater trochanter. Piriformis has a rotatory effect on the femur, but can also take a weak abduction role. If Gmed is not functioning well, piriformis steps in to try and assist in

www.sportex.net

lateral pelvic stabilisation. Unfortunately it is not well suited to the repetitive increase in load, and like ITB, will cause a variety of problems in the joints around it. Although piriformis is often acutely tender when directly palpated, it is not usually a patient’s presenting complaint. By altering joint mechanics in the area it is more like- ly to cause sacroiliac joint pain, sciatic pain or lower back pain.

Gmed’s fundamental pelvic stabilisation role in weight-bearing influences joint position and movement efficiency throughout the kinetic chain, and weak- ness can be associated with a variety of painful presentations including the knee, sacroiliac joints and lower back.

It should be remembered that these are broad guidelines, and that pain presenta- tions and biomechanical dysfunctions are the result of

interplay of factors.

Nevertheless, these patterns of tight- ness/overactivity and weakness/underac- tivity involving Gmax and Gmed occur fre- quently, and with simple tests (see Box 1) you may gain some insight into the mech- anisms behind intractable or recurring problems.

THE AUTHOR

Joanne Elphinston B.Phty MA MCSP is an Australian physiotherapist, lecturer, author and performance consultant. She lectures internationally on applied stability con- cepts for performance and rehabilitation, and provides consultancy on the subject for national sporting bodies in sports including golf, tennis, kayak, rowing, track, swim- ming and badminton.

Common finding Weak Gmed Weak Gmed

Weak Gmed Weak Gmed, weak psoas

References 1. Hintermeister RA, O'Connor DD et al. Muscle activity in wedge, parallel, and giant slalom skiing. Medicine and Science in Sports and Exercise 1997;29(4):548-53 2. Li L and Caldwell G. Muscle coordination in cycling: effect of surface incline and posture. Journal of Applied Physiology 1998;85(3): 927-934 3. Mascal CL, Landel R, Powers C. Management of patellofemoral pain targeting hip, pelvis, and trunk muscle function: 2 case reports. Journal of Orthopaedic Sports Physical Therapy 2003;Nov;33(11):647-660 4. Van Wingerden JP, Vleeming A, Buyruk HM, Raissadat K. Stabilization of the sacroiliac joint in vivo: verification of muscular contri- bution to force closure of

the pelvis.

European Spine Journal 2004;May;13 (3):199-205 5. Vleeming A, Pool-Goudzwaard AL, Stoeckart R, van Wingerden JP, Snijders CJ. The posteri- or layer of the thoracolumbar fascia. Its func- tion in load transfer from spine to legs. Spine 1995;Apr1;20(7):753-758 6. Hungerford B, Gilleard W, Hodges P. Evidence of altered lumbopelvic muscle recruitment in the presence of sacroiliac joint pain. Spine 2003;15;28(14):1593-600 7. Mottram S and Comerford M. Stability dys- function and low back pain. Journal of Orthopaedic Medicine 1998;21:13-18 8. Neptune RR, Zajac FE, Kautz SA. Muscle force redistributes segmental power for body progression during walking. Gait Posture 2004;Apr;19(2):194-205 9. Bullock-Saxton JE, Janda V, Bullock MI. The influence of ankle sprain injury on muscle activation during hip extension. International Journal of Sports Medicine 1994; Aug;15(6):330-334 10. Lee D and Vleeming A. Diagnostic Tools For The Impaired Pelvis. Lecture notes for the American Back Society Annual Meeting December 7-9, in Vancouver, Canada 2000.

15