Ileopsoas and rectus femoris need additional force to flex the striaght leg because the distal lever arm is longer. This overloads the prosthesis, especially the bone/prosthesis interface. This is very important for uncemented stems in the early postoperative period (before osteointegration occurs). I think the SLR should be avoided the first 3 postoperative months. Later it could be disregarded.

Here in America, that is not a precaution.  The usual precautions are no flexion past 90 degrees, no abduction, no internal rotation.  This is just for posterior approach total hip replacements.  It is possible that uncemented stems as Dr. Tanchev noted are no longer used in America.

Dear Dr. Hui, 

I am surprised to hear that uncemented stems are no longer used in America. Is it really so or I have misunderstood your note ? As far as the posterior approach is concerned, you are right in regard of avoiding extreme flexion and internal rotation. However, in my opinion adduction is more dangerous than abduction for a possible dislocation. 

Thank you both for your prompt responses.

Dr Tanchev, I am interested in learning more about the effect of the hip flexors on the bone / prosthesis interface. I would imagine that the force on weight bearing is much greater than the force occuring during SLR, but that is a compressive force. Is the concern that hip flexors are generating a shearing force?

Dr. Schmidt,

You are absolutely right that the compressive force on weight bearing is much greater, and that is why , in my opinion, early removal of walking aids for uncemented stems is not recommendable before the 3rd postoperative month. 

As far as the SLR is concerned, please, keep in mind that the ileopsoas muscle is not only hip flexor but external rotator as well. So shearing or torque forces are generated on bone/prosthesis interface more in straight leg than in flexed knee.  

Dear Dr. David Schmidt,

I see no reason to avoid the SLR, not exceeding 90 degrees and with the hip in neutral rotation. We use the SLR in the rehabilitation of patients from the early stages of post operative without adverse effects.

Dr. Stieven, 

Do you recommend the SLR also in uncemented stems ? 

May I humbly make one point. SLR (in lying) is not a functional movement, and should not be used. It makes more sense to do a PNF pattern combining hip flexion/ext. rotn for eg. in standing. With gravity being eliminated, there's much less pressure on the hip area, avoiding  overloading the prosthesis, especially the bone/prosthesis interface..

The full extension of  the hip is achieved by gradual physiotherapy within 3 months in normal cases. Over-extension or any other movement of the hip against pain has to be avoided (cemented and cementless). This would provoke also ossifications.  Further the surgical approach has to be watched. in ventral approach overextension and external rotation have to be avoided in the first 3 months, in dorsal approach inner rotation and adduction have to be avoided.

Hi David

I am unaware of any directly relevant research. A colleague recently went looking and found none, as I am sure you have done before posing the question.

My question is why would you ask someone to do a SLR at all, let alone post THR?

Yonatan hit the nail on the head - it is a non functional skill / ability / capacity. The only utility it offers is as a stress test. A bit like touching the toes for a LBP patient. Good stress test, appalling exercise.

Yes, lots of people are asked to do it with no apparent adverse consequence, but is there any evidence to show both the lack of negative impact AND the existence of positive impact of inclusion of SLR post THR (or any other time) ??

Perhaps hip flexors are inhibited post op, and maybe are weak pre op due to the usually) long standing pain issues around the hip. Good clinical practice would therefore be to provide a graded exercise program commencing with unloaded exercises (as per Yonatan and other methods). A SLR is probably the most stressful exercise to implement, and therefore not good clinical reasoning if the target is inhibition, pain and or weakness.

I believe the use of SLR has occurred because Orthopedic surgeons wanted to test people out post op. A SLR is certainly a good test if you want to stress someones hip flexion and lumbo-pelvic stability capacities. I think they actually just want to see if the patients quads are working, and a SLR is a quick and dirty method as the patient is usually supine in bed when the surgeon visits (and you don't have to touch the patient).

How Physiotherapists have taken the SLR into their protocols is beyond my comprehension.

In short, it does not pass the "So what?" test.

Cheers

Dear Dr. Lester, 

I agree with your opinion regarding the SLR test. This is a stress exercise and there is no sense to do it. 

I only disagree with you as far as the SLR (in the sense discussed) could be used to see if the quads work. Rectus femoris is the only part of quadriceps femoris that has its insertion proximally of the hip joint. 

Thanks Dr Tanchev.

I was not very clear.

The assumption is that to do an effective SLR and maintain full knee extension then the quads  other than rectus femoris are probably working well enough to make the surgeon confident there has been no neural injury, and that the patient is able to generate a decent contraction despite post op pain etc. They are not testing the hip specifically. 

I believe that many people then extrapolate that if that is a movement the surgeon wants to see then it must be a good movement to do.

Cheers

I try to understand, that you mean with the SLR that still on the operation table you perform a full extension of the hip joint; maybe overextension?

With this you may provoke not only small flexor-muscle-damages but also ischiadicus-nerve damage. It needs slow and steady physiotherapy, to decrease the former existing extension-deficit due to arthrosis.

Hi Dietrich.

No, I mean when the surgeon is doing their post-operative assessment of the patient at the bedside  in the ward situation. Usually in the days post op, not the same day.

My main point is that there is only damage or no benefit to be gained by SLR post THR. I am then offering an opinion as to why it is still performed in some post op protocols.

David, thank you for claryfying my misunderstanding.your are right!

Hi David

In our experience, raise the leg with hip extended, abducted and forcefully internal rotation loss of articular coaptation. So maneuvers are to be avoided.

Hi Dartl,

Please, tell me how would the patient raise the leg with hip extended in the supine position?  Probably, you mean flexing the hip. Moreover, independently from the approach used,  abducted hip is more stable than adducted hip. Do you mean adducted hip ? 

Of Corse...adducted HIP

Our postoperative protocol does not include hip flexion with knee extension

I would reason, that it is better (more functional) to do a standing SLR flexion exercise rather than in the supine position.  The flexion of the hip in standing would be more similar to the movement of the leg during gait. 

I agree and would not recommend SLR because any compact work is not suitable in early  stage and it effects in healing process,so low grad in standing SLR is ok to minimize compact forces between the joint.

                                                            Muzafar Hussain