Hi everyone, and I'd like to thank Anna and the Chairman of this session for the invitation to participate in today's program. I'm Tony Andrad and I'm President of ISHA, the Hip Preservation Society, and my task today is to talk to you about rotational malalignment and hip pain. These are my disclosures. When we talk about hip pain, we're really talking about hip impingement leading onto hip pain. And of course, everybody's familiar with femoral acetabular impingement, where there's an abutment of the anterior femoral head-neck junction against the anterior aspect of the acetabular rim or the labrum. And FAI is easy to recognize when we can see a CAM or a pincer lesion on radiographs, and we're really talking about the sphericity of the femoral head and the coverage from the acetabulum. And so if we look at an AP radiograph and we spot this pistol grip deformity, as we can see on the left, that's clearly a sign of FAI. If we look at the cross-table lateral and measure the alpha angle, and if we see that the alpha angle is greater than 55, then we can presume that to be abnormal and again associated with femoral acetabular impingement. But perhaps a more subtle deformity would be a sort of a reduced anterior offset ratio, where we're getting this thickening of the femoral neck anteriorly, and that can then lead on to impingement as well. But can FAI exist when radiographs appear normal? Well, in order to answer this, we first need to consider the range of motion of the hip. And when we're assessing the range of motion, we can ascribe certain normal ranges for each of the different movements from the hip joint. But it's important to remember that rotational abnormalities of the lower limbs will affect the range of motion. So here we can see in B where persistent femoral anteversion is associated with reduced external rotation of the hip, and in C where femoral retroversion is associated with reduced internal rotation. And again, we can see this on this prone examination, where the picture on the left, we can see external rotation, picture on the right, you can see it's reduced internal rotation. So you get that block at that particular point in the arc of movement. So it is important to assess rotational profile, and we do this with CT. And for the femur, we have three slices through the femur, as shown on the left, so that we can measure the femoral version. And for the acetabulum, we look at cranial and central acetabular version. But I would put it to you that it's important not to forget tibial rotation when assessing the lower limbs, and I'll come back to why this is so important later. But we can show you here now that the yellow line is showing a corrected left side, whereas on the right side, we can see the lower limb is internally rotated, so the patella is squinting inwards. And even with that, we can still see the foot is externally rotated. So the actual rotational deformity would be much greater than they would appear on this particular photograph. This was really brought to our attention in the current concepts review by Tanis et al. in December 1999, where they looked at compensatory tibial torsional deformities in both internal and external tibial torsion. And they looked at the normal femoral and acetabular antiversion and graded them according to the deformity. And they also looked at the McKibbin instability index, which was the sum of the angles of femoral and acetabular antiversion, and with a value of 60 is associated with severe instability, and a value of less than 20 is associated with altered rotation and resultant osteoarthritis. So why is this important? Well, Brian Kelly and his group have shown us that the post-operative improvements in a patient with relative femoral retroversion were still clinically important, but of significantly smaller magnitude than those in more normal version groups. They didn't find any associations between the McKibbin index and any patient reported outcomes. Lurch and his group in Bern looked at the prevalence of femoral and acetabular version abnormalities in patients with symptomatic hip disease. And they gave us this very useful table where we can see that normal version only occurred in 48 percent of their patient group, whereas normal acetabular version occurred in 70 percent of their group. I would draw your attention to this group in the bottom right hand corner, where four percent of their group had both decreased femoral and decreased acetabular version, so combined retroversion of the hip. They concluded that the prevalence of severely decreased and increased femoral version is particularly high in symptomatic hips, where no obvious pathomorphology can be found on conventional radiographs. So normal radiographs still having impingement, but here because of malrotation, and 17 percent of their group had severe femoral malversion. Now we in Reading and London looked at that particular group of combined femoral and acetabular retroversion, and as we already said it's about four percent of cases, and these two tertiary referral units dealt with these cases differently. So in one unit we carried out an anteverting proximal femoral osteotomy, and in the other an anteverting periacetabular osteotomy, and so we were comparing the two and comparing them to an FAI cohort with normal version undergoing arthroscopic FAI treatment. There were six patients in each group, and as I said these patients are quite rare. We followed them up for 24 months. We measured their acetabular version by the method described by Gemali et al, and measured the femoral version by the method described by Murphy et al, and this is our data, and what we can see is the McKibbin index is obviously very low, and in some cases with negative values showing how retroverted they were, and we can see here a picture on the left of the acetabular, sorry the periacetabular osteotomy, and a picture on the right of the femoral osteotomy, a picture on the right of the femoral osteotomy, and these are our results, and we can see that there was no statistically significant difference in outcomes for the two groups, and all patients achieved union during the time frame of the study, and the PROMs were inferior in both of those groups to the benchmarking FAI group treated with hip arthroscopy, and this may be due to related persisting intra-articular pathology such as labral tears that had not yet been addressed. So we can see that relative femoral retroversions is associated with significantly worse outcome of FAI surgery than those in other version groups, and so we can recommend rotational profile assessment for all patients with symptomatic FAI. Interestingly, Lerch also looked at the prevalence and diagnostic accuracy of in-toeing and out-toeing of the foot for patients with abnormal femoral torsion and femorastabular impingement, and they were able to produce another table here looking at the tibial and femoral torsion in their group. They concluded that in-toeing can help to detect increased femoral torsion with a high specificity and high positive predictive value, but they concluded that increased femoral torsion can be missed due to the low sensitivity and high FNR of in-toeing. Now interestingly, we think they've perhaps missed an important point here. We in Reading again looked at 100 symptomatic hips in 79 patients and looked at the CT rotational profile assessments for these over a three-year study period. We looked at the femoral and tibial version and measured them in a similar way to the Lerch group. We divided them up into different hip morphologies and also looked at the femoral and tibial torsions, and actually for our group, 55% of our patients had abnormal tibial torsion, which is somewhat different to their group. Interestingly, 59% of the limbs with excessive tibial torsion had femoral malversion, and perhaps even more interestingly, 55% of those had increased femoral version. So the limbs with severely increased tibial torsion had a higher mean femoral version than those with moderately increased to normal tibial torsion, and this was statistically significant, and so we would suggest that tibial malrotation is actually the primary deformity and that the femoral antiversion is actually a compensatory deformity. But are derotation osteotomies of the tibia effective at improving hip and knee pain and function? This was another study that we carried out, and we looked at 30 patients who underwent a distal tibial derotation osteotomy, and this included 27 females, average age of 26 years, over a 21-month follow-up period, and for this group, the mean tibial torsion was 49 degrees, with a range of 41 to 63. Now, what I would bring to your attention is this concept of tibial torsion-induced hip impingement. So we can see in the picture on the left, we have a normal tibial torsion with a normal femoral antiversion. If we look at the picture in the middle, we can see external tibial torsion in a resting or slow walking position. But what I would draw your attention to is that as you increase your walking pace or go into running, your foot needs to rotate into a forward-pointing position, which then internally rotates the knee which then internally rotates the knee and the hip, and so this can then cause impingement anteriorly, and if you have femoral antiversion, then that can compensate for this functional hip impingement, which can then delay the time to presentation of symptoms. However, if you have femoral retrotorsion, this exaggerates the functional hip impingement, and so it can accelerate the time to presentation. And so what we've achieved is this algorithm where if you have hip pain secondary to malrotation-induced hip impingement, and if you have isolated tibial maltorsion, in other words, no femoral malrotation, and whether you have a camel pincer or whether you have a labral tear or not, if you carry out a distal tibial derotation osteotomy, you can actually achieve resolution of symptoms in the vast majority of patients, and if you don't, you can then go on to carry out a hip arthroscopy. If we look at the other group, so the tibial maltorsion with combined hip malversion, and whether you've got camel pincer as well or labral tear as well, then you can actually achieve a resolution of symptoms just by carrying out tibial derotation osteotomy in some of these patients. In others, you might then need to go on to carry out either a proximal femoral osteotomy or a PAO, which can then achieve resolution of symptoms, and if it doesn't, then you might still need to carry out a hip arthroscopy to achieve the resolution of symptoms. Now if we look at patients with normal tibial torsion, but they might have combined hip malversion with either camel pincer, then again you might need to consider either a femoral osteotomy or a PAO to achieve resolution of symptoms, and if not, you might then need to go on to carry out a hip arthroscopy. And in our 30 patient group, these are our functional outcomes, so you can see you get good functional outcomes from six months onwards, but it can take up to 18 months to achieve better functional outcomes still. So in terms of learning points, we would suggest you should always assess the rotational profile clinically. You should have a low threshold to obtain CT rotational profile assessments of the lower limbs, looking at the acetabulum, femur, and tibia, and that you might need to correct malrotation before you consider addressing any labral pathology. And please don't forget tibial rotation. Thank you very much for your attention.

rotational malalignment

hip pain

femoral acetabular impingement (FAI)

radiographs

rotational abnormalities