- Question: Is it normal to expect this "alignment margin" in this type of surgery? Any statistics that says a broken femur is likely to remain slightly off after surgery?
Faye Loughenbury, Anthony McWilliams and their colleagues have conducted several studies that may in part answer your questions. I quote from "Hip surgeons and leg length inequality after primary hip replacement":
"89% of surgeons agreed that 15 mm of leg length inequality (LLI) after primary uncomplicated total hip replacement (THR) was always acceptable. 90% of surgeons felt that LLI more than 22.74 mm was never acceptable."
- Question: Is this something i could potentially never be able to correct either via exercising or possibly other kinds of medical intervention?
While you cannot correct the relative difference that the operated leg has towards the other, a heel lift with the specific - exact (!) - height offers a tolerable compensation. Current focus is on leg length inequalities not mattering much if lower than 1,5 cm or 1 cm or, at best, 5 mm. If all lower extremity joints are examined for sufficient support of range of movement (patients may ask their physiotherapists) contributing to a well compensated overall functional leg length (that includes slightly extension-limited knee joints you might not have noticed, or missing arch support on the side of the (previously) anatomically longer leg) - you should live a happy life after all. If you are very technical about your question, and should doctors recommend THR of the second hip, some counter-compensation may be achieved when well planned. It may also help to be aware that the average LLI/LLD of the general population is 5 mm. However, the sensation of "limping" may intensify if the naturally shorter leg has become even shorter or the longer even longer. Anybody should use a heel lift, for fun, and compare sides. Most people will notice "a funny feeling" only with the heel lift under one of the two legs, specifically, as compared to the lift under the other heel. (It also may help to know that, clinically, hip arthroplasty patients that have a referring pain from the spine (reacting to the hip via the mediation of the pelvis) are not too seldom - at the same time there seems to be evidence that this would not matter - circumstances are unique, that is why stackexchange is serious about avoiding personal medical advice).
- Could the difference in length be more than 5mm, and they said that to sound "optimistic"?
A tough question, to me, because we cannot know what "they" really thought. Considering the cited statistics, a patient with 5 mm length difference after THR is lucky with a relatively small "off" value. However, since in the general population the left leg is longer than the shorter right leg, it may add up to a centimetre in your case. To my personal clinical experience - that will most likely sound blasphemic - every millimeter matters, even less than a tenth. If clinical collaborateurs learn to palpate the effect of marginal leg length on the joints of the spine in bilateral comparison and for several segments, they may easily reproduce the causes for my judgment to consider less than a tenth of a millimeter important. I believe that future direction of reasearch will head there - however, I experience disbelief in clinical partners whenever I tell them what I palpate there - you can hardly find any reference in the literature to such manual precision yet, also not in functional radiography or MRI. Given the likelyhood of pain overlooked in its functional genesis, it is very likely that doctors really think that patients should not have pain (while they may have) after THR, as we may also think that patients should accept a limp if they would not wear a heel lift or have their shoes prepared by a orthopedic shoe specialist, which can most certainly be a fantastic relief in having done (if as exact as is possible).
- Question: If the difference is real (and it feels like it could be, since i am still limping a bit) and i am never able to correct it in any way, what kind of side effects should i expect?
You'll see that my answers will repeat a little bit, but that should not matter much. If the patient made sure that his or her joints have no movement restrictions (knee joint extension in particular), checks if an arch support would be necessary and makes sure the person asked sees him/her as well walking as standing - that should correct quite a bit of limping, when also the correct (!) amount of the heel lift is found (for example, I use layers of different thicknesses of tape to add - subtract, on contralateral side - some necessary bits - sometimes, a single layer). If all shoes are lifted (a patient could place a lift in a sock, if he or she wouldn't want to avoid being "barefoot"), I would not expect major caveats. There may be individual things only an experienced examiner finds. At the same time, if a patient just gives in to leg length difference and does nothing about it - just goes limping - this amounts to asymmetric load transfer and greater asymmetric joint use all over the body than necessary, most importantly the (lumbar) spine, knees and (other) hip. We always try to establish a somewhat symmetrical movement - within its borders, deviations are alright, but if you ask clinicians, the definition of "deviation" can differ quite a bit. My suggestion would be to prevent unilateralization for the lumbar spine and neighboring joints of the hip with the help of an experienced manual therapist or doctor of osteopathic medicine having specifically stated experiences with leg length differences.
- Question: Should i double check with another doctor?
Most doctors would probably tell you that 5 mm is no big deal. If you read the survey responses gathered by Anthony McWilliams and his colleagues, some doctors think that double that amount is no big deal, and some think that even more is still acceptable. user8412 said that we deserve to be in control and provided appropriate information. Unfortunately the expertise about leg length differences has not yet enabled many clinicians to provide sufficient information, due to a rather growing evidence base. A physiotherapist with special training (there are orthopedic manual therapists, for example) or an informed osteopath might as well provide further help. Sometimes they work together with orthoticists. However, somebody should also entertain the difficult work to inform surgeons and orthopedists so that they might become sensitized for the fact that "millimeters" do matter - if, apparently, little - at least to stimulate new and open research questions. The patients and their therapy experiences may inform resarch - so patients theirselves, in their responses to and articulations of outcomes are most likely the very key for future patient experiences, also in the domain of leg length difference / inequality.
- Question: What are my options?
Only if the options referred to until here seem to leave open an essential gap, it might be beneficial to actually write to some of the doctors conducting resarch for the topic, offering your participation in trials and on the way get adequate "on the edge" diagnosis - many doctors with a hunch for this specific topic, as it is seldom enough, actually treat real patients :) ... however, as, for example, spine symptoms - "unspecific low back pain" - can be a consequence of THR, asymptomatic patients in matters of pain might just be fine with a general screening of a physiotherapist, orthoticist and/or orthopedist. It could very well be, that a specialist can only point to what part of a problem is explicity not falling in his or her domain.
While this can look like dry information, I hope it does not suck you into some mills of drifting into too much reflection but provide someone with a little hand of helping overview where needed.
