When a TKR is done, one of the elements/objectives of the procedure is to establish/restore Patellofemoral alignment, tracking, and stability once the Femorotibial portion of the procedure been done, i.e. correcting the alignment of this part of the joint, particularly when either excessive varus or valgus deformity exist preoperatively. This may require relaxing the tight tissues to the lateral side of the patella with a Lateral Reticular Release, and/or with tightening the tissues to the medial side (medial retinaculum and vastus medialis advancement or tightening). Sometimes this is easier said than done. Since most all TKR's are done from a medial side arthrotomy with incision of the medial retinaculum, which must be repaired during closure, any residual or resulting chronic "subluxation" of the Patella long term after the primary procedure is going to be to the lateral side. Medial subluxation in this situation would be rare, if at all. The question is what happened to result in the problem of chronic lateral subluxation of the patella post TKR. I say chronic because it is rare that it is identified in the early (acute) postoperative period. In the acute/early postoperative period, it is most likely to result from inadequate Patellofemoral realignment at the time of the procedure, or a disruption of the deep retinacular repair done at the time of closure (T81.32X _: Disruption of an internal (deep) operative/surgical wound, 7th Character most likely S for Sequela). Unfortunately this can happen. In the chronic situation (outside or beyond the Global time period), the underlying cause may not be identifiable. The previously referenced possibilities still exist, but may not be clearly identifiable as such. At this point you are left with "Chronic Lateral Patellar Subluxation" as a diagnosis, which really doesn't have a specific ICD-10 code. This goes to the Code Set of M22: Disorders of the Patella. There are several possibilities from this Set, none of which are specific. These include M22.2: Patellofemoral Disorder; M22.3: "Other" Derangement of the Patella; and M22.8: "Other" Disorders of the Patella. Frankly, I am not sure what the difference is between a "Derangement" and a "Disorder." From my perspective, they are one in the same. However, since the problem is the position of the Patella in relation to the Femur, I would go with M22.2 _: Patellofemoral Disorder. To this I would add a code for the fact that this is a (chronic) postoperative complication of an internal joint prosthesis (TKR), namely T84.02 _ _: "Dislocation" of joint Prosthesis, which would include "Subluxation." This is in effect a chronic "Maltracking" and/or "Malalignment" process, which I consider essentially to be the same thing, rather than an "Instability" problem. This is confusing semantics in Orthopedic terminology/vernacular, but does have some relevance to this discussion, particularly in a chronic situation. This is a 7 Character code, with the 6th for laterality (2: right, 3: left), and the 7th of A, D, or S. Since this is the unfortunate consequence of an operative procedure, I think S would be the most appropriate if being treated by the same surgeon that did the initial procedure. Other, and far less specific, alternatives to T84.02 would be T84.09 _ _: "Other" Mechanical Complication of Joint Prosthesis, or/and T84.89 _ _: "Other" Specific Complication of Internal Orthopedic Prosthetic Devise.
As for the corrective surgery done, this would fall into the domain of "Proximal Realignment" procedures for this problem, for which I would recommend 27422: Reconstruction for Dislocation/Subluxation with Extensor Realignment, which would include (vastus medialis) muscle advancement, "capsular imbrication", and/or soft tissue release (i.e. Lateral Reticular Release, which he apparently did not do).
I hope this helps you (and others). I am sorry for the lengthy and complex/technical answer to your question, but it is not as simple as it would sound.
Respectfully submitted, Alan Pechacek, M.D.
icd10orthocoder.com
