In contrast to the well-known Charcot neuroarthropathy (CN) of the foot, CN of the knee is hardly recognized. In a literature search, we only found five articles on total knee arthroplasty for Charcot joints (1–5). We did not find a single article dealing with alternative treatment options or the general clinical course of this disease.
We started our study because we saw two young patients with CN of knee within 2 months in our clinic. We reviewed all patients’ reports who had been treated in our clinic for CN of the foot (N = 281) from 1998 to 2010. Written consent was obtained as required, and all demands of the Declaration of Helsinki were fulfilled.
We found three patients with CN of the knee (all female; patient A: 25 years old, type 1 diabetes for 10 years, HbA1c was 11.6% [103 mmol/mol]; patient B: 26 years old, type 1 diabetes for 16 years, HbA1c 9.8% [84 mmol/mol]; patient C: 30 years old, type 1 diabetes for 13 years, HbA1c 9.1% [76 mmol/mol]). All had multiple complications of the diabetes, including severe polyneuropathy of the affected joints. All three had swelling, loss of strength, instability of the affected joints without trauma, and severe paresthesia without pain of the knee.
Two patients died before the age of 36 years. In two cases, total knee arthroplasty in other hospitals had failed through dislocation of the prosthesis after progression of bone loss. In one case, open reduction of the tibial head using a locking screw plate had failed. After transfer to our clinic, we stabilized the knee by applying a Hoffmann-II external fixator.
Consistent immobilization and initial offloading in a cast followed by a knee-ankle-foot orthosis stopped the process of joint destruction and led to remineralization in all cases, as seen in CN of the foot.
The same clinical course familiar to us from CN of the foot was seen in all three patients: painless swelling, reddening, and instability, combined with massive destruction of bone and joints were shown in the acute stage (Eichenholtz stage I), followed by decrease of clinical signs and reintegration of bone after immobilization (Eichenholtz stage II, coalescence), leading to Eichenholtz stage III (reconstruction) with remineralization and stabilization (Fig. 1). All of the patients were admitted for CN of the foot, and the diagnosis of CN of the knee was made on first admission to our hospital, even though they had seen multiple physicians. For this reason, we assume there could be a large number of patients with undiagnosed CN of the knee. More studies are needed in this field.
CN of the knee. Note the massive irregular and pathologic destruction of the medial tibial head with loss of bone integrity. No clear borders can be seen, and there are irregular new osseous structures (similar to CN of the foot).
CN of the knee. Note the massive irregular and pathologic destruction of the medial tibial head with loss of bone integrity. No clear borders can be seen, and there are irregular new osseous structures (similar to CN of the foot).
Patients with diabetes who present with instability, swelling, and/or paresthesia of the knee should be immediately examined for polyneuropathy and CN of the knee. The clinical course of CN is the same in the knee as in the foot, and corresponding treatment plans seem to be effective. This treatment schedule could be a valuable alternative to knee arthroplasty, which seems to be risky.
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Duality of Interest. No potential conflicts of interest relevant to this article were reported.
Author Contributions. U.I. initiated the study and wrote the draft of the manuscript. J.v.N., K.P., and T.M. revised and edited the manuscript. C.D. interviewed patients and searched the data and literature. H.H.W. co-initiated the study, examined patients, and revised the manuscript. U.I. is the guarantor of this work and, as such, had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
