As orthopaedic surgeons in training, we were all taught about chondrolysis as it relates to the pediatric hip1. Unfortunately, another type of chondrolysis has surfaced in recent years with increased frequency. Most notably, this has been described in the shoulder2. Although exact trigger events have not been fully determined, the cases appear to be associated with primarily arthroscopic procedures, variable use of heat probe electrical devices, intra-articular pain pumps for postoperative pain control, prominent hardware, and infections1,2.
The article by Noyes et al. brings to our attention a series of cases of chondrolysis of the knee that were presumed to be due to intra-articular pain pump usage and constant infusion of bupivacaine over a minimum of forty-eight hours after a surgical procedure. The authors report on twenty-one patients with a mean age of twenty-three years. As has been reported in studies of chondrolysis in the shoulder, this condition is unfortunately common in the young patient, who one would presume, for the most part, to have normal articular cartilage at the time of the index operation. In the series by Noyes et al., increasing pain developed primarily in the first year after the use of the pain pump, which again is similar to what has been reported in the shoulder. Interestingly, in the current study, the meniscus seemed to be relatively resistant to the effects of the bupivacaine, which were so devastating to the articular cartilage.
We are currently going through a transformation in orthopaedic literature, and levels of evidence have become more front and center in the evaluation of a particular study’s importance. To that end, the study by Noyes et al. is only Level IV. Unfortunately, that is also true for most of the shoulder chondrolysis cases that have been accumulated to date1. Noyes et al. did not report how many patients who were managed with use of pain pumps did not develop chondrolysis. We do not know if there are other risk factors unknown to us that could contribute to problems in these patients. Indeed, some may even argue whether or not chondrolysis was present in some of the patients in this case series, such as Case 3. Early arthritis can be seen especially in females after anterior cruciate ligament injury and reconstructive surgery as well as after meniscectomy. As a result, there is much discussion on the etiology of chondrolysis as other entities have been hypothesized, and some surgeons do not completely accept intra-articular pain pumps as a specific causative factor2.
Research has been performed to elucidate factors contributing to chondrocyte death, including the concentration of bupivacaine, the time of exposure to the articular cartilage, and effects of epinephrine3-6. Presumably, if one of these factors proved to be the key trigger in chondrocyte death, then eliminating that factor while retaining other pain-blocking properties could be considered. However, the facts are that this entity is more prevalent in recent orthopaedic experience, that it most commonly affects young patients with relatively normal joints prior to the index operation, and that it has devastating, life-altering consequences. As in the study by Noyes et al., often the only alternative to treat the chondrolysis is joint replacement. This is similar to the experience of Levy et al., who performed total shoulder arthroplasty on eleven patients with shoulder chondrolysis7. The level of evidence of the study by Noyes et al. is low, and similar studies of chondrolysis in the shoulder also have low levels of evidence. There are no absolute proven causes and effects that can be derived from the Noyes study. But the weight of the evidence in these Level-IV studies and the severity of the outcomes mandate that we not use indwelling intra-articular local anesthetic-delivering devices to help with postoperative pain control in any joint. The potential risks are simply too great and the benefit for the patient is too small. This is a circumstance in which Level-IV evidence should speak loudly to all of us and should alter how we practice.