Carpentry still works. When and how to incorporate osteotomy for the treatment of meniscus and chondral pathology. Articular cartilage lesions of the knee are common and present a complex pathologic entity. Articular cartilage has limited intrinsic ability to heal because of its avascular nature, as well as its dense extracellular matrix that limits the mobility of cells and the rare progenitor cell. Traumatic knee injuries have a seven times increased risk of development of osteoarthritis, therefore prevention strategies are essential. When approaching a patient with a symptomatic chondral defect, several factors should be taken into account, including the patient's age, gender, activity level, BMI, as well as expectations. Other factors include more of the mechanical environment, as well as the lesion characteristics itself, which include the location of the lesion, size, the depth, bony involvement. And then when you look at the mechanical environment, you have to think about the alignment, ligament stability, and meniscus status. In general, smaller lesions can be managed by marrow stimulating procedures, debridement, or even osteochondral autograft transfer, whereas larger lesions can be filled in with cell-based therapies or allografts. So why is the mechanical environment important and why does alignment matter? In the native knee, 60% of the weight-bearing force is transmitted through the medial compartment. Dynamic physiologic loading contributes to articular cartilage health and homeostasis, but overloading can occur with malalignment and that is detrimental to cartilage health. Various deviation of even something as small as three degrees is enough to increase peak stresses in the medial compartment. When you add meniscus damage to the malalignment, that also leads to a prediction of medial compartment cartilage damage. Valgus, although less common, can lead to the same effect laterally. Biomechanically, there have been studies that have proved the potential of unloading osteotomies in terms of actual load reduction to that joint. Unloading osteotomies are a powerful tool to alter mechanical loading and improve loads, and these are essential to long-time survivorship of joint preservation techniques, such as cell-based therapies or meniscus allograft transplantation. Crutcher et al. had showed that there was a 56% failure of cartilage restoration procedures if there was untreated malalignment. So in a retrospective insurance database study looking at cartilage procedures such as ACI, autologous chondrocyte implantation, or osteochondral allograft, with or without osteotomy, reoperation rates were markedly higher in those joint preservation procedures that did not do unloading osteotomies. Graft survivorship has also been shown to be affected by unloading osteotomies. In this cohort of 60 patients, persistent malalignment increased the risk of graft failure over time. Similarly to coronal malalignment, catavatic biomechanical studies have shown the unloading effect of a tibial tubercle osteotomy on the contact pressures within the patellofemoral joint. So in a systematic review looking at 11 studies with 366 subjects, there's no difference in postoperative complications was noted between patients undergoing cell-based cartilage regenerative procedures in the patellofemoral joint with or without osteotomy. However, patient-reported outcomes were significantly greater in those with the osteotomy. In a separate cohort of patients in the military population, retrospectively reviewed included 72 patients with a minimum of two-year follow-up, where the majority of these patients had unloading osteotomies and were able to return to high-demand heavy work. With regards to specific varus malalignment, a systematic review was performed identifying 839 knees and noted that there was a favorable relationship between high-tibial osteotomy and cartilage restoration procedures that with improved fly-sham knee scores and a relatively low conversion rate to arthroplasty. In this German cartilage registry study, Neumeier's group set out to investigate the clinical advocacy of unloading osteotomy in patients with focal chondral defects of the medial femoral condyle. Because this was a non-randomized nature of the study, a one-to-one propensity score matching was performed to reduce the bias and enhance comparability of these two groups. Cartilage repair alone was compared against cartilage repair with an unloading osteotomy, and patients with a concomitant osteotomy to correct varus had better functional scores and less pain at three years. Overall, I would say that there is a clear bias towards addressing concomitant malalignment in joint preservation procedures. Traditionally, any varus deformity of greater than five degrees was indicated for correctional osteotomy in patients with cartilage defects. This study here looks at cell-based therapy and high-tibial osteotomies in malalignment of less than five degrees. Overall, patients had less re-interventions with osteotomy when compared to cell-based therapy alone. Although there was a trend towards less symptoms and better outcomes, this was not considered to be statistically significant. So now we've looked at malalignment in chondral pathology alone. What happens when we look at this in addition to meniscus in the mechanical environment? This systematic review looked at 69 studies of over 4,500 patients with identifying about nine studies with high-tibial osteotomy and cartilage, whereas there were three studies of high-tibial osteotomy and meniscus allograft transplantation. Overall, as is typical with a lot of these studies, there was poor quality of evidence that was noted with the modified Coleman methodology scores, because these are often small cohorts and often they're retrospective in nature. At five-year follow-up, patients with high-tibial osteotomy and cartilage restoration had 98.7% survivorship compared to HTO alone at 92.4%. Those patients who had HTO and meniscus allograft transplantation had a slightly lower survivorship at 90.9%. Other considerations when you look at osteotomy include what type of osteotomy, either looking at lateral closing wedge or medial opening wedge. Closing wedge requires a more precise bony cut and potentially has a risk for damage or injury to the common peroneal nerve and the proximal tib-fib joint. Opening wedge osteotomy allows for a little bit more intraoperative adjustment, but may have issues with delayed versus nonunion, as well as issues with having a graft. Osteotomy execution is dealer's choice and should be done at the same time as cartilage preservation procedures. As with any surgery, managing expectation is key. Patients with, in a study looking in AJSM, patients with HTO and osteochondral allograft could return to sports at about 80% of the time, but usually not at pre-injury level. So in deciding where to do the osteotomy, which is beyond the scope of this talk, distal formal osteotomy can be done to manage the valgus knee, as typically seen when you have a hypoplastic lateral formal condyle and with lateral meniscus pathology and gradual wear of the lateral compartment. As with HTO, opening wedge versus closing wedge osteotomies have comparable survivorship, but there often is a little bit higher incidence of hardware removal or complication with an opening wedge osteotomy, often with the IT band. So studies assessing the distal femoral osteotomy with concomitant joint preservation procedures are limited. In this small cohort of patients with a large lateral chondral lesion undergoing a variety of procedures to include cell-based therapies, grafting, or even microfracture, the trends showed higher KUS subscores in patients with isolated cartilage treatment compared to meniscus transplant. There's no difference in outcomes that were noted with or without realignment osteotomies, but again, this is a very heterogeneous group, so it's very hard to make comparisons between all of them. In this small cohort of 31 patients undergoing osteotomy for either concomitant cartilage preservation procedure or arthritis, survivorship was much higher at fires for the cartilage preservation group, and this can be likely for a variety of reasons. These are pathologies that are not technically similar, and age is likely a confounding variable. When assessing return to sport, this retrospective review of 13 patients who underwent distal femoral osteotomy with either cartilage or meniscus procedures resulted in return to sport at roughly 11 months after surgery. There's no difference between Mark's activity level or IKDC between closing or opening wedge osteotomies. Lastly, in this systematic review, severe cartilage damage was associated with poor survivorship for meniscus allograft transplantation. What was interesting was that this group found that meniscus allograft transplantation with concomitant osteotomy in malaligned knees had similar survivorship compared to simple meniscus allograft transplantation in neutral alignment knees, but there was no subgroup analysis in terms of varus or valgus in this study. So in conclusion, what did we learn? Although biomechanically we have shown that osteotomies can reduce load, translation with clinical evidence is limited. Realignment osteotomy is an integral part of the surgeon's toolbox when it comes to treatment of complex knee pathology and joint preservation. Overall, survivorship is improved with unloading osteotomy, but there's a paucity of high-quality evidence for the long-term outcomes that prove that unloading osteotomy with cartilage procedures is superior to osteotomy alone. These are the references.

osteotomy

meniscus

chondral pathology

osteoarthritis prevention

malalignment