Complex Problems in Knee Articular Cartilage

Chapter 68


Complex Problems in Knee Articular Cartilage








Patients with knee pain often have coexisting pathoanatomic conditions at the index clinic visit, which may in turn have multiple causes (Box 68-1). With advancements in surgical techniques, available grafts, and imaging modalities, the ability to successfully perform complex cartilage procedures in even the most challenging patient is improving. However, this aforementioned group of patients with multiple coexisting knee pathologies remains a difficult population, especially with regard to determining which (if any) of the lesions is the cause of symptoms. Cartilage lesions may be simply incidental in nature, and the decision to treat is based on their confirmed contribution to a patient’s symptomatology.



Box 68-1   Common Coexisting Knee Pathologies




The combination of malalignment, ligamentous instability, and chondral and meniscal damage presents multiple challenges.1 Corrective procedures for each of these problems performed in isolation have historically produced adequate results; however, combined procedures to treat combined pathologies have proven essential for the success of any single procedure.1,2 Consideration of both patient-specific factors (e.g., age, activity level, expectations) and disease-specific factors is a requisite for treatment planning and optimization of short- and long-term clinical outcomes.


Many surgical options are available for the patient with multiple knee pathologies and are often used in combination. Meniscal deficiency can be treated with debridement, direct repair, or meniscal allograft transplantation. Ligamentous pathology can be addressed with direct repair or reconstruction depending on the region of injury. Articular cartilage pathology can be addressed with a variety of procedures including debridement, microfracture, autologous chondrocyte implantation (ACI), and osteochondral autograft or allograft. Finally, medial compartment disease with varus malalignment can be addressed with a high tibial osteotomy (HTO) that unloads the diseased medial compartment, and lateral compartment disease with valgus malalignment can be treated with a distal femoral osteotomy (DFO) that unloads the lateral compartment. More recently, HTO has been used as a concomitant malalignment corrective procedure in patients undergoing cartilage and/or meniscus surgery in an attempt to offload the compartment in which cartilage surgery is performed.1–4 A recent systematic review performed by Harris and colleagues2 analyzed clinical outcomes in patients undergoing combined meniscal allograft transplantation and cartilage repair or restoration. Of the six studies included, 110 patients were identified as having undergone meniscal allograft transplantation and either ACI (n = 73), osteochondral allograft transplantation (n = 20), or osteochondral autograft transplantation (n = 17). In addition, three patients underwent concomitant microfracture. Of note, 33% of patients (36 of 110) underwent other concomitant procedures including HTO or DFO, ligament reconstruction, and/or hardware removal. The authors noted improved outcomes in combined procedures compared with isolated surgery in four of the six studies. Overall, 12% of patients experienced failure of their combined procedure that necessitated revision surgery, and 85% of these failures were noted to be related to the meniscus procedure as opposed to the cartilage procedure.2


For all of these procedures, whether performed in isolation or concurrently, proper patient selection and determination of which lesion(s) is responsible for generating symptoms are crucial. As mentioned previously, treating incidental lesions must be avoided.



Pathophysiology


In a knee with multiple pathologies (meniscal deficiency, chondral defect, malalignment, and ligament instability), each entity must be considered individually with respect to its influence on the overall status of the knee. Meniscectomy is a commonly performed procedure in sports medicine. It is minimally invasive and can produce satisfactory outcomes in a majority of patients, especially those desiring a quick return to activity. However, the procedure is not without risks when it comes to the long-term health of the knee. Subtotal meniscectomy decreases joint contact area5 and increases peak stress.5 After subtotal or total meniscectomy, there is a fourteenfold increased relative risk of developing unicompartmental arthritis.6–8 Furthermore, multiple studies have demonstrated worse outcomes associated with young age, chondral damage found at time of menisectomy,9,10 ligamentous instability,11–13 and/or tibiofemoral malalignment. In addition, meniscal repair as well as meniscal transplantation have less favorable outcomes when performed with untreated concomitant instability, malalignment, and/or articular cartilage disease.1,4,14–16 Thus, although addressing multiple coexisting pathologies in a single patient’s knee is certainly challenging, neglecting to correct concomitant comorbidity can compromise overall results and in the worst case scenario lead to a uncorrectable salvage situation.


Damage to the articular cartilage occurs for a variety of reasons, including mechanical overload, developmental defects, genetic failures, and traumatic impact. Articular cartilage injury leads to an increase in degenerative joint disease, especially with bipolar “kissing” lesions. Full-thickness chondral injuries can be extremely problematic, causing knee swelling, pain at night and with rest, and severe activity-related pain.17,18 Furthermore, it is necessary to determine if a chondral lesion has any underlying subchondral bone changes because this feature would affect decision making in the perioperative period.


Knee malalignment causes excessive loading of articular cartilage, which can lead to degenerative joint disease. The mechanical axis (center of femoral head to intercondylar eminence to center of ankle) of the leg is different from the weight-bearing axis (center of femoral head to center of ankle). Because the anatomic axis of the femur differs from the mechanical axis, the normal anatomic weight-bearing axis of the knee is approximately 5 to 7 degrees of valgus. Furthermore, in a normal knee approximately 60% of the weight-bearing force is transmitted through the medial compartment. Varus malalignment19 shifts the center of the knee joint lateral to the mechanical axis, leading to medial tibial cartilage volume and thickness loss, as well as increases in tibial and femoral denuded bone.19 Valgus malalignment shifts the center of the knee medial to the mechanical axis, leading to increased, unbalanced lateral-sided forces. Osteotomy procedures (HTO, DFO) alter the biomechanical axis by shifting load away from the damaged compartment. The pathophysiologic principle of this procedure is to correct the weight-bearing axis if possible to avoid rapid and irreversible progression of unicompartmental degenerative joint disease.20–22



Preoperative Considerations



Patient Presentation


Patients with complex, combined knee pathologies typically report unilateral, single compartment knee pain. Often their symptoms are chronic in nature, because it takes time for any one of these isolated injuries to have an additive effect on another. This goes to the core of the complexity of treating patients with multiple knee pathologies. Diagnosing and treating any injury occurring in isolation is usually rather straightforward; however, multiple concurrent injuries tend to expedite the development of degenerative disease. Therefore these patients may also be seen after at least one, if not more, previous (and unsuccessful) surgical intervention. Only occasionally are these types of patients seen acutely after a traumatic event. Other common components of the patient presentation are outlined in Table 68-1.



The history of the patient with combined knee pathologies will not be as straightforward as that of the typical sports medicine patient with a defined traumatic twisting, pivoting, or instability event. Therefore it is vital for the clinician to be suspicious for a knee with combined pathology. Nonetheless, it is important to elicit a certain requisite set of symptoms—specifically, localized pain (retropatellar, medial or lateral), swelling, mechanical symptoms, and/or instability (side-to-side instability, or instability with pivoting and twisting).



Physical Examination


For any patient with combined knee pathology, a standard physical examination of both knees and lower extremities should be performed. Specific physical examination maneuvers can include the following:



• Inspection



• Palpation



• Active and passive range of motion



• Strength assessment



• Hamstring flexibility and iliotibial band assessment (Ober test)


• Neurovascular examination


• Patellar examination



• Tests of stability and special tests



Patients with unilateral joint effusion are likely to have cartilage pathology, although this physical examination finding is not specific. Patients with tenderness to palpation posterior to the midline of joint line are more likely to have meniscal pathology, whereas those with tenderness anterior to the midline of joint line may have patellofemoral, chondral, or meniscal (displaced tears) pathology. Nevertheless, with combined pathology, symptoms can be difficult to differentiate. Most patients have preserved strength and range-of-motion, unless their degenerative disease has progressed far enough to cause weakness and/or stiffness.


Leg length and gait should be assessed in every patient as well, because these findings may have significant implications on surgical planning. Overall alignment and the presence of clinical genu valgum or varum should also be documented.



Imaging


Imaging for patients with combined knee pathologies can include the following:



• Radiographs



• Magnetic resonance imaging (MRI)


• Computed tomography (CT)


MRI is useful for examining soft tissue integrity. Specific sequences can be used to identify articular cartilage, menisci, ligamentous structures, and other intra-articular structures and pathology. In general, a minimum of a 1.5-Tesla MRI is required for adequate resolution to view cartilage abnormalities. Bone marrow edema seen on MRI can be indicative of unicompartmental overload. CT scans can be helpful as adjunctive imaging modalities, especially in the patient with prior surgery (e.g., bone tunnels in previous anterior cruciate ligament [ACL] reconstruction). Other imaging modalities, including bone scans, may provide information regarding degenerative activity in the condyles, plateaus, or patella.




Treatment Options




Operative Treatment


See Figs. 68-2 to 68-5 for details of the operative treatment.



Related posts:

Open Repair of Posterior Shoulder Instability Autologous Chondrocyte Implantation in the Knee Allografts for Anterior Cruciate Ligament Reconstruction All-Inside Anterior Cruciate Ligament GraftLink Technique: Second-Generation, No-Incision Anterior Cruciate Ligament Reconstruction Primary Repair of Osteochondritis Dissecans in the Knee Arthroscopic Meniscus Repair: All-Inside Technique

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Sep 11, 2016 | Posted by in SPORT MEDICINE | Comments Off on Complex Problems in Knee Articular Cartilage

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