Keywords
cartilage repair - patella - costal graft - rib perichondrium
Introduction
Full-thickness articular cartilage defects do not heal spontaneously.[1] Patients with isolated cartilage defects may not have clinically and functionally significant problems. However, most of them have early degenerative changes, pain, and disability.[2] In the last years, different tissues and techniques have been developed to restore articular defects of the knee.
Microfractures,[3] autologous chondrocyte implantation (ACI),[4] matrix-induced autologous chondrocyte implantation,[5]
[6] autologous matrix-induced chondrogenesis (AMIC),[7] AMIC improved with autologous bone marrow concentrate,[8] mosaicplasty,[9] osteochondral allograft transplantation[10] and other techniques present limitations and no consensus regarding which method is superior has been obtained.[11] In addition, irrespective of the surgical technique used, hyaline cartilage has been obtained only in selected cases, without restoring articular cartilage microarchitecture.[5]
[12]
[13]
After the medial femoral condyle, the patella is the second most common location in the knee for the occurrence of chondral lesions.[14] Furthermore, despite the wide selection of technique available, it has been well established that in the patellofemoral compartment outcomes are generally worse than in the tibiofemoral joint.[15] For these reasons, the best technique remains to be addressed; the main goal in managing patellar injuries should be to restore the cartilage surface with grafts of hyaline cartilage to re-establish the biomechanical properties of the tissue restoring knee function. The use of autologous costal cartilage graft for the treatment of articular defects of the knee in humans has never been described before. Only limited and promising results have been obtained by animal models with costal fragments.[16] Indeed, Du et al sliced rib cartilage into 3- to 5-mm fragments and then harvested cartilage grafts in the rabbit knee lesions in one step technique.
Considering this imperative, we developed a new technique for repair articular cartilage defect using autologous costal cartilage graft with its perichondrium.
The main elements contributing to the rationale for this choice were: (1) the graft is autologous and of hyaline nature; (2) the perichondrium of the graft has chondrogenic potential[17]; (3) the costal graft is widely used in reconstructive surgery[18]
[19] and usually it has a low donor site morbidity[20]; (4) the graft may be properly sized to cover large and full-thickness articular defects; (5) the method is “one-step” and has a low cost.
Case Description
In September 2017, a 15-year-old male was referred to the Department of Orthopaedics of the Polytechnic University of Marche (Italy) for anterior knee pain. Symptoms were exacerbated by going downstairs, running, jumping, and squatting. In addition, the patient described the movie sign, in which anterior pain was increased after prolonged sitting. No signs of patella instability were revealed. The Lachman test, anterior drawer test provided negative results. No signs of meniscal injuries were found. Magnetic resonance imaging demonstrated a focal cartilage defect in patella that seemed to be grade III according to the International Cartilage Repair Society (ICRS).[21] Static and dynamic CT examination did not show relevant features of patellofemoral malalignment.
Patient had no history of malignancy, systemic inflammatory diseases, and neurologic or cardiovascular disorders. In addition, he agreed with a strict postoperative rehabilitation protocol.
Prior to surgery, patients failed the nonsurgical management of injections, bracing, and physical therapy that focused on quadriceps strengthening, peripatellar mobilization, core strengthening, abductor strengthening, and physiotaping.
After discussing with the patient and his parents about the possibilities of this new technique in comparison to other techniques, and after the signature of the informed consent, we elected to repair the diseased joint with an autologous costal cartilage graft.
Surgical Treatment
Under general anesthesia, with a tourniquet located in the thigh, a knee arthroscopy was performed. Under arthroscopy vision, we confirmed the diagnosis of patellar cartilage defect and excluded other possible lesions. We observed no meniscal injuries, cruciate ligaments ruptures, or osteoarthritis of both patellofemoral and tibiofemoral joint. The defect was classified grade III according to ICRS classification.
The unique anatomy of the patellofemoral joint makes surgical exposure to the patellar articular surface difficult to achieve arthroscopically; thus after the arthroscopic diagnosis, we preferred an arthrotomy through a lateral parapatellar incision that allowed a direct and perpendicular approach to the patellar lesion.[6]
[22] With the patella everted, clear visualization of the defect was possible ([Fig. 1]).
Fig. 1 (A) Cartilage defect of the medial facet of the patella. (B) The lesion after debridement.
The surgical procedure commenced with the assessment and debridement of the full-thickness articular cartilage lesion. To debride the lesion, a curette and a motorized shaver were used to remove any unstable cartilage overlying or surrounding the chondral defect. The calcified cartilage layer at the base of the defect was removed using a curette to expose the subchondral bone.
An awl was used to make multiple small perforations in the exposed subchondral bone. The holes were performed 6 mm deep and placed 3 to 4 mm apart to ensure that the holes did not become confluent during the procedure. We began at the periphery and then progressed toward the center of the defect. The lesion measured 1 × 1.5 cm ([Fig. 2]).
Fig. 2 Size of the chondral defect after microfractures.
Once measured the patellar defect by the ruler, we moved to the thorax to harvest the costal cartilage graft. A skin incision of approximately 3 cm was made along the major axis of the seventh rib in proximity of the right costosternal joint ([Fig. 3]).
Fig. 3 Cutaneous scar at 3 months after surgery. The skin incision about of 3 cm was made along the major axis of the seventh rib in proximity of the right costosternal joint.
Separation of the overlying muscles was performed to expose the rib, a subperichondrial dissection of the seventh costal cartilage with delivery of the distal part of the rib was done and the required length was harvested. A 15-blade scalpel was then used to make incisions both at the medial and at the lateral aspect of the sized graft. An elevator was then used to remove the graft. The incisions should extend through the cartilage but not violate the underlying perichondrium. Indeed, special attention should be laid to preserve as intact the three sides of the rib ([Fig. 4]).
Fig. 4 (A) The surgeon measured the size of the graft. (B) Schematic representation of costal graft (G, Graft; P, perichondrium).
The graft was carefully shaped and impacted into the defect. Its height matched with that of the neighboring cartilage, because an uneven articular surface could alter the biomechanical functionality of the patellofemoral joint.[15] The graft was positioned with the perichondrium facing toward the trochlear groove ([Fig. 5]).
Fig. 5 (A) The implantation of the graft during surgery. (B) A schematic representation of implantation of the graft throughout nonabsorbable sutures across the patella (C, cartilage; D, defect; G, graft).
To fix the graft in compression, we applied two nonabsorbable sutures through the graft; then we performed four holes across the patella. Subsequently, we put the free ends of the sutures through the patella and we tied two knots in the surface opposite to the patellofemoral joint. To ensure the graft in the lesion, we passed two absorbable sutures between perichondrium and the neighboring cartilage. After the implantation of the graft, the tourniquet was removed.
Lastly, we filled the borders of the implant with fibrin glue to make the surface smooth and to strengthen the graft. A drainage has been introduced to avoid local hematoma and then it was removed in the second postoperative day. The incisions were closed with absorbable sutures on the fascia and subcutaneous planes and with nonabsorbable sutures for the skin.
Postoperative Care
When he was discharged from the operating theater, the affected leg was immobilized in a brace in full extension for 48 hours; then continuous passive motion was used for the first month after surgery. Weight bearing was not allowed for 4 weeks, the patient was allowed to walk with crutches without putting weight on the affected leg. Progressive weight bearing on the affected limb and active movement during physiotherapy were allowed from the second month following surgery.
Discussion
We developed this technique on the basis of previous histological, immunohistochemical, and ultrastructure characterization of costal cartilage.
First, from a biological point of view, the costal cartilage represents the main source of hyaline cartilage in mammals and it is characterized by histological similarities to the articular cartilage.[23] Furthermore, it is surrounded by rib perichondrium, whose chondrogenic capacity was demonstrated by Skoog et al in 1972.[24] Summarizing, the graft presents the histochemical (hyaline) and microarchitectural features close to the articular cartilage; thus, it could support the biomechanical loading imposed by the joint with the peripheral perichondrium that might promote the integration mechanism. Moreover, the use of an autologous tissue avoids any adverse reactions.
Second, from a surgical point of view, it is easy to fit the costal graft in the lesion; in case of extensive or multiple defects, multiple costal cartilage grafts might be harvested from the same incision; it is a nondemanding and low invasive technique with minimal donor site morbidity. Lastly, the method proposed may be efficient in cost-benefit terms, because it is a “one step” and low cost procedure.
On the other hand, the method presents some critical issues. We do not know if the borders of the costal graft may be integrated in the neighboring cartilage and if the graft may be efficiently anchored to the bone through endochondral ossification. Moreover, the long-term clinical efficacy of the method remains to be evaluated.
