Management of Complex Osteochondral Defects: Osteochondral Allografts and Juvenile Particulated Cartilage
Kevin D. Plancher, MD
Allison M. Green, PhD
Stephanie C. Petterson, MPT, PhD
A 29-year-old female horseback rider and Pilates instructor with a history of three previous right knee surgeries presents to the clinic with right medial knee pain. The index procedure was a hamstring autograft anterior cruciate ligament (ACL) reconstruction by another orthopaedic surgeon in 2001. After falling from a horse in 2010, she subsequently underwent arthroscopic microfracture, removal of loose bodies, and partial, medial, and lateral meniscectomies at an outside institution, which did not resolve her right medial knee pain. She then underwent a revision arthroscopic microfracture procedure and medial meniscal repair in 2011. While the patient returned to horseback riding and Pilates, she reported her right knee never felt the same. She presented to our clinic in 2012, approximately 1 year after the revision microfracture surgery, with persistent right medial knee pain that worsens going up and down stairs, with prolonged standing and riding, and when she sits with her legs crossed.
Physical examination revealed no effusion or edema and tenderness over the medial joint line and posteromedial femoral condyle of the right knee, but not over the medial meniscus and there was no tenderness over the lateral joint line. Her right knee range of motion (ROM) was 0 to 135 degrees with pain on hyperflexion and hyperextension. Lachman, pivot shift, and anterior drawer tests were negative, but she exhibited a positive McMurray test. Varus and valgus stress testing revealed a 2 cm opening and she had a neutral limb alignment. She demonstrated 5 out of 5 symmetric quadriceps strength and denied any numbness or tingling. Physical examination of her left knee was insignificant.
MRI revealed loss of volume in the body and posterior horn of the medial meniscus, consistent with degeneration and a prior partial medial meniscectomy. There was a vertical signal in the posterior horn of the medial meniscus, possibly indicating a new, small vertical tear. There was grade IV chondral loss on the posterior weight bearing third of the lateral femoral condyle and on the anterior aspect of the medial femoral condyle (Figures 1a, 1b). Chondral delamination involving the medial facet of the patella with intact articular cartilage was also noted.
Based on her clinical exam and MRI results, a diagnosis of medial meniscus tear and osteochondritis dissecans was made. A non-operative course was initially attempted including a five week course of topical anti-inflammatory cream and Meloxicam, as well as a corticosteriod injection, which only provided temporary relief. The patient reported that the corticosteriod injection worked for 3 days before her pain returned, the anti-inflammatory cream provided relief for only about an hour, and Meloxicam only alleviated her pain for about 2 hours. The patient expressed interest in operative intervention and the use of osteochondral allografts to augment healing of her osteochondritis dissecans was discussed.
Prior to the procedure, the patient received general endotracheal anesthesia and intravenous antibiotics. Inferolateral, inferomedial, and accessory medial portals were placed, a synovectomy was completed from the medial to lateral side, and loose fragments were removed.
The ACL was probed and demonstrated a chronic, grade 1 tear of approximately 10% of the width of the ligament distally. Visible sutures from the hamstring graft were removed and the ligament was debrided. The PCL, MCL, and LCL were normal. The popliteus was synovitic and was debrided.
Next, attention was turned to the degenerative medial meniscus tear. Careful inspection revealed a complete, complex radial tear. All radial flaps and horizontal cleavage (white-red) that had reloosened since the previous repair were removed, as well as the multiple sutures from the previous repair. The tear was repaired by trephination. In the red-red posterior third, multiple sutures from the previous repair were again visualized, as well as flap tears resembling a bucket handle tear. The sutures, as well as the posterior horn of the meniscus, were removed to prevent any rubbing on the chondral surface. The lateral meniscus had an incomplete, degenerative, flap tear in the middle third of the meniscus (white-white) which was partially excised.
The chondral surfaces were then assessed. The medial femoral condyle demonstrated grade 4 osteochondral changes with a large 9x9cm defect. The medial tibial plateau, lateral femoral condyle, and lateral tibial plateau all displayed minimal grade 1 changes. The trochlear groove displayed grade 3 changes with a 1.9x2.1cm defect, and the patella demonstrated grade 2 osteochondral changes in the medial and lateral facets. The medial femoral condyle and trochlear groove also displayed evidence of previous microfracture. A chondroplasty was performed through the grade 2 changes on the patella and through the trochelar groove.
Next, the medial femoral condyle was more closely inspected, revealing soft, depressed, crab meat, fissuring, and fragmented chondral defects covering 85% of the condyle surface as well as the previously noted defect (Figures 2a-b). The defect was covered with a sizer to determine the best osteochondral allograft configuration to use. A size 9 graft was selected to be centered over the area of the defect. The exact length of the graft was measured to prevent any errors due to any slight variablilities, then the recepient site was prepared. The portal was opened with an 11 blade and spread with a Kelly, then the punch of the obturator was introduced. The obturator was moved from the punch to twist the operator 45 degrees counter-clockwise. Next, the mallet was introduced and used to advance the punch, which was positioned absolutely perpendicular to the articular cartilage of the medial femoral condyle in all directions. The depth was checked periodically around the entire circumference to measure perpendicularity and alignment. Bone was removed with the punch.
After the correct depth was achieved, the impaction cap was removed and the drill bit was connected and inserted to the 9mm end of the punch, which would function as the drill guide to maintain alignment (Figure 3). Following drilling, the hole was well-irrigated, and a 0.564 K-wire was used to drill a small hole in the center of the larger hole to allow blood flow to the back of the graft. The osteochondral allograft was then loaded into the delivery device, recessed approximately 1mm at the end. The delivery device was positioned over the recepient site to the exact same alignment then released into the hole (Figure 4). The overhanging 1mm was gently tapped in place until flushed with the cartilage (Figure 5). This exact procedure was repeated a second time using a 7mm osteochondral allograft plug. Following placement of the second osteochondral allograft plug, the articular surface was copiously irrigated. Next, the trochlear groove was visualized and the previously mentioned 1.9x2.1cm defect was covered with a particulated juvenile cartilage graft and fixed using fibrin glue.
Following placement of the osteochondral allograft plug and particulated juvenile cartilage, the parapatellar incision, subcutaneous tissue, and portals were closed with Vicryl or Monocryl, then Steri-Strips, dry sterile dressing, and Xeroform were applied.
Next, the right hip was meticulously prepped and draped for stem cell harvest through a small nick in the skin 5cm posterior to the anterior superior iliac spine was created. The inner and outer tables were identified. The fluted trocar provided with the bone marrow aspirate concentration (BMAC) system was placed in the midsection between the tables with a mallet. The trocar was turned about 15 degrees, and a syringe preloaded with anticoagulant was injected. Two 30mL syringes of bone marrow were aspirated with a 15 degree rotation of the handle of the Tuohy needle between aspirations. The wound was irrigated copiously and closed with Vicryl, 3-0 Vicryl subcutaneous, and subcuticular Monocryl before steri-strips and a dry sterile dressing were placed. The collected aspirate was concentrated according to manufacturer’s directions, and the resultant 10mL of stem cells were injected into the patient’s knee joint, visible through an 18-gauge spinal needle from a suprapatellar lateral approach.
The patient was then fitted for a brace of 30 to 75 degrees to allow for engagement of both the osteochondral allograft plug at 75 degrees and the particulated juvenile cartilage graft at 30 degrees. The patient was then returned to the recovery room in stable condition.
The day after surgery, the patient reported taking a 500mg Vicodin tablet in the morning and experienced a little pain following the surgery. She took anti-inflammatories for the first 2 weeks as needed. By 16 days after surgery, the patient reported icing as her only form of pain management and was pain-free at 6 weeks post-operatively.
Post-operative rehabilitation included progressive ROM using a CPM machine and weight bearing as tolerated for the first 6 weeks. Exercises during the first 6 weeks included biking with no resistance, straight leg raises, and open chain strengthening exercises. The patient progressed to full weight bearing, full ROM, and closed chain strengthening exercises from weeks 6-12 post-operatively. During weeks 12-26, the patient continued with progressive strengthening exercises and initiated a jogging program.
Post-operative MRIs revealed progressive osseous incorporation of the osteochondral allograft in the medial femoral condyle with reparative fibrocartilage overlying the graft at both 5 months (Figures 6a-b) and 12 months post-operatively (Figures 6c-d). One year after surgery, the patient reported that her knee was doing well. She was able to do the activities that she wanted to do including Pilates, barre classes, and horseback riding. She reported mild pain at the medial aspect of her knee only after very long walks and her barre classes. She was taking Motrin 400mg as needed for pain and was very happy with her knee progression. The patient is now 3 years status post-osteochondral allograft implantation with no pain and full return to all desired activities without any restrictions (Figures 7a, 7b).