Abstract
Patellar chondral lesions are disabling injuries that are mechanically limiting and lead to the further progression of osteoarthritis. Patellar chondral lesions are identified in 11.0% to 34.6% of routine knee arthroscopies. Multiple surgical interventions, including chondroplasty, microfracture, osteochondral transplantation, and matrix-induced autologous chondrocyte implantation, have been described, but the best treatment method is debated. For isolated chondral lesions of the patella, osteochondral autograft transplantation from a lesser weightbearing surface in the knee has reported mid- and long-term success. This Technical Note describes isolated osteochondral autograft transplantation for a focal chondral defect of the patella.
Technique Video
Lesions of the patellar cartilage present unique challenges for physicians due to the repetitive stress of everyday activities on the patellofemoral joint. They can be mechanically limiting and lead to the early progression of osteoarthritis. The incidence of patellar chondral defects found during routine arthroscopy ranges from 11.0% to 34.6%,1,2 and many progress unnoticed for extended periods due to the force-resistant surface and native thickness of the patellar cartilage surface.3 Conservative management is typically indicated to restore native mechanics to the patellofemoral joint. Still, when measures fail to provide symptomatic relief, surgeons face the challenge of developing reproducible resurfacing techniques with predictable outcomes.4,5 Current evidence on surgical management of isolated patellofemoral chondral defects is limited, but existing methods are primarily inclusive of 3 repair mechanisms: marrow stimulation, osteochondral transplantation/grafting, and matrix-induced autologous chondrocyte implantation procedures. Osteochondral autograft transplantation (OAT) exists as the only option that replaces autologous hyaline cartilage, but limitations exist based on surrounding cartilage conditions and donor site morbidity. Improved outcomes have been reported for short- and mid-term follow-ups for OAT to treat osteochondral defects of the patella.2,4,6 In this technique, we describe a single-stage OAT for an isolated chondral defect of the patella.
Surgical Technique
A detailed video of the assessment, approach, patellar OAT, and chondroplasty is shown in Video 1. The step-by-step guide and surgical pearls are included in Table 1.
Table 1.
Step-by-Step Guide and Surgical Pearls for Isolated Osteochondral Autograft Transplantation for a Focal Chondral Defect of the Patella
| Step-by-Step Guide | Pearls |
|---|---|
| Anteromedial and anterolateral parapatellar portals are made, the arthroscope is inserted into the joint, and the joint is insufflated with normal saline. | The suprapatellar pouch, lateral and medial gutters, and intra-articular surfaces of both compartments are assessed. The medial and lateral menisci are palpated with a probe to evaluate attachment areas. Next, the ACL and the PCL attachments are confirmed, ensuring the ligaments are taut. |
| The chondral defect is identified on the patella, and the size of the defect is approximated. | Palpation with a probe occurs to establish the margins of the patellar defect based on the integrity of the cartilage, observing if any delamination has occurred. |
| An anterior midline incision is made 6 cm proximal to the superior pole of the patella to just distal of the tibial tubercle, exposing the extensor mechanism. This is followed by a medial parapatellar arthrotomy. | The interval for medial arthrotomy separates the vastus medialis oblique and the quadriceps tendon. A Z retractor and a penetrating towel clip are used to secure the patella in an everted lateral position. |
| The chondral defect on the patella is measured and prepped for removal. | The diameter of the defect is measured to determine the size of the autograft transplant needed. Once the margins are identified, a surgical marking pen is used to outline the fibrillated cartilage borders. |
| A chondroplasty is performed, and the defective tissue is removed with a series of reamers, rongeurs, and pick-ups. | If chondral flaps were not removed with the shaver during arthroscopy, they should be removed first. Reaming of the defect begins by establishing the center and placing a guide pin at this point. This is overreamed to a desired depth of the bone. A series of rongeurs, blades, and pick-ups to remove excess portions of the pathologic cartilage. |
| Attention is now brought to the harvest site for the autograft on the superolateral portion of the lateral femoral condyle, and the measured diameter of the defect is used to match the diameter of the autograft plug. The harvester is removed and ready for final transplantation into the patella. |
The harvester is inserted perpendicular to the joint to avoid offset prominence within the graft. An osteochondral plug is harvested from a lesser articulating portion of the superolateral trochlea by malleting down the harvester to the matching desired depth. |
| The osteochondral donor plug is inserted into the recipient site. It is then firmly and carefully impacted into place. | The pin at the center of the patella is removed from the defect site, and suction is used a final time to remove any small loose bodies. The plug is placed in the prepared recipient site, and the inserter is slowly turned clockwise to deploy the plug into the patella. A towel and impactor are then used to reduce any prominent portions of the plug into the recipient site to align contiguously with the patellar cartilage margins. |
| Deep and superficial tissues are closed in a layered fashion. | The medial arthrotomy is closed first, and then a layered closure prevents hematoma postoperatively. |
ACL, anterior cruciate ligament; PCL, posterior cruciate ligament.
Patient Evaluation
Diagnosis of chondral injuries of the patella should start with the clinical examination, with evidence of patellar grinding, mechanical locking, and audible crepitation indicative of a probable chondral injury of the patella. Radiographic assessment and diagnostic imaging should include sunrise views to assess for patellofemoral joint space narrowing and osteophytes and magnetic resonance imaging to assess for any chondral pathology (Fig 1).
Fig 1.
Preoperative magnetic resonance imaging (MRI) of an axial (A) and coronal (B) view of a right knee. The heightened signal intensity in the mid to lateral facet of the patella with edema present inferior to the patella is indicative of an osteochondral defect present (white arrows, white circles). The increased signal intensity in the subchondral bone is indicative of subchondral cystic changes. The approximate size of the defect was measured at 10 mm in diameter, both proximal to distal and medial to lateral. Clinical examination revealed moderate patellofemoral crepitation but no instability indicative of a medial patellofemoral ligament tear.
Anesthesia and Positioning
The patient is supine on the operating table and induced under general anesthesia. An examination under anesthesia is performed to confirm the clinical findings. A high-thigh tourniquet is placed on the surgical leg. The surgical leg is placed in an extremity holder (Mizho OSI), and the patient is administered cefazolin for prophylaxis against infection.
Arthroscopy
Anteromedial and anterolateral parapatellar portals are made, and the camera is inserted into the joint. The knee is insufflated with normal saline, and the suprapatellar pouch, lateral and medial gutters, and intra-articular surfaces of both compartments are assessed. The root and ramp areas of the medial and lateral menisci are palpated with a probe to evaluate attachment areas (Fig 2). Next, the integrity of the anterior cruciate ligament and the posterior cruciate ligament attachments are confirmed, ensuring the ligaments are taut. Finally, the chondral defect is identified on the patella, and the size of the defect is approximated. A probe is used to establish the margins of the defect based on the integrity of the cartilage, observing if any delamination has occurred (Fig 3). A defect size of 10 to 12 mm is often the upper size limit for an OAT procedure.
Fig 2.
Right knee arthroscopic view of the lateral (A) and medial (B) meniscus from the anterolateral parapatellar portal. The lateral and medial root attachments are palpated to confirm they are intact (white arrows). (LFC, lateral femoral condyle; MFC, medial femoral condyle; PHLM, posterior horn of lateral meniscus; PHMM, posterior horn of medial meniscus.)
Fig 3.
Right knee arthroscopic view from the anterolateral portal of the osteochondral lesion on the patella. Any chondral flaps or loose bodies (A) are removed using a shaver, and the margins of the lesion are probed to determine if any delamination has occurred (B).
Approach and Medial Arthrotomy
An anterior midline incision is made 6 cm proximal to the superior pole of the patella to just distal to the tibial tubercle, followed by a medial parapatellar arthrotomy separating the vastus medialis oblique and the quadriceps tendon (Fig 4). Once the extensor mechanism is isolated and the exposure is complete, a Z retractor and a penetrating towel clip are used to retract the patella laterally in an everted position. The cartilage defect is identified, and the diameter is measured to determine the size of the autograft transfer needed. Once the margins are delineated, a surgical marking pen is used to outline the borders to ensure all of the defect margins are resurfaced (Fig 5).
Fig 4.
With the patient in the supine position, a right knee anterior midline incision should be made 6 cm proximal to the superior pole of the patella to just distal to the tibial tubercle, which exposes the extensor mechanism (A). Next, a medial parapatellar arthrotomy separating the vastus medialis oblique and the quadriceps tendon is performed so the patella and the donor site on the superolateral trochlea can be exposed (B).
Fig 5.
Right knee anterior view of the focal osteochondral defect of the everted patella (A) with the patient in supine position. Once the exposure of the patella is complete, a Z retractor and a penetrating towel clip are used to retract the patella and evert the patella laterally. The defect is identified (black circle), and the diameter is measured to determine the desired size of the donor site plug that is subsequently harvested from a lesser weightbearing area of the knee (B). Once the margins were established and we determined our calculated diameter of 10 mm was accurate, a surgical marking pen was used to outline the defect on each border to ensure coverage of the resurfacing process (C).
Defect Debridement and Donor Site Harvest
If chondral flaps were not completely removed with the shaver during arthroscopy, they can now be removed. Reaming of the defect begins by establishing the center and placing a guide pin at this point. This is overreamed with an autograft OATS (Osteochondral Autograft Transfer System) Recipient Site reamer (Arthrex, Naples, FL) to a desired depth of 13 mm, with caution to avoid iatrogenic heat necrosis during reaming. A series of rongeurs, blades, and pick-ups are used to remove the remaining reaming fragments (Fig 6).
Fig 6.
Right knee anteromedial view of the debridement of the focal osteochondral defect of the patella with the patient in the supine position. (A) The center of the patellar cartilage defect is identified, and a guide pin is drilled into the center of the defect. (B) A 10-mm-diameter OATS (Osteochondral Autograft Transfer System) Recipient Site reamer (Arthrex) is used to ream 13 mm deep, exposing the subchondral surface. (C) A series of rongeurs, blades, and pick-ups are used to remove the reaming fragments and confirm that the margins of the recipient site are flush and prepared for the press fitting of the autograft donor plug.
Attention is now brought to the harvest site for the autograft, and the previously measured diameter of the defect is used to match the diameter of the autograft plug. The Tube Harvester (Arthrex) is inserted perpendicular to the joint to avoid prominence within the graft. A 13-mm-deep osteochondral plug is taken from a lesser articulating portion of the superolateral trochlear groove by malleating down the harvester to the desired depth (Fig 7). The harvester is removed, alternating the harvester in 90° turns clockwise and 90° counterclockwise, and the OAT graft is ready for final transplantation into the patella.
Fig 7.
Right knee anterior view with the patient in the supine position of the osteochondral autograft transplantation (OAT) Tube Harvester (Arthrex). After the location of the donor site is confirmed on a lesser articulating chondral surface of the knee (superolateral trochlea in this case), the harvester is placed perpendicular (A) to the joint surface to avoid prominence within the graft, and a 10-mm-diameter and 13-mm-deep donor osteochondral plug is taken (black arrow). The harvester is carefully spun, alternating 90° clockwise and 90° counterclockwise, to remove the plug. The OAT is now ready for final transplantation into the patella, and clearance of the exposed recipient site is confirmed before the removal of the guide pin (B).
Osteochondral Autograft Transplantation
The pin at the center of the patella is removed from the defect site, and suction is used a final time to remove any small loose bodies. The OAT Tube Harvester (Arthrex) is placed in the debrided site matching the margins and is slowly turned clockwise to deploy the plug into the patella. A towel and small impactor are then used to reduce any prominent portions of the osteochondral autograft into the recipient site to align contiguously with the patellar cartilage margins (Figs 8 and 9).
Fig 8.
Right knee anterior view of the osteochondral autograft transplantation (OAT) with the patient in the supine position. The remnant loose osteochondral bodies are removed with suction from the recipient site on the patella (A). The OAT Tube Harvester (Arthrex) is placed on the aperture of the recipient site to confirm the size of the autograft. Before gentle impaction, the T handle on the harvester is spun clockwise to advance the OAT into the recipient site on the patella (B). A towel and impactor are used to set the plug and reduce any prominent portion within the recipient site, so it sits flush on the patella (C).
Fig 9.
Right knee anterior view of the osteochondral autograft in the patella. After initial placement (A), any portion of the plug that is proud is gently impacted, ensuring that no gaps remain in the patellar cartilage defect area (B). The donor site on the superolateral trochlea (A, white arrow) required no backfill or bone grafting before closure. The medial arthrotomy is closed using No. 2 nonabsorbable sutures (Ethicon).
Final Closure
Closure begins with the medial arthrotomy, using No. 2 nonabsorbable sutures (Ethicon, Raritan, NJ). The remaining deep tissues are closed with 0 and 2-0 Vicryl (Ethicon), followed by a Monocryl stitch (Ethicon) for the superficial skin. Steri-strips are loosely applied, followed by the application of a sterile dressing, and a knee is placed in an immobilizer in full extension.
Postoperative Protocol
The patient will be nonweightbearing on the surgical limb for 6 weeks. Flexion will be limited to 60° for the first two weeks and then may increase as tolerated. This is mainly to protect the arthrotomy incision. The patient will utilize a continuous passive motion at 0° to 60° for 2 hours twice a day for 2 weeks and may gradually increase knee range of motion as tolerated.
Discussion
Patellar osteochondral lesions of the knee remain a challenge to treat. Treatment techniques for osteochondral defects of the patella have been described in concomitant pathology, utilizing allograft plugs and osteochondral drill/microfracture for marrow stimulation.7, 8, 9, 10 The use of OAT is advantageous for numerous reasons: a single-stage procedure to restore hyaline cartilage, the use of autologous tissue, and lower costs associated with the donor harvest. A retrospective study by Figueroa et al.2 analyzed outcomes of high-grade patellar chondral defects that were treated and received an OAT. A total of 26 patients were included (mean age, 28.5 years) with chondral defects averaging 180 mm2, and patients received a median of 1 autograft (range, 1-3). Imaging outcomes revealed that 92% of patients showed plug integration to adjacent bone and good cartilage characteristics comparable with adjacent cartilage. At a mid-term follow-up, most patients reported good or excellent results with symptom and activity level improvements. Regarding isolated single-plug OAT using a press-fit technique (as described in this technique), a study by Filardo et al.11 investigated the long-term outcomes of knee OAT using a plug from a lesser weightbearing area. The cohort included 15 patients with a mean follow-up of 17.5 ± 3.5 years. Functional outcomes were assessed by Lysholm, International Knee Documentation Committee, and Tegner scores, and significant improvements were observed in all metrics.
Although improved outcomes have been reported in the short and long term, this procedure is not without inherent risk factors. Donor site morbidity of OAT from a lesser weightbearing surface of the knee has been observed, resulting in mechanical locking, fibrocartilage hypertrophy necessitating surgical intervention, and persistent anterior knee pain.12 The advantages and disadvantages of this technique are presented in Table 2.
Table 2.
Advantages and Disadvantages of an Isolated Osteochondral Autograft Transplantation for a Focal Chondral Defect of the Patella
| Advantages | Disadvantages |
|---|---|
| No risk of disease transmission and no issues of viability of osteochondral allograft due to delayed implantation | Risk of donor site morbidity and residual anterior knee pain |
| Immediate osteochondral transplantation option and restoration of native biomechanics of the patellofemoral joint | Risk of donor plug and recipient site mismatch and failure to integrate into the subchondral bone |
| Lower associated cost when compared to the use of an allograft plug | Higher demand technically to harvest and donate the osteochondral plug. Poses an increased risk of iatrogenic injury to the surrounding anatomy |
Disclosures
The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: R.F.L. has received funding grants from Ossur, Smith & Nephew, Arthroscopy Association of North America, and American Orthopaedic Society for Sports Medicine; is a consultant or advisor for Ossur, Smith & Nephew, and Responsive Arthroscopy; has received travel reimbursement from Smith & Nephew; has received speaking and lecture fees from Foundation Medical, LLC; and has a patent with royalties paid to Ossur. All other authors (E.P.S., L.V.T., M.T.R., D.R.L.) declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Supplementary Data
This is a technique video describing an isolated osteochondral autograft transplantation for a focal chondral defect of the patella. Shown here are the senior author’s disclosures. The patient is placed in the supine position on the operating table and induced under general anesthesia. An examination under anesthesia is performed to confirm the clinical findings. Anterolateral and anteromedial parapatellar portals are made, the arthroscope is inserted into the joint, and the knee is insufflated with normal saline. The suprapatellar pouch, lateral and medial gutters, and cruciate ligaments are assessed. The root and ramp areas of the medial and lateral menisci are palpated with a probe to evaluate attachment areas. Attention is then brought to the chondral defect previously identified on the patella, and the size of the defect is approximated. A probe is used to establish the margins of the defect based on the integrity of the cartilage, observing if any delamination is present. Defects of 10 to 12 mm are the upper size limit for osteochondral autograft transplantation (OATS) procedures. An anterior midline incision is made 6 cm proximal to the superior pole of the patella to just distal to the tibial tubercle. A medial parapatellar arthrotomy is then made, separating the vastus medialis oblique and the quadriceps tendon. The chondral defect of the patella is once again identified, and the diameter is calculated by measuring the margins both proximal to distal and medial to lateral. Once the extensor mechanism is isolated, a Z retractor and a penetrating towel clip are used to retract the patella laterally in an everted position. Once the margins are delineated, a surgical marking pen is used to outline the borders to ensure all of the defective margins are resurfaced. The cartilage defect diameter is used to measure the size of the autograft transplant needed from a lesser articulating surface. Any remaining chondral flaps are removed, and a guide pin is placed in the center of the defect. This is then overreamed with an autograft OATS Recipient Site reamer to a depth of 13 mm. Irrigation with cold saline may be used to avoid iatrogenic heat necrosis during reaming. A series of rongeurs, blades, and pick-ups are used to remove the excess reaming fragments. Attention is now brought to the autograft harvest site on the superolateral trochlear groove. The Tube Harvester (Arthrex) is inserted perpendicular to the joint to avoid graft prominence. A 13-mm-deep osteochondral plug is taken from the lesser articulating cartilage by malleating down the harvester to the desired depth. The harvester is then removed, alternating in turns 90° clockwise and counterclockwise while elevating until the autograft is completely removed. The guide pin at the center of the patella is removed, and suction is used a final time to remove any small loose bodies in the defect site. The Tube Harvester is placed in the debrided site and is slowly turned clockwise to deploy the plug into the patella. A towel and small impactor are then used to reduce any prominent portions of the osteochondral autograft into the recipient site until it is flush with the patellar cartilage margins. The medial arthrotomy is then closed using No. 2 nonabsorbable sutures. Confirmation of smooth patellar tracking is validated a final time before closure. The remaining deep tissues are closed with 0 and 2-0 Vicryl followed by a Monocryl stitch for the skin.
References
- 1.Hjelle K., Solheim E., Strand T., Muri R., Brittberg M. Articular cartilage defects in 1,000 knee arthroscopies. Arthroscopy. 2002;18:730–734. doi: 10.1053/jars.2002.32839. [DOI] [PubMed] [Google Scholar]
- 2.Figueroa D., Calvo Rodriguez R., Donoso R., Espinoza J., Vaisman A., Yanez C. High-grade patellar chondral defects: Promising results from management with osteochondral autografts. Orthop J Sports Med. 2020;8 doi: 10.1177/2325967120933138. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Huberti H.H., Hayes W.C. Patellofemoral contact pressures. The influence of q-angle and tendofemoral contact. J Bone Joint Surg Am. 1984;66:715–724. [PubMed] [Google Scholar]
- 4.Donoso R., Figueroa D., Espinoza J., Yanez C., Saavedra J. Osteochondral autologous transplantation for treating patellar high-grade chondral defects: A systematic review. Orthop J Sports Med. 2019;7 doi: 10.1177/2325967119876618. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Migliorini F., Baroncini A., Bell A., Weber C., Hildebrand F., Maffulli N. Surgical strategies for chondral defects of the patellofemoral joint: A systematic review. J Orthop Surg Res. 2022;17:524. doi: 10.1186/s13018-022-03419-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Oeding J.F., Dancy M.E., Fearington F.W., et al. Autologous osteochondral transfer of the knee demonstrates continued high rates of return to sport and low rates of conversion to arthroplasty at long-term follow-up: A systematic review. Arthroscopy. 2024;40:1938–1949. doi: 10.1016/j.arthro.2023.11.026. [DOI] [PubMed] [Google Scholar]
- 7.Stone J.A., Shoemaker E.P., Tollefson L.V., Slette E.L., Jacobson N.J., LaPrade R.F. Concomitant medial patellofemoral ligament reconstruction, tibial tubercle osteotomy, trochleoplasty, and osteochondral autograft transfer to the patella. Arthrosc Tech. 2024;14 doi: 10.1016/j.eats.2024.103299. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Ferrari M.B., Sanchez G., Chang A., Sanchez A., Ellera Gomes J.L., Provencher M.T. Osteochondral allograft transplantation for treatment of focal patellar osteochondral lesion. Arthrosc Tech. 2017;6:e907–e912. doi: 10.1016/j.eats.2017.02.025. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Calvo R., Figueroa D., Figueroa F., Bravo J., Contreras M., Zilleruelo N. Treatment of patellofemoral chondral lesions using microfractures associated with a chitosan scaffold: Mid-term clinical and radiological results. Cartilage. 2021;13:1258S–1264S. doi: 10.1177/19476035211011506. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Dekker T.J., Kennedy M.I., Grantham W.J., DePhillipo N.N., LaPrade R.F. Patellar fresh osteochondral allograft transplantation. Arthrosc Tech. 2019;8:e851–e854. doi: 10.1016/j.eats.2019.03.025. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 11.Filardo G., Kon E., Di Matteo B., Di Martino A., Marcacci M. Single-plug autologous osteochondral transplantation: Results at minimum 16 years' follow-up. Orthopedics. 2014;37:e761–e767. doi: 10.3928/01477447-20140825-51. [DOI] [PubMed] [Google Scholar]
- 12.LaPrade R.F., Botker J.C. Donor-site morbidity after osteochondral autograft transfer procedures. Arthroscopy. 2004;20:e69–e73. doi: 10.1016/j.arthro.2004.06.022. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
This is a technique video describing an isolated osteochondral autograft transplantation for a focal chondral defect of the patella. Shown here are the senior author’s disclosures. The patient is placed in the supine position on the operating table and induced under general anesthesia. An examination under anesthesia is performed to confirm the clinical findings. Anterolateral and anteromedial parapatellar portals are made, the arthroscope is inserted into the joint, and the knee is insufflated with normal saline. The suprapatellar pouch, lateral and medial gutters, and cruciate ligaments are assessed. The root and ramp areas of the medial and lateral menisci are palpated with a probe to evaluate attachment areas. Attention is then brought to the chondral defect previously identified on the patella, and the size of the defect is approximated. A probe is used to establish the margins of the defect based on the integrity of the cartilage, observing if any delamination is present. Defects of 10 to 12 mm are the upper size limit for osteochondral autograft transplantation (OATS) procedures. An anterior midline incision is made 6 cm proximal to the superior pole of the patella to just distal to the tibial tubercle. A medial parapatellar arthrotomy is then made, separating the vastus medialis oblique and the quadriceps tendon. The chondral defect of the patella is once again identified, and the diameter is calculated by measuring the margins both proximal to distal and medial to lateral. Once the extensor mechanism is isolated, a Z retractor and a penetrating towel clip are used to retract the patella laterally in an everted position. Once the margins are delineated, a surgical marking pen is used to outline the borders to ensure all of the defective margins are resurfaced. The cartilage defect diameter is used to measure the size of the autograft transplant needed from a lesser articulating surface. Any remaining chondral flaps are removed, and a guide pin is placed in the center of the defect. This is then overreamed with an autograft OATS Recipient Site reamer to a depth of 13 mm. Irrigation with cold saline may be used to avoid iatrogenic heat necrosis during reaming. A series of rongeurs, blades, and pick-ups are used to remove the excess reaming fragments. Attention is now brought to the autograft harvest site on the superolateral trochlear groove. The Tube Harvester (Arthrex) is inserted perpendicular to the joint to avoid graft prominence. A 13-mm-deep osteochondral plug is taken from the lesser articulating cartilage by malleating down the harvester to the desired depth. The harvester is then removed, alternating in turns 90° clockwise and counterclockwise while elevating until the autograft is completely removed. The guide pin at the center of the patella is removed, and suction is used a final time to remove any small loose bodies in the defect site. The Tube Harvester is placed in the debrided site and is slowly turned clockwise to deploy the plug into the patella. A towel and small impactor are then used to reduce any prominent portions of the osteochondral autograft into the recipient site until it is flush with the patellar cartilage margins. The medial arthrotomy is then closed using No. 2 nonabsorbable sutures. Confirmation of smooth patellar tracking is validated a final time before closure. The remaining deep tissues are closed with 0 and 2-0 Vicryl followed by a Monocryl stitch for the skin.