Carboplasty, a Minimally Invasive Procedure for Knee Osteoarthritis: Surgical Technique and Clinical Evidence : Techniques in Orthopaedics

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Carboplasty, a Minimally Invasive Procedure for Knee Osteoarthritis: Surgical Technique and Clinical Evidence

Madrazo-Ibarra, Antonio MD*; Kolin, David A. BA, MSc*; Hunter, Tracey BS*; Ogyaadu, Joseph A. MD; Duah, Henry O. MPH; Tutu, Henry O. MSc; Bandoh, Anthony MD; Nutsuklo, Prudence MD§; Boachie-Adjei, Kwadwo BS; Carroll, Kaitlin M. BS; Vad, Amoli*; Zhao, Eric; Vad, Vijay B. MD*

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Techniques in Orthopaedics 38(2):p 102-105, June 2023. | DOI: 10.1097/BTO.0000000000000615
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Knee osteoarthritis (OA) is an incapacitating disease affecting ~16% of adults worldwide.1 This number is destined to increase because of the growing elder population and obesity rates. Despite the advances in scientific knowledge and biological treatments in the field of orthopedics, there is still no effective treatment for OA. A new treatment targeting the origin of OA would help stop or delay the progression of the disease, preventing the need for total knee replacements, and the risks and costs related to surgery.

The concept of OA being a pure cartilage degeneration has shifted to a more general concept that encompasses the joint as a whole.2 The osteochondral unit, which includes the superficial articular cartilage, the bone-cartilage interface (BCI) (calcified cartilage), and the subchondral bone, is now suggested as the primary responsible for OA.3 The subchondral bone allows adequate sedimentation to the underlying cartilage, the superficial articular cartilage permits a smooth glide of the femur, tibia, and patella; and the BCI serves as a communication bridge between the subchondral bone and the superficial articular cartilage.3,4 Approximately 50% of the nutrition that articular cartilage receives comes from the subchondral bone vessels, passes through the BCI, and reaches the superficial cartilage.3 Whenever one of these components of the osteochondral unit is affected, the others are affected as well. For this reason, an effective treatment for OA should address alterations in all 3 components, the subchondral bone, the BCI, and the superficial articular cartilage.

Carboplasty is a new treatment that involves the application of bone marrow aspirate into the BCI and intra-articularly. Studies have demonstrated that Carboplasty is an effective technique in relieving pain and improving function in patients with refractory knee OA and bone edema by magnetic resonance imaging.5 (Antonio Madrazo-Ibarra et al, unpublished data, 2022) However, a detailed study explaining how to perform the procedure has not been published. Therefore, we decided to carry out this technique description article to allow other physicians around the world to replicate the procedure. In this study, we will describe the Carboplasty technique and give the 1-year experience after performing the technique on 13 patients with knee OA.



Carboplasty is indicated for patients with symptomatic knee OA and evidence of bone edema by magnetic resonance imaging who stopped improving with conservative treatments such as nonsteroidal anti-inflammatories, acetaminophen, and/or physical therapy.


Carboplasty is contraindicated in patients with active joint or skin infection of the knee, patients with a mechanical deformity that deviates the mechanical axis >10 degrees away from the neutral line (measured on a full weight-bearing anteroposterior view), patients with an hematologic neoplasia, and patients with known allergies to heparin, calcium gluconate, or lidocaine. Although not a contraindication, patients with Kellgren and Lawrence grade IV OA by x-rays have shown less improvement after the procedure.


This procedure must be performed under intravenous sedation and with fluoroscopic guidance. The required equipment is a 22-gauge needle, a 10 mL syringe, a 3 mL syringe, 1 mL heparin (1000 units/mL), 2 mL3 calcium gluconate (100 mg/1 mL), the percutaneous cartilage bone interface optimization system (PeCaBoo) (Vad Scientific LLC) (Fig. 1), a 15-blade scalpel, and a sterile marking pen. Patients are placed on the surgical table in a supine position. The C-arm is brought from the contralateral unaffected side and placed in the correct position to have a full view of the knee joint (distal femur and proximal tibia) that is going to be treated. The knee is prepped and draped in the standard manner, making sure that both the tibial tubercle and knee joint can be intervened. Four areas are marked using the sterile marking pen, 1 on the tibial tubercle (to obtain the tibial marrow aspirate), 1 on the femoral condyle that is going to be treated, 1 on the ipsilateral tibial plateau, and finally 1 medially for intra-articular joint access.

Percutaneous cartilage bone interface optimization (PeCaBoo) system. The PeCaBoo system allows obtaining and delivering bone marrow aspirate easily. The handle (blue) can be removed and used to tap the PeCaBoo system to assure an adequate fixation to the bone. When the handle is removed, a syringe can be attached to the nonsharp end of the PeCaBoo system to obtain or deliver the bone marrow aspirate.

Tibial Marrow Aspirate

Preload a 10 mL syringe with 1 mL of heparin. The previously marked sites are blocked using 1% lidocaine chloride before intervention. A 1-cm incision is performed on the skin over the tibial tubercle using a 15-blade scalpel. The PeCaBoo system is introduced in the incision and advanced all the way to the bone. Once on the bone, the handle is removed and the PeCaBoo system is carefully banged with the handle until the tip of the PeCaBoo feels firmly fixed into the bone. Remove the tap on the PeCaBoo system and attach the preloaded syringe to it (Fig. 2). Pull the syringe plunger back until 8 cm3 of bone marrow are obtained. Turning the PeCaBoo system clockwise for every cubic centimeter of bone marrow obtained will facilitate its extraction.

Tibial marrow aspirate. Physician obtaining tibial marrow aspirate from the tibial tubercle of the left knee using the percutaneous cartilage bone interface optimization system.


Preload a 3 mL syringe with 2 mL of calcium gluconate. A 1-cm incision is made over the skin in the marked areas of the femoral condyle and the tibia using a 15-blade scalpel. The PeCaBoo system is introduced through the incision over the femoral condyle, perpendicular to the leg axis, and all the way up to the bone. Once in the cortical bone, the PeCaBoo system is carefully tapped until the tip is in the BCI, which is in the distal border of the femoral condyle, just where the cartilage meets the subchondral bone (Fig. 3). Make sure that the PeCaBoo system is placed in the area of greatest cartilage loss and/or bone edema in the subchondral bone as observed in the presurgical magnetic resonance imaging. Once in the correct position, attach the syringe with the tibial marrow aspirate to the PeCaBoo system and inject 2 cm3 of the marrow aspirate. Detach the marrow aspirate syringe and attach the calcium gluconate syringe. Inject 1 mL of calcium gluconate to the BCI. By turning the PeCaBoo system counterclockwise, remove the device from the femoral condyle. Repeat the procedure in the ipsilateral tibial plateau, making sure that the 2 mL of tibial aspirate is injected into the area or greater cartilage loss and/or bone edema.

Carboplasty. Carboplasty performed in the lateral condyle of the left knee. The image shows a left knee under fluoroscopy. The percutaneous cartilage bone interface optimization system is introduced in the bone-cartilage interface to deliver the bone marrow aspirate.

The remaining 6 mL in the syringe containing the tibial marrow are injected intra-articularly. Attach the 22-gauge needle to the syringe that contains the tibial marrow aspirate. Introduce the needle in the previously marked spot for medial intra-articular knee intervention, while gently aspirating until synovial fluid enters the syringe. Once in the knee joint, inject the 6 mL of tibial marrow. Apply a bandage over every skin incision.


Patients are instructed not to exercise for 2 days after the intervention. Starting day 3 postprocedure, patients can use a stationary bike for 30 minutes daily, followed by 15 minutes of cryotherapy. Complete return to prior activity level is permitted after 1 month.


The study was approved by the local ethics committee and the internal review board at FOCOS Orthopaedic Hospital, Accra, Ghana. Written informed consent was obtained from all patients before enrollment. Thirteen patients underwent Carboplasty for knee OA and were clinically evaluated after 3, 6, and 12 months using patient-reported outcome measures including the Veterans RAND 12 Item Health Survey (VR-12) (score represents standard deviations away from the average population; a greater number means worst health), the visual analog scale for knee pain (0 to 100, 0=no pain and 100=worst pain), the Western Ontario and McMaster University Osteoarthritis Index (0 to 100, 0=no symptoms and 100=more symptoms), and the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (0 to 100, 0=total knee disability and 100=perfect knee health). Patients had a mean age of 56.5 years (range: 39 to 80), a mean body mass index (BMI) of 33.7 kg/m2 (range: 24.0 to 44.5), and 11 (84.6%) were female. Patients showed a statistically significant clinical improvement at 3 and 6 months in all PROMs compared with baseline, and in Veterans RAND 12 Item Health Survey and Western Ontario and McMaster University Osteoarthritis Index at 12 months posttreatment (Table 1). Despite no statistically significant differences were observed in visual analog scale and Knee Injury and Osteoarthritis Outcome Score for Joint Replacement at 12 months, both scores were numerically better than baseline scores, suggesting a time dependent effect. No adverse events were reported.

TABLE 1 - Patient-reported Outcome Measures
Score (95% CI) P *
 Baseline 2.9 (2.6-3.3)
 3 mo 1.9 (1.4-2.3) <0.001
 6 mo 2.1 (1.6-2.5) 0.001
 1 y 2.4 (1.9-2.9) 0.022
 Baseline 62.5 (41.7-83.4)
 3 mo 29.5 (18.4-40.5) 0.001
 6 mo 36.9 (22.0-51.7) 0.026
 1 y 51.2 (35.9-66.4) 0.560
 Baseline 45 (28.0-61.0)
 3 mo 14 (5.0-23.0) <0.001
 6 mo 20 (8.0-33.0) 0.002
 1 y 23 (7.0-40.0) 0.006
 Baseline 51.6 (41.7-61.5)
 3 mo 77.2 (69.0-85.4) 0.001
 6 mo 73.6 (68.2-79.0) 0.007
 1 y 67.8 (59.3-76.4) 0.122
All data are expressed as mean (95% CI) unless otherwise specified.
*P-value compared with baseline.
KOOS JR indicates Knee Injury and Osteoarthritis Outcome Score for Joint Replacement; VAS, visual analog scale for knee pain; VR-12, Veterans RAND 12 Item Health Survey; WOMAC, Western Ontario and McMaster University Osteoarthritis index.


Because of the minimally invasive nature of carboplasty, complications are relatively rare. A possible complication could be drilling too far in the BCI with the PeCaBoo system and completely perforating articular cartilage. This may be prevented by introducing the PeCaBoo system horizontally, perpendicular to the lower extremity axis. Superficial cutaneous nerves such as the saphenous nerve and its infrapatellar branch can be injured when addressing the tibia or the femoral condyle medially. Infection of the incisions may be prevented by performing everything under sterile conditions and adequately cleaning the surgical area. As patients are allowed to walk immediately after the procedure, the risk of thromboembolic events is low. However, an adequate presurgical evaluation by the anesthesia team may detect patients at risk and take additional measures when needed.


Carboplasty is a simple technique trying to address a complex pathology such as OA. The current study shows a brief example of the outcomes of the technique in a small cohort of patients. Most of the patients included in this study were around the sixth and seventh decade of life and had a higher BMI, which could explain the limited benefit of carboplasty after 12 months. However, this carboplasty should ideally be indicated in patients 30 to 65 years of age, with a BMI <30 kg/m2, and a grade II to III OA. Prior surgeries such as meniscectomies, meniscal repairs, or ligament reconstructions should not be a limitation for the procedure, but further studies are needed to see the impact of these prior surgeries on the effectiveness of carboplasty.


Patients with knee OA showed improved clinical scores after carboplasty in the short term. The combination of mechanical decompression and bone marrow aspirate is promising and worthy of further research, hoping to have simple and effective treatment for OA.


  • Minimally invasive procedure with the potential to treat OA.
  • Carboplasty is affordable, simple, quick, and with small downtime.
  • No major adverse events have been reported.


Clinical outcomes are not so promising in patients with major mechanical deformity, grade IV OA, and an increased body mass index.


The authors thank Alexa Müller, Nikhil Vad, and Arnav Barve for the contribution to the study, as well as the Vad Foundation for the financial support.


1. Cui A, Li H, Wang D, et al. Global, regional prevalence, incidence and risk factors of knee osteoarthritis in population-based studies. EClinicalMedicine. 2020;29–30:100587.
2. Hunter DJ, Bierma-Zeinstra S. Osteoarthritis. Lancet. 2019;393:1745–1759.
3. Findlay DM, Kuliwaba JS. Bone–cartilage crosstalk: a conversation for understanding osteoarthritis. Bone Res. 2016;4:16028.
4. Hoemann C, Lafantaisie-Favreau C-H, Lascau-Coman V, et al. The cartilage-bone interface. J Knee Surg. 2012;25:085–098.
5. Vad V, Barve R, Linnell E, et al. Knee osteoarthritis treated with percutaneous chondral-bone interface optimization: a pilot. Trial SS. 2016;07:1–12.

knee; osteoarthritis; carboplasty; bone-cartilage interface; bone marrow aspirate

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