Microdrilling Surgery Augmented With Intra-articular Bone Marrow Aspirate Concentrate, Platelet-Rich Plasma, and Hyaluronic Acid: A Technique for Cartilage Repair in the Knee

Abstract

The ideal treatment of large full-thickness chondral lesions in the knee, especially “kissing lesions” and osteoarthritis, has not been determined. Microdrilling surgery augmented with injections of peripheral blood stem cells and hyaluronic acid has been used to treat patients with a wide range of articular cartilage disease including patients with bipolar lesions and joint space narrowing. Excellent results in this difficult patient population have been reported, and second-look biopsy has shown repair tissue very similar to native hyaline cartilage. Because of Food and Drug Administration regulations, this technique is not currently allowed in the United States. We describe a Food and Drug Administration–compliant modification of this technique using microdrilling augmented with intra-articular bone marrow aspirate concentrate, platelet-rich plasma, and hyaluronic acid.

The ideal treatment of large full-thickness chondral lesions in the knee, especially “kissing lesions,” has not been determined. Most surgeons believe that conventional treatment such as microfracture is relatively contraindicated for bipolar cartilage damage and for lesions greater than 4 cm². The repair tissue formed by microfracture is primarily fibrocartilage, which is known to be inferior to hyaline cartilage.¹ Saw et al.2, 3 have reported on a technique that combines arthroscopic microdrilling with injections of peripheral blood stem cells (PBSCs) and hyaluronic acid (HA). Second-look biopsy has shown tissue with histology very similar to native hyaline cartilage as well as excellent clinical scores in a difficult patient population including patients with bipolar and diffuse cartilage damage.2, 3 Food and Drug Administration (FDA) regulations do not currently allow use of PBSCs in the knee.⁴ We describe an FDA-compliant technique that combines arthroscopic microdrilling with postoperative injections of bone marrow aspirate concentrate (BMAC), platelet-rich plasma (PRP), and HA to treat full-thickness chondral damage including large bipolar lesions.

Technique

BMAC and PRP Preparation

After appropriate general anesthesia, patients are turned into the lateral decubitus position. The posterior pelvic region is prepared and draped. A tiny (1- to 2-mm) stab incision is created over the posterior superior iliac spine ipsilateral to the operative knee. A 15-gauge Illinois bone marrow needle (CareFusion, McGaw Park, IL) with the lower sleeve removed is positioned on the central posterior superior iliac spine and tapped approximately 1 cm deep with a mallet (Fig 1A). The needle stylus is then removed. A 20-mL catheter-tip syringe prefilled with 100 U of heparin (100 U/mL) is attached to the back of the needle, and negative pressure is applied to aspirate 15 to 20 mL of bone marrow. The syringe is then detached, capped with an 18-gauge needle, and inverted several times to ensure adequate mixing.

Fig 1.

Bone marrow aspiration and filtration. (A) With the patient positioned lateral, a 15-gauge Illinois bone marrow needle with the lower sleeve removed is inserted into the central posterior superior iliac spine. Fifteen to twenty milliliters of bone marrow is drawn into a 20-mL syringe prefilled with 100 U of heparin. (B) The syringe is capped with an 18-gauge needle, and the bone marrow–heparin mixture is injected through a coupler into a 150-mL polyvinyl chloride transfer bag. (C) The contents are run through a 210-μm filter to remove any bony particulates. (D) The filtered bone marrow is divided between two 10-mL red-top serum tubes.

The mixture is injected through a coupler (GD896894; Fenwal, Lake Zurich, IL) into a 150-mL polyvinyl chloride transfer bag (140902; Charter Medical, Winston-Salem, NC) (Fig 1B). The contents are then run through a 210-μm filter (11141-48; Hospira, Lake Forest, IL) in a sterile closed system to remove any clots and bony particulates (Fig 1C) and divided between two 10-mL serum tubes (BD Vacutainer [366441]; Becton Dickinson, Franklin Lakes, NJ) (Fig 1D). The tubes are centrifuged for 10 minutes at 1,300g (VanGuard V6500; Hamilton Bell, Montvale, NJ) (Fig 2A). The tubes are carefully uncapped, and a 10-mL Luer-Lok syringe (Becton Dickinson) with an 18-gauge 3.5-inch spinal needle is used to aspirate the buffy coat and some plasma from both tubes (Fig 2B). Usually 3 to 5 mL of BMAC is obtained in this manner. This mixture is then passed onto the sterile field.

Fig 2.

Bone marrow aspirate concentrate (BMAC) and platelet-rich plasma (PRP) preparation. (A) The red-top tubes containing the filtered bone marrow are centrifuged for 10 minutes at 1,300g. (B) After centrifugation, the tubes are carefully uncapped, and a spinal needle is used to aspirate the buffy coat and some plasma from both tubes, yielding 3 to 5 mL of BMAC. (C) The Biomet GPS III system is used to obtain 7 mL of PRP from 55 mL of whole blood. (D) The 3 biologic components, ready to be combined for a knee injection: 25 mg of hyaluronic acid (HA), PRP, and BMAC.

The patient is positioned supine while the BMAC is prepared. While the patient is being positioned, anesthesia personnel obtain blood through venipuncture to prepare PRP using the Biomet GPS III platelet concentration system (Biomet Biologics, Warsaw, IN) (Fig 2C). Per instructions in this system, 52 mL of blood is combined with 8 mL of anticoagulant citrate dextrose and used to generate approximately 7 mL of PRP. This is also passed onto the sterile field. The BMAC, PRP, and 25 mg of HA (Supartz; Bioventus, Durham, NC) are combined in a single 20-mL syringe for use at the conclusion of the procedure (Fig 2D).

Microdrilling Procedure

The foot of the operating room bed is dropped down 90°. The contralateral leg is fully abducted on an arm board attached to the end of the bed (Fig 3A). A tourniquet is placed on the operative leg, but it usually is not required. After preparation and draping, standard medial and lateral arthroscopy portals are established. Many of these patients have undergone multiple previous knee operations, so debridement of scar tissue is usually needed for appropriate visualization. Clinically significant meniscal pathology is addressed first. Attention is then turned to the chondral lesions. A ring curette is used to remove any remaining damaged cartilage in the full-thickness defect or defects. A No. 11 scalpel blade is often used as well to develop well-defined margins. The calcified cartilage layer is also removed using the ring curette.

Fig 3.

Surgical preparation. (A) Patient positioning for microdrilling surgery. The foot of the operating room bed is dropped down 90°. The contralateral leg is fully abducted on an arm board attached to the end of the bed. (B) A Smith & Nephew 2.9-mm mini burr is modified for drilling holes 2 mm in diameter and 7 mm deep. Seven millimeters of the protective sleeve is removed with a wire cutter to allow the burr to drill to the appropriate depth.

Microdrilling of each lesion is then performed. Drilling is performed with a 2.9-mm mini burr (3530; Smith & Nephew, London, England). The “2.9 mm” represents the diameter of the protective sleeve. The burr itself measures 2 mm. Seven millimeters of the protective sleeve is removed with a wire cutter to allow use of the burr for drilling (Fig 3B). The crimped end of the cut sleeve is then opened back up using an obturator from a 3-mm outflow cannula (720491; Smith & Nephew). Holes are drilled to a depth of 7 mm (when the remaining sleeve contacts the bone) and are placed 2 to 3 mm apart (Fig 4A). Drilling is performed slowly so that thermal damage of the bone does not occur (Table 1).

Fig 4.

Trochlea lesion in a right knee, with arthroscopic views from the anterolateral portal. (A) Lesion after debridement and drilling. The holes are 7 mm deep and placed 2 to 3 mm apart. (B) The same lesion is injected with bone marrow aspirate concentrate, platelet-rich plasma, and hyaluronic acid with an 18-gauge 3.5-inch spinal needle under arthroscopic guidance.

Table 1.

Pearls and Pitfalls

Do not use an arthroscopic leg holder because deep knee flexion is more difficult.

Use a padded Mayo stand to rest the foot on while drilling the patella.

Drill slowly with the burr and back out several times to clear bone debris and prevent thermal necrosis.

Check under the meniscus for cartilage defects. Retract the meniscus with a probe while drilling there.

Create additional mini portals as necessary to maintain perpendicular drilling.

Perform a percutaneous medial collateral ligament release when necessary to drill the tibia. (Do not resort to a microfracture awl.)

Bear in mind that performing a lateral release greatly improves access for patella drilling.

Use a tenaculum clamp on the patella for easier patella positioning and stability while drilling.

When injecting buffered lidocaine for bone marrow aspiration, infiltrate the periosteum in an area approximately 2 cm in diameter to minimize discomfort.

Begin early isometric loading of the patellofemoral joint after patellofemoral joint drilling.

Advise patients that they should not expect improvement from baseline until 3-6 months postoperatively.

Drilling of lesions on the femoral condyles and trochlea is usually fairly straightforward, with small accessory portals required to ensure perpendicular drilling. A spinal needle is always placed first to determine the proper placement of these portals. Lesions of the patella and tibial plateau are more difficult to access. For the patella, especially in a tight knee, a lateral release is often necessary to be able to tilt the patella enough to drill the central ridge. A tenaculum clamp placed on the patella through tiny stab incisions greatly facilitates positioning of the patella by an assistant (Fig 5). The placement of the accessory portals for patella drilling must be posterior enough to allow drilling as perpendicular as possible. Drilling of the central ridge usually requires drilling from both the medial and lateral aspects of the knee, because any drilling of the medial side of the ridge from the lateral side, for example, will tend to “skive.” For drilling of the medial tibial plateau, we now usually perform a percutaneous release of the medial collateral ligament in the method described by Fakioglu et al.⁵ The improved access allows medial tibial lesions to be more easily drilled (Video 1). Posterior tibial plateau lesions are accessed from a midcoronal portal, whereas anterior plateau lesions are accessed from an anterior portal.

Fig 5.

Microdrilling surgical technique for a medial patella facet lesion in a right knee. All arthroscopic views are from the superomedial portal with a 30° arthroscope. (A) A ring curette is used to debride the lesion and to remove the calcified cartilage layer. The curette enters the knee posteromedial to the patella. (B) Drilling of debrided lesion. Tilting the patella with a tenaculum clamp facilitates perpendicular drilling of the patella. (C) A mini shaver is used to smooth the edges of the lesion after drilling.

After all lesions are drilled, water is suctioned from the knee. An 18-gauge spinal needle is inserted percutaneously into the primary chondral lesion. All portals are closed with nylon suture. The 20-mL syringe containing the BMAC, PRP, and HA is affixed to the spinal needle, and the mixture is then injected into the knee (Fig 4B). A standard sterile dressing is applied.

Postoperative Rehabilitation

Continuous passive motion for 2 hours per day is started on postoperative day 2 and continued for 4 weeks. Patients with tibiofemoral lesions are kept partially weight bearing for 6 weeks, whereas patients with patellofemoral lesions may only bear weight as tolerated with the knee extended. Early on in physical therapy, there is a focus on isometric exercises in varying degrees of flexion to load all drilled areas. Early dynamic loading is not recommended to avoid shear injury to repair tissue. This protocol was established in accordance with previously published recommendations.² Cycling is allowed at 1 month, jogging at 9 months, and return to sport at 1 year postoperatively (Table 2).

Table 2.

Procedure and Rehabilitation Timeline

Time	Event
Day 1	Surgery and first injection of PRP, BMAC, and HA
Day 3	Start CPM and PT, partial weight bearing
Weeks 2-6	Five more weekly injections of PRP, BMAC, and HA
Week 4	Stop CPM
Week 6	Advance to weight bearing as tolerated
4 mo	Three more weekly injections of PRP, BMAC, and HA
9 mo	Return to jogging
1 yr	Three more weekly injections of PRP, BMAC, and HA
	Return to sport

BMAC, bone marrow aspirate concentrate; CPM, continuous passive motion; HA, hyaluronic acid; PRP, platelet-rich plasma; PT, physical therapy.

Postoperative Injections

Beginning 1 week postoperatively, intra-articular knee injections of BMAC, PRP, and HA are administered once per week for 5 weeks. The aspiration-injection procedure is performed in the office with the patient under local anesthesia. To minimize patient discomfort, lidocaine is buffered with 8.4% sodium bicarbonate at a lidocaine-bicarbonate ratio of 10:1. An effusion, if present, should be aspirated first. At 4 months and at 1 year postoperatively, 3 more weekly injections are performed, for a total of 12 injections including the first injection given at the time of surgery.

Discussion

Treatment of full-thickness chondral lesions of the knee with microdrilling and injections of BMAC, PRP, and HA is a technically feasible FDA-compliant modification of the technique described by Saw et al.2, 3 Biologic-augmented microdrilling has the advantage of an all-arthroscopic procedure amenable to a wide range of chondral diseases. Although we recommend 12 total bone marrow aspirations–knee injections over the course of 1 year after microdrilling surgery, we have optimized the in-office procedure to minimize surgeon time and maximize patient comfort (Table 3). Like other cartilage repair techniques, our technique is not indicated for patients with significant malalignment unless combined with an osteotomy. In addition, age over 60 years may be a relative contraindication (Table 4).

Table 3.

Advantages and Disadvantages

Advantages

The technique is applicable to a wide range of cartilage damage, including bone-on-bone arthritis.

Bone marrow processing materials are inexpensive compared with commercially available bone marrow concentration kits.

The technique is a single-surgery arthroscopic procedure.

Failure of previous cartilage restoration procedures does not seem to be a negative prognostic factor.

Disadvantages

A large number of postoperative bone marrow aspirations and knee injections are required.

Postoperative injections are not covered by insurance.

Standard insurance reimbursement for microfracture surgery is low for the time involved in treating large or multiple lesions.

Table 4.

Indications and Contraindications

Indications

Symptomatic International Cartilage Repair Society grade III or IV chondral lesions of the knee in any compartment

Treatment area up to 18 cm2 for bipolar lesions or up to 9 cm2 for unipolar lesions

Contraindications

Body mass index >35

Age >60 yr

Significant varus or valgus∗

Flexion contracture ≥10°

^∗Mechanical axis of the knee passing more than halfway from the midline of the tibia to the edge of the tibial condyle.

To date, this procedure has been performed in 40 knees, with treatment area ranging from 0.6 to 14.7 cm². On the basis of the outcomes of patients 1 to 5 years postoperatively, an upper limit of treatment area has not been determined. Although these results need to be confirmed with more patients and long-term follow-up, early outcomes are generally very good regardless of treatment area, location, or number of involved compartments. Similar to microdrilling with PBSCs described by Saw et al.,2, 3 the available data suggest that the FDA-compliant biologic-augmented microdrilling technique described in this article may be applicable to a wide range of chondral diseases.

Supplementary Data

Video 1

Biologic-augmented microdrilling. With the patient positioned lateral, 20 mL of bone marrow aspirate is collected from the posterior superior iliac spine into a syringe prefilled with 100 U of heparin. The collected marrow is run through a 210-μm filter, divided evenly between 2 serum tubes, and centrifuged. After centrifugation, a syringe attached to an 18-gauge 3.5-inch spinal needle is used to extract the buffy coat and some plasma. This procedure yields 3 to 5 mL of bone marrow aspirate concentrate (BMAC). Between 6 and 7 mL of platelet-rich plasma (PRP) is prepared from peripheral blood using the Biomet GPS III system. While the bone marrow and blood are being processed, the patient is positioned supine with the contralateral leg abducted on an arm board. During surgery, multiple holes will be drilled with a 2-mm burr. The burr must be modified before use. Seven millimeters of the protective sleeve is removed with a wire cutter to allow the burr to drill to the appropriate depth. In this case, 2 right knee central patellar lesions with a total area of 5.8 cm² will be treated. A ring curette is used to remove loose cartilage including the calcified cartilage layer. Holes are drilled 7 mm deep and 2 to 3 mm apart. Tilting the patella with the assistance of a tenaculum clamp greatly facilitates perpendicular drilling of the patella. Often, to drill lesions of the tibial plateau at the correct angle, a medial collateral ligament release may be required. After all lesions have been treated, the knee is suctioned dry and the mixture of BMAC, PRP, and 25 mg of hyaluronic acid is injected into the primary lesion. Postoperative rehabilitation consists of continuous passive motion daily for 1 month and partial weight bearing on crutches for 6 weeks.