Healio
Healio
May 01, 2008
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Osteochondral Resurfacing—Pearls and Pitfalls

Before performing unicompartmental knee arthroplasty (UKA), interim steps must be considered. Osteochondral resurfacing can reestablish the structural load-bearing surface and curvature radius to damaged and deficient areas of articular cartilage and subchondral bone.

Physiologic, histologic, and biomechanical restoration of the cartilage/bone interface requires a congruent and stable bony foundation. The osteochondral lesion affects the articular cartilage, medial femoral condyle, and “zone of influence” surrounding the lesion.1 Contact pressures extend 2 to 3 mm around the periphery, resulting in a total affected area <6 mm surrounding the lesion, a significant factor in disease progression and patient symptomatology.

Cartilage alignment requires an opening-wedge osteotomy to create a neutral mechanical access, rather than shifting cartilage to a valgus position. Stability must be established for sufficient ligamental balance within the knee and optimal functionality in the meniscus. Surgical options include palliative procedures (eg, shaving, debridement, and lavage) reparative processes (eg, subchondral drilling and microfracture) and restorative procedures (eg, tissue transplantation, cell therapies, and synthetic and biological matrices).

The clinician will determine the treatment based on the location and size of the lesion, progressing from microfracture to osteochondral autograft, then autologous chondrocyte implantation (ACI), allograft, or realignment (Figure). Depending on the lesion size, it may also be beneficial to use biological materials such as a bioscaffold with autologous or allogeneic additives, a bioscaffold with bioactives, or cells for larger lesions, compared with metal or plastic resurfacing.

Figure: Treatment is determined based on the location and size of the lesion

Figure: Treatment is determined based on the location and size of the lesion. Reprinted with permission from Alford JW, Cole BJ. Cartilage Restoration: Techniques, outcomes, and future directions. Am J Sports Med. 2005;33(3): 443-460.

Microfractures

An 11-year, follow-up study2 reported a complex treatment regimen of nutraceuticals, viscous supplementation, and extensive release of suprapatellar adhesions that produced good results in 76% of patients. In a prospective cohort study of microfracture surgery in active patients, 67% of patients experienced a good to excellent response.3 However, a significant decrease in beneficial outcomes was reported at 18 to 24 months postoperatively; patients with low body weight or who had shorter periods (6 months or fewer) of symptoms, experienced the most favorable results.3

In a study comparing microfracture surgery with the osteochondral autograft transfer system (OATS), 52% and 96% of patients, respectively, experienced good to excellent results.4 Similar outcomes were reported when the patients returned to sports activity (52% with microfracture vs 93% with OATS).

If biomechanical integrity is not reestablished, patients will experience a reduction in improvement over time. Particularly in patients who return to high-impact activity, symptomatic pain is more likely to occur because of increased subchondral pressure within the bone.

Autologous Chondrocyte Implantation

Autologous chondrocyte implantation (ACI) requires reoperation after initial harvesting of cells. Some investigators recommend bone grafting in patients with larger defects. In a 2004 trial comparing ACI with microfracture surgery, no histologic or gross outcome differences were found between the two treatment approaches.5

In a study of soccer players who underwent articular cartilage repair, 16% returned to 80% of their preoperative level activity.6 In most patients, significant improvement was not observed until 12 to 18 months postoperatively, most likely because biomechanical integrity of the bone deep to the subchondral plate could not be reestablished.

A particular challenge in performing resurfacing procedures is reproducing the orientation of stress lines in articular cartilage, because autograft integration at the seams of the defect is often difficult to achieve.

Osteochondral Autograft Transfer System

Important factors to consider when performing an OATS procedure include autograft lesion size and location; contour, convexity, orientation, and depth of the articular cartilage; graft harvest site morbidity; the potential for hypertrophic tissue development; and a persistent “hole” that could worsen a unicompartmental problem to a bicompartmental one.

A trial of the OATS procedure in 18 patients studied the potential for hypertrophic tissue development and found persistent hypertrophic tissue and effusions at the graft harvest site for >5.5 months in more than 50% of cases (7/12).7 Reddy et al8 reported the results in 11 patients with tailored-dome, osteochondral lesions who underwent the OATS procedure, with five excellent, two good, and four poor outcomes. Postoperatively, most of the patients complained of joint instability during daily activities in the previously asymptomatic knee, resulting in persistent problems in both knee joints.

Osteochondral Allograft

Clinical experience has proven that fresh osteochondral allografts can potentially restore the functional histologic architecture of the articular surface, alleviate pain, enhance function, and prevent future arthrosis. Osteochondral allografts have been shown to result in host bone incorporation for 0.5 to 3 years and chondrocyte viability for up to 17 years. The use of bone/cartilage composite has beneficial biomechanical characteristics.

However, the potential for disease transmission from pathogens is a continuing concern. Moreover, although the long-term viability of chondrocytes has been demonstrated, the degree of bone incorporation deep to the surface remains uncertain. In most cases, a low-grade immunogenic response can potentially delay healing.

In a 2-year investigation of distal femoral resurfacing using fresh-stored osteochondral allografts, Davidson and colleagues9-17 reported good results, particularly in traumatic and osteochondritis dessicans defects. Ten additional studies on fresh osteochondral allografting were conducted, resulting in a cumulative total of 444 patients (Table). Generally, less favorable outcomes have been reported in patients with multiple or patellofemoral defects, although results in the latter category have improved.18 This may be a result of better understanding of the patellofemoral biomechanics and efforts to improve patellofemoral joint balance through tibial tubercle transfer excision of impinging plica and lateral release coupled with medial incision when indicated.

Table: Results of Fresh Osteochondral Allografting

A number of approaches to facilitate bony incorporation have been studied, most notably cryopreservation. The use of cryopreserved cartilage with dimethyl sulfoxide has been shown to stimulate angiogenesis in bone as well as to provide immune tolerance, thus reducing immunogenic load to the bone. In addition, the cryopreservation process allows tissue to be stored for extended periods.19

A New Cartilage Scaffold

To improve surgical outcomes in patients undergoing total knee arthroplasty (TKA), clinicians can use an effective synthetic cartilage scaffold matrix that meets the following requirements:

  • Biocompatibility (absence of immediate or delayed inflammatory or cytotoxic response)
  • Biodegradability (to provide biomechanical support while promoting replacement)
  • Permeability (microporosity of 50 µm/macroporosity of 150 µm to promote integration and edge adhesion)
  • Availability

The Tru-Fit plug (S-N Endoscopy, Mansfield, Massachusetts) is a preformed polymer that meets a majority of these requirements. In addition to being layered, porous, and biodegradable, the Tru-Fit design incorporates structures that stimulate cartilage ingrowth and bony integration. The alignment of this scaffold was designed to stimulate the articular cartilage, and its pattern resembles cancellous bone. Finally, this polymer features a fiber reinforcement structure that provides elasticity similar to that of natural bone, encouraging surface cartilage formation.

Patient Case History 1

Profile

The patient is a 36-year-old white man, with left knee pain and a history of partial medial meniscectomy 3 years prior. The patient is McMurray’s-positive and ACL competent.

Diagnosis

A tear in medial meniscus and a chondral lesion of the medial femoral condyle were found. After meniscus repair, an undersurface tear remained that was unlikely to heal; articular cartilage defect was beginning to propagate, with a significantly large zone of influence.

Surgical Approach

A 9 mm Tru-Fit plug was placed in the defect.

Outcome

The starburst stress-line pattern disappeared; seam integration was observed from the edges and sides, with good continuity observed at 18 months postoperatively that could not have been achieved either with an osteochondral autograft or an allograft procedure.

Patient Case History 2

Profile

The patient is a 40-year-old white man and physical education teacher, with a history of ACL reconstruction with patella fracture 25 years earlier and patella chondroplasty with loose bodies removed in 2002. The patient presented with right knee pain and a range of motion of 0°-120°; tenderness along the patellofemoral joint with eccentric loading, and significant tenderness over lateral femoral condyle.

Diagnosis

Significant defects of lateral femoral condyle and trochlear groove were found.

Surgical Approach

Two 9 mm Tru-Fit plugs were placed after 6 weeks of preoperative nutraceutical treatment with glucosamine/chondroitin/methylsulfonylmethane, and hyaluronic acid. The postoperative treatment regimen included use of Hypex brace (Hypex; Albrecht, Munich, Germany), continuous passive motion, touch-down weight-bearing, viscosupplementation, and functional conditioning programs (Gary Gray, PT, Ann Arbor, Michigan).

Outcome

The patient returned to a highly active professional lifestyle, showing significant improvement in muscle tone, degree of motion, and flexion.

The investigators’ group implanted the Tru-Fit plug in 167 patients, most frequently in those with osteochondral defects (48%), degenerative joint disease (18%), chondromalacia (15%), and osteochondral lesion (10%). The investigators reported the average cumulative improvements in patients 18 months postoperatively.

The study results showed that biological resurfacing is increasingly favored over TKA, preserves ligaments and balance within the knee, and gives patients a feeling of normalcy within the joint that may not be achieved with TKA.

References

  1. Jackson DW, Lalor PA, Aberman HM, Simon TM. Spontaneous repair of full-thickness defects of articular cartilage in a goat model. A preliminary study. J Bone Joint Surg Am. 2001; 83-A(10):1591-1592.
  2. Steadman JR, Briggs KK, Rodrigo JJ, Kocher MS, Gill TJ, Rodkey WG. Outcomes of microfracture for traumatic chondral defects of the knee: average 11-year follow-up. Arthroscopy. 2003; 19(5):477-484.
  3. Mithoefer K, Williams RJ 3rd, Warren RF, et al. The microfracture technique for the treatment of articular cartilage lesions in the knee. A prospective cohort study. J Bone Joint Surg Am. 2005; 87(9):1911-1920.
  4. Gudas R, Kalesinskas RJ, Kimtys V, et al. A prospective randomized clinical study of mosaic osteochondral autologous transplantation versus microfracture for the treatment of osteochondral defects in the knee joint in young athletes. Arthroscopy. 2005; 21(9):1066-1075.
  5. Knutsen G, Engebretsen L, Ludvigsen TC, et al. Autologous chondrocyte implantation compared with microfracture in the knee. A randomized trial. J Bone Joint Surg Am. 2004; 86-A(3):455-464.
  6. Mithoefer K, Williams RJ 3rd, Warren RF, et al. High-impact athletics after knee articular cartilage repair: a prospective evaluation of the microfracture technique. Am J Sports Med. 2006; 34(9):1413-1418. Epub 2006 May 30.
  7. Koulalis D, Schultz W, Heyden M, et al. Autologous osteochondral grafts in the treatment of cartilage defects of the knee joint. Knee Surg Sports Traumatol Arthrosc. 2004; 12(4):329-334. Epub 2003 Sep 26.
  8. Reddy S, Pedowitz DI, Parekh SG, et al. The morbidity associated with osteochondral harvest from asymptomatic knees for the treatment of osteochondral lesions of the talus. Am J Sports Med. 2007; 35(1):80-85. Epub 2006 Sep 6.
  9. Davidson PA, Rivenburgh, Rozin R. Two-year clinical, histologic, and radiographic outcomes of distal femoral resurfacing with fresh osteondral allografts. Presented at: The American Orthopaedic Society for Sports Medicine; October 2005; Keystone, CO.
  10. Ghazavi MT, Pritzker KP, Davis AM, et al. Fresh osteochondral allografts for post-traumatic osteochondral defects of the knee. J Bone Joint Surg Br. 1997; 79(6):1008-1013.
  11. Meyers, MH, Akeson W, Convery FR, Resurfacing of the knee with fresh osteochondral allograft. J Bone Joint Surg am, 1989; 71(5):704-713.
  12. Chu CR, Convery FR, Akeson WH, et al. Articular cartilage transplantation. Clinical results in the knee. Clin Orthop Relat Res. 1999; (360):159-168.
  13. Aubin PP, Cheah HK, Davis AM, Gross AE. Long-term follow-up of fresh femoral osteochondral allografts for posttraumatic knee defects. Clin Orthop Relat Res. 2001; (391 suppl):S318-S327.
  14. Garrett JC. Fresh osteochondral allografts for treatment of articular defects in osteochondritis dissecans of the lateral femoral condyle in adults. Clin Orthop Relat Res. 1994; (303):33-37.
  15. Bugbee WD, Fresh osteochondral allografts. Knee Surgery. 2002; 15(3): 191-195.
  16. Bugbee WD, Fresh osteochondral grafts for the knee. Techniques in Knee Surgery, 2004; 3(2):68-76.
  17. Jamali A, Bugbee WD, Chu C, et al. Fresh osteochondral allografts of the patellofemoral joint. Paper #177. Presented at the AAOS 68th Annual Meeting, February 2001; San Francisco, CA.
  18. Jamali AA, Emmerson BC, Chung C, Convery FR, Bugbee WD. Fresh osteochondral allografts. Clin Orthop Relat Res. 2005; (437):176-185.
  19. Egli RJ, Wingenfeld C, Hölzle M, et al. Histopathology of cryopreserved bone allo- and isografts: pretreatment with dimethyl sulfoxide. J Invest Surg. 2006 Mar-Apr;19(2):87-96.

Author

Dr Caborn is professor of orthopedic surgery, University of Louisville, Louisville, Kentucky.

Dr Caborn is a consultant for Arthrex, Cryolife, and Zimmer.