ARTICULAR CARTILAGE: CURRENT CONCEPTS
From Boston University School of Medicine’s Evaluation and Treatment of the Injured Athlete: Sports Medicine
Update 2007
| ARTICULAR CARTILAGE IN 2007: AN OVERVIEW —Nicholas A. Sgaglione, MD, Associate Professor of Surgery,
Albert Einstein College of Medicine of Yeshiva University, Bronx, NY, and Assistant Chief of Orthopaedic
Surgery, North Shore University Hospital, Manhasset, NY
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| Take-home message: orthopaedist performing arthroscopic procedures will see treatable, pure-on-pure, grade IV,
focal, symptomatic lesions in 7% to 15% of cases; more lesions seen in knee surgery, eg, chronic anterior cruciate
ligament (ACL) cases and patellar dislocations; treat larger lesions due to edge-loading and rim stress—occur in
chondral defects >10 mm in weight-bearing zone of condyle in patients having problems with containment and
shouldering; leads to perimeter breakdown and enlargement over time; alignment also determines edge loading
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| Profile everything: from clinical approach; dynamic profile relating to activity demands; mechanism of injury
(high; low; dashboard knee); time to treatment; chronicity; confounding pathologies (meniscal attrition; alignment;
biochemical issues); lesion (bone involvement; geometric parameters); effect of treatment on natural history (early
motion; microfracture leading to limited weight-bearing and loss of thigh muscle tone); loading capabilities; age and
genomics; effect of body mass index (BMI) on alignment
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| Treatment options: debridement (essentially, “leave it alone”)
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 | Microfracture: deemed by many to be standard of treatment; although 66% of patients do well, only 44% able to return
to high-impact sports; durability in question (decline in activity scores at 2-yr mark)
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| Osteochondral autograft transfer system (OATS): plug placement—leaving too proud leads to edge-loading, causing
fibrillation and breakdown; contact pressures lowest when flush, less when countersunk, and significantly
higher when proud; take-home message—if unable to make flush, countersink plug somewhat; if one side proud
and other countersunk, aim to leave one side flush and other countersunk; graft selection—use larger grafts (6-8
mm preferable to 4-6 mm)
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| Allograft implantation: studies indicate good results in small subsets of patients using fresh cold-stored allografts;
allografts stored >21 days may have problems with chondrocyte viability and extracellular matrix
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| Autologous chondrocyte implantation (ACI): good track record; problems with periosteal hypertrophy (≤31%); investigators
found that debridement after hypertrophy produced suboptimal results
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| Concluding points: treat focal symptomatic lesions; microfracture practical (beware of age and durability issues);
OATS optimal (technically difficult); allografts future for larger lesions and more complex cases (procurement and
availability problems); ACI optimal secondary treatment (hypertrophy concerns); future—hyaline tissue; zoned
hyaline; whole-tissue graft (for bony lesions); ability to integrate native host tissue with resurfaced area; scaffolds
promising; development of cell lines and biologic factors
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| MANAGEMENT OF PARTIAL THICKNESS CARTILAGE DEFECTS —James H. Lubowitz, MD, Clinical Assistant
Professor, Department of Orthopaedic Surgery, University of New Mexico School of Medicine, Albuquerque; Director,
Taos Orthopaedic Institute, Taos Orthopaedic Institute Research Foundation, Taos Orthopaedic Institute Sports
Medicine Fellowship Training Program, Taos, NM; and Assistant Editor-in-Chief, Arthroscopy: The Journal of Arthroscopic
and Related Surgery
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| Conflicting evidence: evaluation—magnetic resonance imaging (MRI) able to assess articular surfaces of knee
but unable to clearly identify lesions; arthroscopy may not detect early stages of cartilage degeneration;
treatment—glucosamine effective, but lacking evidence of benefit; steroid infections reduce knee pain but unlikely
to last beyond 3 to 4 wk; hyaluronic acid injections relieve knee pain but not clinically effective; treatment—
mechanical debridement can improve pain and function, but does not restore normal articular surface or eliminate
functional limitations; thermal chondroplasty produces better clinical outcome than mechanical shaver, but may
cause more damage
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| Confounding variables: cartilage defects do not occur alone; concomitant pathologies include ACL problems,
meniscus, loose bodies, and multiple lesions; unclear whether improvement due to treatment of other pathologies;
isolated focal lesions rare
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| Inadequate follow-up: journals prefer 2-yr follow-up; longest case series 5 yr (30 yr ago); chondromalacia may
take decades to progress to arthritis
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| Evidence-based medicine: little exists; mostly level 4 or 5 (case series; case reports; expert opinion); speaker providing
personal opinion (level 5)
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| Evaluation: MRI findings—variable (reflecting geography, field strength, techniques, and radiologist quality);
speaker tries to read each MRI, mainly for concomitant pathology but also checking cartilage; arthroscopy—
perhaps gold standard; able to probe and inspect every surface
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| Nonsurgical treatment: oral medications—glucosamine (helpful; few side effects); nonsteroidal anti-inflammatory
drugs (NSAIDs; ibuprofen safe in elderly); injections—hyaluronic acid helpful; steroid injections limited to
subacute isolated incident; unloader brace—good for malalignment; poor compliance in women and obese patients
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| Surgical treatment: osteotomy for malalignment—indicated for severe deformity; meniscectomy—
transplantation
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| Mechanical debridement: chondroplasty and shaver; gold standard for chondromalacia; 4.5-mm curved shaver preferred
by speaker; results—few publications; results unimpressive; fibrillation persists; removal of cartilage leads to damage
of remaining cartilage; in cases of traumatic chondromalacia patella, 57% to 73% of results good or excellent at 5
yr; in cases of unknown etiology, <50% of results good or excellent at 3 yr; in idiopathic chondromalacia patella, 29%
to 41% of results good or excellent at 5 yr
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| Thermal chondroplasty: basic science controversial but promising; few published clinical results; radiofrequency (RFE)
energy heats cartilage, not probe; other options—laser (no longer used; led to osteonecrosis); electrocautery plus
shaver (worse than shaver alone); RFE results—compared to shaver, produced more improvement at 12 and 24 mo;
complications (with ≤10,000 cases/mo, few reported)
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| MICROFRACTURE TECHNIQUE, RESULTS, AND REHABILITATION —Nicholas A. DiNubile, MD, Clinical
Assistant Professor, Department of Orthopaedic Surgery, University of Pennsylvania School of Medicine, Philadelphia
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| Chondral defects: common; not always symptomatic; natural history not well understood; healing capacity limited;
more common as population ages
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| Effect of aging on articular cartilage: healing limited; decline in cell function, synthesis, and repair; mechanical
properties weaken; osteoarthritis increases; effects not uniform; not always symptomatic
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| Incidence: ≈900,000 in United States annually, resulting in 200,000 surgeries; 61% to 63% had chondral defects; in
patients <40 yr of age undergoing arthroscopy, 11% to 40% have unadressed treatable injuries; almost always
present in patients from “baby boomer” generation
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| Indications for microfracture: focal well-contained lesion (grade III or preferably grade IV defect [1-4 cm2 ]);
varus or valgus malalignment not ≥5°; less effective with increasing age (older than ≈45 yr of age); not overweight;
compliant patient (rehabilitation key); reliable contralateral leg; otherwise—approach degenerative joint disease
(DJD) lesions conservatively; fortunately, failure to adhere to rehabilitation program does not leave patient worse
than before surgery
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| Surgical technique: extend chondroplasty to stable rim; remove calcified cartilage layer; use microfracture awls;
maintain plate integrity (leave space between holes); monitor bleeding (unless using tourniquet); use caution with
DJD lesions
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| Rehabilitation goals: cell regeneration and remodeling; stem cells creating extracellular matrix; durable repair tissue
(lengthy process, ≈2 yr); optimal environment for “newborn” cells; protocol depends on lesion size and location,
and cartilage maturation stages
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| Cartilage maturation stages: stage I—proliferation (0-6 wk); stage II—transition (7 wk to 6 mo); stage III —
remodeling (6 mo to 3 yr)
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| Protocol: immediate continuous passive motion (CPM; 1 cycle/min; 6-8 hr/day); full motion as soon as possible;
non- to minimal weight-bearing for 6 wk; bicycle; light water exercises; avoid higher impact loading and weight
training for ≈6 to 8 wk; patella different—allow full weight-bearing with knee brace or hinged brace locked 20°
to 60° for 6 to 8 wk; up and down stairs, 1-legged; avoid compression arc seen at time of surgery
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| Other measures: glucosamine plus chondroitin supplements; “skateboard slide”—“poor man’s CPM”; skateboards
available for ≈$5; use leg to slide back and forth; patients keep under desk
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| Results: much of data from Steadman; average follow-up, 11.3 yr; average age, 30 yr; isolated defects (normal ligaments
and menisci); 80% improved; results better in younger patients and larger lesions; other results—48 patients
with ≥2-yr follow-up; careful patient selection; good-to-excellent, 67%; fair, 25%; poor, 8%; better outcomes
correlated with shorter duration of symptoms, lower BMI, and defect-fill on MRI
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| Bottom line: microfracture safe, effective, easy, and minimally invasive; patient selection key; allow ≥6 mo before
return to sports; outcome “does not burn bridges”
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| AUTOLOGOUS CHONDROCYTE IMPLANTATION (ACI): PRESENT AND FUTURE APPROACHES —Dr.
DiNubile
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| Indications: patient selection key; focal isolated lesion; grade IV defect; size 2 to 12 cm2 ; stable knee (intact meniscus);
patient ≤40 yr of age for best results; compliance with rehabilitation essential; failed previous regeneration procedure
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| Insurance: companies may not cover or may underpay; obtaining approval difficult
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| Technique: involves 2 surgeries; arthroscopy to evaluate lesion and obtain cells; excision of defect and application
of patch
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| Harvest: arthroscopic; go up medial side of trochlea; use gouge to extract 2 or 3 “tic tacs” of articular cartilage,
with thin sliver of bone attached; send for harvesting; will receive l2 million chondrocytes for $12,000
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| Excise defect: open procedure; dislocation of patella may be required to sew periosteal patch to posterior side of
defect; excise defect circumferentially; measure defect (oversizing 2-3 mm) to template patch; mark noncambium
layer; apply multiple 6-0 Vicryl sutures around patch, creating water-tight seal; ensure edges flush; apply
fibrin glue around edges, leaving small opening; implant chondrocytes via injection
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| Rehabilitation: slow process; limited weight-bearing at 4 to 6 wk; early protected range of motion exercises; CPM;
skateboard slide possible; unloader brace, depending on malalignment; patellofemoral protocol different (similar to
microfracture)
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| Results: based on >1 decade in United States and 2 decades in Sweden; has undergone MRI, arthroscopic, and clinical
evaluation; results good-to-excellent (femoral condyle, 79%-89%; patellofemoral, 80%-85%); comparable to other
cartilage restoration techniques; more type II collagen tissue
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| Downside: “big procedure” (not minimally invasive); complications (patch hypertrophy; adhesions; patch delamination
[rarely]; ≤10% re-arthroscopy rate)
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| Future: matrix-induced ACI (MACI); scaffolds; tissue engineering; gene therapy; bone morphogenic proteins; extended
indications
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| End goal: predictable durable tissue (type II collagen; biomechanically sound); smaller incisions; accelerated rehabilitation
and recovery; treatment of arthritis
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| NEW CARTILAGE SCAFFOLDS —Dr. Sgaglione
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| Approach to scaffold design: based on combining predicate copolymer devices already on market with bone
graft substitute (tricalcium phosphate or calcium sulfate); stable biomaterial; osteoconductive (relating to bone anchor);
load-sharing until resorption and ingrowth (fibrous; potentially cloning of type-II collagen in areas without
chondrocytes); cost-effective and practical
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| MACI device: types I and II collagen porcine membrane (3-dimensional construct) for implantation of chondrocytes;
constitutes volume-stable scaffold; implantation press-fit or with anchor; Food and Drug Administration
(FDA) approval not expected for 10 yr; alternatives—more advanced designs developed in Italy
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| Speaker’s experience: in 2003 began implanting OsteoBiologics predicate scaffold device; polymer-rich 2.5-mm cap
on 15.5-mm calcium sulfate base (contains polymer fiber with compressive stiffness similar to adjacent bone); “user-
friendly can contour perfectly”; applicable to macrofractures; prospective study—demonstrated “compelling” tissue-
fill overlying defect; strict inclusion criteria; microfracture protocol postoperatively; treated smaller lesions; safe; “numbers
are good”; subsequent developments—OsteoBiologics acquired by Smith & Nephew in 2006; filed for FDA approval
for chondral resurfacing; device currently “on regulatory hold”
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| Final comment: scaffold devices provide practical way to restore bony defects and attempt surface congruence in
relatively easy way
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Suggested Reading
Angel MJ et al: Clinical applications of bioactive factors in sports medicine: current concepts and future trends.
Sports Med Arthrosc 14:138, 2006; Browne JE et al: Clinical outcome of autologous chondrocyte implantation at 5
years in US subjects. Clin Orthop Relat Res Jul:237, 2005; Fu FH et al: Autologous chondrocyte implantation versus
debridement for treatment of full-thickness chondral defects of the knee: an observational cohort study with 3-year
follow-up. Am J Sports Med 33:1658, 2005; Fu FH: Rate of improvement was not different after osteochondral repair
with matrix-induced autologous chondrocyte implantation or autologous chondrocyte implantation with a cover made
from porcine-derived type I/type III collagen. J Bone Joint Surg Am 87:2593, 2005; Gobbi A et al: Osteochondral
lesions of the talus: randomized controlled trial comparing chondroplasty, microfracture, and osteochondral autograft
transplantation. Arthroscopy 22:1085, 2006; Gross AE et al: Long-term followup of the use of fresh osteochondral
allografts for posttraumatic knee defects. Clin Orthop Relat Res Jun:79, 2005; Hangody L et al: Autologous osteochondral
mosaicplasty. Surgical technique. J Bone Joint Surg Am 86-A Suppl 1:65, 2004; Knutsen G et al: Autologous
chondrocyte implantation compared with microfracture in the knee. A randomized trial. J Bone Joint Surg Am
86-A:455, 2004; Kocher MS et al: Management of osteochondritis dissecans of the knee: current concepts review.
Am J Sports Med 34:1181, 2006; Malinin T et al: Transplantation of osteochondral allografts after cold storage. J
Bone Joint Surg Am 88:762, 2006; Mandelbaum B et al: Treatment outcomes of autologous chondrocyte implantation
for full-thickness articular cartilage defects of the trochlea. Am J Sports Med 35:915, 2007; Sgaglione NA et al:
Update on advanced surgical techniques in the treatment of traumatic focal articular cartilage lesions in the knee. Arthroscopy
18:9, 2002; Sgaglione NA: Biologic approaches to articular cartilage surgery: future trends. Orthop Clin
North Am 36:485, 2005; Steadman JR et al: Microfracture to treat full-thickness chondral defects: surgical technique,
rehabilitation, and outcomes. J Knee Surg 15:170, 2002; Steadman JR et al: Outcomes of microfracture for
traumatic chondral defects of the knee: average 11-year follow-up. Arthroscopy 19:477, 2003.
Educational Objectives
| The goal of this program is to improve surgical management of articular cartilage defects. After hearing and assimilating
this program, the clinician will be better able to:
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| 1. Describe the current approach to articular cartilage defects in orthopaedic practice.
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| 2. Manage partial thickness articular cartilage defects.
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| 3. Implement microfracture in treating articular cartilage defects.
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| 4. Perform autologous chondrocyte implantation.
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| 5. Explain the potential benefits of cartilage scaffolds in the restoration of bony defects and obtaining surface
congruence.
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Faculty Disclosure
In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty members to disclose
relevant financial relationships within the past 12 months that might create any personal conflicts of interest. Any
identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary
business or commercial interest. For this program, the following has been disclosed: Dr. Sgaglione—Smith
& Nephew (endoscopy); Dr. Lubowitz—Smith & Nephew (consultant; research funding); Arthrex (royalties; research
funding); Breg (research funding); Dr. DiNubile— Genzyme (consultant)
Acknowledgements
Drs. Sgaglione, Lubowitz, and DiNubile were recorded at Evaluation and Treatment of the Injured Athlete: Sports
Medicine Update 2007, sponsored by the Boston University School of Medicine in Martha’s Vineyard, MA, July 30
to August 3, 2007. The Audio-Digest Foundation thanks the speakers and the sponsor for their cooperation in the production
of this program.
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