Glenohumeral Osteoarthritis: The Role for Orthobiologic Therapies: Platelet-Rich Plasma and Cell Therapies

Autologous Peripheral Blood-Derived Orthobiologics for the Management of Shoulder Disorders: A Review of Current Clinical Evidence

INTRODUCTION

A multidisciplinary approach is recommended to manage shoulder pain, the third most common musculoskeletal disorder, but traditional modalities have limitations, providing only temporary symptomatic pain relief instead of targeting the underlying pathophysiology. Recently, autologous peripheral blood-derived orthobiologics (APBOs) have become popular for the management of shoulder disorders. Platelet-rich plasma (PRP) is the most frequently used APBO, but its efficacy remains disputable. Thus, the possibility of using other APBOs, such as platelet lysate (PL), autologous conditioned serum (ACS), gold-induced cytokine (GOLDIC), plasma rich in growth factors (PRGF), growth factor concentrate (GFC), autologous protein solution (APS), and hyperacute serum (HS), for the management of shoulder disorders have been considered. This review summarizes the outcomes of clinical studies involving APBOs to manage shoulder disorders.

METHODS

Multiple databases (PubMed, Web of Science, Embase, and Scopus) were searched employing terms for APBOs and various shoulder disorders for articles published in the English language to September 11, 2024, adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

RESULTS

Only six clinical studies fulfilled our pre-defined search and inclusion criteria. Specifically, one, two, two, and one studies involving the use of PL, ACS, PRGF, and APS, respectively, were included in this review. No clinical studies were identified involving the use of GOLDIC, GFC, and HS.

CONCLUSIONS

Administration of PL, ACS, PRGF, and APS is safe and can reduce pain and improve function in patients with shoulder disorders, including rotator cuff tendinopathy, subacromial impingement syndrome, glenohumeral osteoarthritis and delayed union fracture of the clavicle. Given the dearth of relevant literature and limitations of the available studies, more prospective clinical studies, and ideally, randomized controlled trials, with extended follow-up are necessary to establish the efficacy of APBOs and to select the ideal APBO for the management of shoulder disorders.

The degenerated glenohumeral joint

Aims

This study aimed to define the histopathology of degenerated humeral head cartilage and synovial inflammation of the glenohumeral joint in patients with omarthrosis (OmA) and cuff tear arthropathy (CTA). Additionally, the potential of immunohistochemical tissue biomarkers in reflecting the degeneration status of humeral head cartilage was evaluated.

Methods

Specimens of the humeral head and synovial tissue from 12 patients with OmA, seven patients with CTA, and four body donors were processed histologically for examination using different histopathological scores. Osteochondral sections were immunohistochemically stained for collagen type I, collagen type II, collagen neoepitope C1,2C, collagen type X, and osteocalcin, prior to semiquantitative analysis. Matrix metalloproteinase (MMP)-1, MMP-3, and MMP-13 levels were analyzed in synovial fluid using enzyme-linked immunosorbent assay (ELISA).

Results

Cartilage degeneration of the humeral head was associated with the histological presentation of: 1) pannus overgrowing the cartilage surface; 2) pores in the subchondral bone plate; and 3) chondrocyte clusters in OmA patients. In contrast, hyperplasia of the synovial lining layer was revealed as a significant indicator of inflammatory processes predominantly in CTA. The abundancy of collagen I, collagen II, and the C1,2C neoepitope correlated significantly with the histopathological degeneration of humeral head cartilage. No evidence for differences in MMP levels between OmA and CTA patients was found.

Conclusion

This study provides a comprehensive histological characterization of humeral cartilage and synovial tissue within the glenohumeral joint, both in normal and diseased states. It highlights synovitis and pannus formation as histopathological hallmarks of OmA and CTA, indicating their roles as drivers of joint inflammation and cartilage degradation, and as targets for therapeutic strategies such as rotator cuff reconstruction and synovectomy.

Glenohumeral Osteoarthritis: A Biological Advantage or a Missed Diagnosis?

(1) Background: Osteoarthritis is a degenerative joint disease that is commonly diagnosed in the aging population. Interestingly, the lower extremity joints have a higher published incidence of osteoarthritis than the upper extremity joints. Although much is known about the disease process, it remains unclear why some joints are more affected than others. (2) Methods: A comprehensive literature review was conducted utilizing the search engines PubMed, Google Scholar, and Elsevier from 2014 to 2024, directing our search to osteoarthritis of various joints, with the focus being on glenohumeral osteoarthritis. (3) Results and Discussion: The literature review revealed a publication difference, which may be explained by the inconsistency in classification systems utilized in the diagnosis of shoulder osteoarthritis. For instance, there are six classification systems employed in the diagnosis of glenohumeral osteoarthritis, making the true incidence and, therefore, the prevalence unobtainable. Furthermore, susceptibility to osteoarthritis in various joints is complicated by factors such as joint anatomy, weight-bearing status, and prior injuries to the joint. (4) Conclusions: This review reveals the lack of understanding of shoulder osteoarthritis's true incidence and prevalence while considering the anatomy and biomechanics of the glenohumeral joint. In addition, this is the first paper to suggest a single criterion for the diagnosis of glenohumeral osteoarthritis.

Efficacy of intra-articular injections of hyaluronic acid in patients with glenohumeral joint osteoarthritis: A systematic review and meta-analysis

Symptomatic primary glenohumeral (GH) joint osteoarthritis (OA) can be challenging to treat. Hyaluronic acid (HA) has emerged as a promising treatment for the nonsurgical management of GH-OA. In this systematic review with meta-analysis, we aimed to evaluate the current evidence regarding the efficacy of intra-articular HA on pain relief in patients suffering from GH-OA. A total of 15 studies (only randomized controlled trials providing data at the end of the intervention) were included. The relevant studies were selected based on the following PICO model: P: patients with diagnosis of shoulder OA; I: HA infiltrations as therapeutic intervention administered; C: no restriction for comparators assessed; O: pain, in terms of visual analog scale (VAS) or numeric rating scale. The risk of bias among the included studies was estimated using the PEDro scale. A total of 1023 subjects were analyzed. Comparing HA injections combined with physical therapy (PT) compared to PT alone resulted in superior scores, showing an overall effect size (ES) of 4.43 (p = 0.00006). Moreover, pooled analysis of VAS pain scores demonstrated a significant improvement in the ES of the HA in comparison with corticosteroid injections (p = 0.002). On average, we reported a PEDro score of 7.2. A total of 46.7% of studies showed probable signs of a randomization bias. The findings of this systematic review and meta-analysis showed that IA injections of HA might be effective on pain relief with significant improvements compared to baseline and compared to corticosteroid injections in patients affected by GH-OA.

Incongruity of the scapulohumeral arch: an indirect sign of posterior subluxation of the humeral head in primary glenohumeral osteoarthritis

BACKGROUND

In symptomatic glenohumeral osteoarthritis, arthroplasty is the gold standard to restore a mobile and painless shoulder. The kind of arthroplasty chosen is mainly based on the evaluation of the rotator cuff and the type of glenoid. The aim of this study was to analyze the scapulohumeral arch in primary glenohumeral osteoarthritis (PGHOA) with an uninjured cuff and to determine whether posterior humeral subluxation influences the Moloney line, which corresponds to an intact scapulohumeral arch.

MATERIALS AND METHODS

Between 2017 and 2020, 58 anatomic total shoulder arthroplasties were implanted in the same center. We included all patients with complete preoperative imaging (radiographs and magnetic resonance imaging or arthro-computed tomography scans) assessing an intact rotator cuff. A total of 55 shoulders that had undergone surgery with a total anatomic shoulder prosthesis were analyzed after determination of the type of glenoid in the frontal plane according to the Favard classification on an anteroposterior radiograph and in the axial plane according to the Walch classification on computed tomography scans. The grade of osteoarthritis was evaluated according to the Samilson classification. We analyzed whether there was a rupture of the Moloney line on the frontal radiograph and assessed the acromiohumeral distance.

RESULTS

After preoperative analysis of 55 shoulders, 24 shoulders had type A glenoids and 31 had type B glenoids. Scapulohumeral arch rupture was observed in 22 shoulders, and posterior subluxation of the humeral head was found in 31 shoulders, of which 25 had type B1 glenoids and 6 had type B2 glenoids according to the Walch classification. Most glenoids were type E0 (n = 47.85%). Incongruity of the Moloney line was more frequent in shoulders with type B glenoids (20 of 31 [65%]) than those with type A glenoids (2 of 24 [8%], P < .001). No patient with a type A1 glenoid (0 of 15) had a rupture of the Moloney line, and only 2 patients with a type A2 glenoid (2 of 9) had incongruity of the scapulohumeral arch.

CONCLUSION

In PGHOA, rupture of the scapulohumeral arch seen on anteroposterior radiographs, also known as the Moloney line, may be an indirect sign of posterior humeral subluxation, corresponding to a type B glenoid per the Walch classification. Incongruity of the Moloney line may indicate a rotator cuff injury or posterior glenohumeral subluxation with an intact cuff in PGHOA.

Non-operative management of shoulder osteoarthritis: Current concepts

Glenohumeral osteoarthritis (OA) is one of the most common causes of shoulder pain. Conservative treatment options include physical therapy, pharmacological therapy, and biological therapy. Patients with glenohumeral OA present shoulder pain and decreased shoulder range of motion (ROM). Abnormal scapular motion is also seen in patients as adaptation to the restricted glenohumeral motion. Physical therapy is performed to (1) decrease pain, (2) increase shoulder ROM, and (3) protect the glenohumeral joint. To decrease pain, it should be assessed whether the pain appears at rest or during shoulder motion. Physical therapy may be effective for motion pain rather than rest pain. To increase shoulder ROM, the soft tissues responsible for the ROM loss need to be identified and targeted for intervention. To protect the glenohumeral joint, rotator cuff strengthening exercises are recommended. Administration of pharmacological agents is the major part next to physical therapy in the conservative treatment. The main aim of pharmacological treatment is the reduction of pain and diminution of inflammation in the joint. To achieve this aim, non-steroidal anti-inflammatory drugs are recommended as first-line therapy. Additionally, the supplementation of oral vitamin C and vitamin D can help to slow down cartilage degeneration. Depending on the individual comorbidities and contraindications, sufficient medication with good pain reduction is thus possible for each patient. This interrupts the chronic inflammatory state in the joint and, in turn, enables pain-free physical therapy. Biologics such as platelet-rich plasma, bone marrow aspirate concentrate, and mesenchymal stem cells have gathered increased attention. Good clinical outcomes have been reported, but we need to be aware that these options are helpful in decreasing shoulder pain but neither stopping the progression nor improving OA. Further evidence of biologics needs to be obtained to determine their effectiveness. In athletes, a combined approach of activity modification and physical therapy can be effective. Oral medications can provide patients with transient pain relief. Intra-articular corticosteroid injection, which provides longer-term effects, must be used cautiously in athletes. There is mixed evidence for the efficacy of hyaluronic acid injections. There is still limited evidence regarding the use of biologics.

Substantial Variability in Platelet-Rich Plasma Composition Is Based on Patient Age and Baseline Platelet Count

Purpose

To evaluate the effect of age, sex, body mass index (BMI), and baseline blood count on the final composition of platelet rich-plasma (PRP) and to evaluate the variability of PRP applied in the same patient at 2 different times.

Methods

Potential subjects treated with PRP between January 2019 and December 2021 were identified in an institutional registry. Patient demographics and baseline blood count were prospectively recorded in a consecutive series of patients treated with PRP for a musculoskeletal condition in our Institution. The influence of sex, BMI, age, and baseline blood count on final platelet concentrations in PRP was evaluated. Finally, intrapersonal variability was evaluated.

Results

A total of 403 PRP injections from 357 patients were analyzed from an institutional prospective registry of PRP between January 2019 and December 2021. A directly proportional variation in PRP platelet count of 3.8× was observed for each unit increase in baseline blood platelet count. For every decade increase, we observed an approximate decrease of 32,666 platelets. When the first dose of PRP platelet counts was compared with the second dose of PRP platelet counts between the same patients, significant differences were found. A mean of 890,018 platelets in the first PRP and a mean of 1,244,467 in the second PRP with a mean difference of 354,448 was found (P = .008). We did not find differences in the final concentration of platelets regarding sex, BMI, or PRP protocol.

Conclusions

Overall the final composition of PRP (platelet count) was significantly influenced by patient's age and baseline platelet count. In contrast, BMI, sex and the rest of the components of the baseline blood count did not have a significant influence on final PRP. Furthermore, in patients who received 2 doses of PRP, the final concentration of platelets varied significantly between the 2 preparations.

Level of Evidence

Level IV, prognostic case series.

The role of the anterior shoulder joint capsule in primary glenohumeral osteoarthritis

The pathogenesis of primary glenohumeral arthritis (GHOA) is mediated by a complex interaction between osseous anatomy and the surrounding soft tissues. Recently, there has been growing interest in characterizing the association between the anterior shoulder joint capsule and primary GHOA because of the potential for targeted treatment interventions. Emerging evidence has shown substantial synovitis, fibrosis, and mixed inflammatory cell infiltrate in the anterior capsule of osteoarthritic shoulders. In addition, increased thickening of the anterior shoulder joint capsule has been associated with greater posterior glenoid wear and humeral head subluxation. While these findings suggest that anterior capsular disease may play a causative role in the etiology and progression of eccentric GHOA, further studies are needed to support this association. The purpose of this article is to review the pathogenesis of primary GHOA, contextualize current hypotheses regarding the role of the anterior capsule in the disease process, and provide directions for future research.

Efficacy of Ultrasound-Guided Glenohumeral Joint Injections of Leukocyte-Poor Platelet-Rich Plasma Versus Hyaluronic Acid in the Treatment of Glenohumeral Osteoarthritis: A Randomized, Double-Blind Controlled Trial

OBJECTIVE

To compare the efficacy of ultrasound-guided hyaluronic acid (HA) versus leukocyte-poor platelet-rich plasma (LP-PRP) injection in the treatment of glenohumeral osteoarthritis.

DESIGN

Double-blind randomized controlled trial.

SETTING

Academic institution.

PATIENTS

Seventy patients with chronic glenohumeral osteoarthritis were randomly assigned to receive a single injection of HA (n = 36) or LP-PRP (n = 34).

INTERVENTIONS

Leukocyte-poor platelet-rich plasma was processed using Harvest/TerumoBCT Clear PRP kits. Ultrasound-guided injections of 6 mL HA or 6 mL LP-PRP into the glenohumeral joint were performed. Patients, the injecting physician, and outcomes assessor were blinded to treatment assignments.

MAIN OUTCOME MEASURES

Shoulder Pain and Disability Index (SPADI), American Shoulder and Elbow Surgeons (ASES) score, current/average numerical rating scale (NRS) pain scores, satisfaction, and side effects were assessed at the 5 follow-up time points over 12 months.

RESULTS

Baseline characteristics were similar between groups. There were no significant between-group differences regarding SPADI, ASES, and current/average NRS pain scores at any time point up to 12 months postinjection ( P > 0.05). However, significant improvements in SPADI, ASES, and current/average NRS pain scores were observed in both groups starting at 1 or 2 months ( P < 0.01, P < 0.01, P < 0.001, and P < 0.01, respectively). These improvements were observed regardless of osteoarthritis severity. For patients who received LP-PRP, there was no effect of platelet yield on outcomes. Side effect and satisfaction rates were similar between groups.

CONCLUSIONS

There were no differences in pain and functional outcomes after a single injection of LP-PRP versus HA. However, significant improvements in pain and function were observed after both treatments in patients with glenohumeral osteoarthritis.

The association between anterior shoulder joint capsule thickening and glenoid deformity in primary glenohumeral osteoarthritis

BACKGROUND

Anterior shoulder joint capsule thickening is typically present in osteoarthritic shoulders, but its association with specific patterns of glenoid wear is incompletely understood. We sought to determine the relationship between anterior capsular thickening and glenoid deformity in primary glenohumeral osteoarthritis.

METHODS

We retrospectively identified 134 consecutive osteoarthritic shoulders with magnetic resonance imaging and computed tomography scans performed. Axial fat-suppressed magnetic resonance imaging slices were used to quantify the anterior capsular thickness in millimeters, measured at its thickest point below the subscapularis muscle. Computed tomography scans were used to classify glenoid deformity according to the Walch classification, and an automated 3-dimensional software program provided values for glenoid retroversion and humeral head subluxation. Multinomial and linear regression models were used to characterize the association of anterior capsular thickening with Walch glenoid type, glenoid retroversion, and posterior humeral head subluxation while controlling for patient age and sex.

RESULTS

The anterior capsule was thickest in glenoid types B2 (5.5 mm, 95% confidence interval [CI]: 5.0-6.0) and B3 (6.1 mm, 95% CI: 5.6-6.6) and thinnest in A1 (3.7 mm, 95% CI: 3.3-4.2; P < .001). Adjusted for age and sex, glenoid types B2 (odds ratio: 4.4, 95% CI: 2.3-8.4, P < .001) and B3 (odds ratio: 5.4, 95% CI: 2.8-10.4, P < .001) showed the strongest association with increased anterior capsule thickness, compared to glenoid type A1. Increased capsular thickness correlated with greater glenoid retroversion (r = 0.57; P < .001) and posterior humeral head subluxation (r = 0.50; P < .001). In multivariable analysis, for every 1-mm increase in anterior capsular thickening, there was an adjusted mean increase of 3.2° (95% CI: 2.4-4.1) in glenoid retroversion and a 3.8% (95% CI: 2.7-5.0) increase in posterior humeral head subluxation.

CONCLUSIONS

Increased thickening of the anterior shoulder capsule is associated with greater posterior glenoid wear and humeral head subluxation. Additional research should determine whether anterior capsular disease plays a causative role in the etiology or progression of eccentric glenohumeral osteoarthritis.

Effectiveness of intradiscal platelet rich plasma for discogenic low back pain without Modic changes: A randomized controlled trial

Objective

To determine if autologous platelet-rich plasma (PRP) injection into a degenerative intervertebral disc, without Modic changes on magnetic resonance imaging (MRI), improve pain and function.

Design

Prospective, randomized controlled study.

Setting

Outpatient spine practice (Stichting Rugpoli, Netherlands).

Participants

Adults with chronic low back pain referred to Stichting Rugpoli, according to the Dutch General Practitioners Guidelines, unresponsive to conservative treatment, without Modic changes on MRI.

Methods

Provocation discography was performed to confirm the suspected disc was the source of pain. Participants were randomized to receive 1.0 ​cc intradiscal PRP (intervention) or 1.0 ​cc Saline with 0.2g Kefzol (control). Data on pain (Numeric Rating Scale), physical function (Roland Morris Disabilty Questionnaire, RMDQ), and participants' general perceived health (SF-12) were collected at 1 week, 4 weeks, 2 months, 6 months, 9 months and 1 year. A repeated-measures analysis (mixed model) was used for comparing the outcomes of the groups.

Results

Of the initial 98 (49 intervention, 49 control) patients randomized, 89 (91%) (44 intervention, 45 control) with complete outcome data were analyzed. Groups were balanced at baseline. After twelve months no differences between groups were found in the average pain (improved 21/44 in intervention vs 16/45 in control, p ​= ​0.244), the disability scores (RMDQ minimal 3 points improvement 22/44 in intervention vs 24/45 in control, p ​= ​0.753) and the SF-12 (mean difference physical health -1.19, 95% CI -5.39 to 2.99, p ​= ​0.721, and mental health -0.34, 95% CI -3.99 to 3.29, p ​= ​0.834). One serious adverse event occurred (spondylodiscitis) after intervention.

Conclusion

Participants who received intradiscal PRP showed no significant improvement in pain or functionality compared to the control group at 1 year follow up.

The American stem cell sell in 2021: U.S. businesses selling unlicensed and unproven stem cell interventions

In March 2021, 1,480 U.S. businesses operating 2,754 clinics were found selling purported stem cell treatments for various indications. More than four times as many businesses than were identified 5 years ago are selling stem cell products that are not FDA-approved and lack convincing evidence of safety and efficacy.

American Medical Society for Sports Medicine Position Statement: Principles for the Responsible Use of Regenerative Medicine in Sports Medicine

ABSTRACT

Many sports medicine physicians are currently considering introducing regenerative medicine into their practice. Regenerative medicine and the subclassification of orthobiologics are a complicated topic and have produced widely varying opinions. Although there is concern by government regulators, clinicians, scientists, patient advocacy organizations, and the media regarding the use of regenerative medicine products, there is also excitement about the potential benefits with growing evidence that certain regenerative medicine products are safe and potentially efficacious in treating musculoskeletal conditions. Sports medicine physicians would benefit from decision-making guidance about whether to introduce orthobiologics into their practice and how to do it responsibly. The purpose of this position statement is to provide sports medicine physicians with information regarding regenerative medicine terminology, a brief review of basic science and clinical studies within the subclassification of orthobiologics, regulatory considerations, and best practices for introducing regenerative medicine into clinical practice. This information will help sports medicine physicians make informed and responsible decisions about the role of regenerative medicine and orthobiologics in their practice.

Injection of Bone Marrow Aspirate for Glenohumeral Joint Osteoarthritis: A Pilot Randomized Control Trial

Purpose

To compare the efficacy of a single, intra-articular, nonconcentrated bone marrow aspirate (BMA) injection in comparison to cortisone for the treatment of glenohumeral joint osteoarthritis (GHJ OA).

Methods

Inclusion criteria were patients between the ages of 18 and 75 with a diagnosis of GHJ OA on radiograph. Patients were randomized to receive an ultrasound-guided, intra-articular cortisone injection or BMA injection (without concentration). The primary outcome measure was the Western Ontario Osteoarthritis of the Shoulder (WOOS) index at 12 months. Secondary outcome measures were the QuickDASH, EuroQOL 5-dimensions 5-level questionnaire (EQ-5D-5L) and visual analogue scale.

Results

The study included 25 shoulders of 22 patients who completed baseline and 12 months’ patient-reported outcome measures (12 shoulders received cortisone, 13 shoulders received BMA) after the study was terminated early by changes in Health Canada regulations. Baseline characteristics demonstrated a significant difference in the ages of the 2 groups, with the BMA group being older (61.6 vs 53.8 mean years, P = 0.021). For the BMA group, a significant improvement was seen in the WOOS index (P = 0.002), the QuickDASH (P < 0.001), and the EQ-5D-5L pain dimension (P = 0.004) between baseline and 12 months. No significant difference was seen for any outcome in the cortisone group between baseline and 12 months. No significant difference was demonstrated between changes in the WOOS scores from baseline to 12 months when compared between groups (P = 0.07). However, a significant difference in changes in scores was seen in the QuickDASH (P = 0.006) and the EQ-5D-5L pain scores (P = 0.003) and the EQ-5D-5L health scores (P = 0.032) in favor of BMA.

Conclusions

The results of this study demonstrate that patients with GHJ OA treated with BMA have superior changes in the QuickDASH and EQ-5D-5L pain and health scores but not in the WOOS outcomes measures at 12 months post injection when compared to patients treated with cortisone. However, because of the limited number of patients as a result of the early termination of the study, larger randomized studies are required to confirm these findings.

Level of Evidence

Level II, randomized controlled trial.

Nonoperative and Operative Soft-Tissue, Cartilage, and Bony Regeneration and Orthopaedic Biologics of the Shoulder: An Orthoregeneration Network (ON) Foundation Review

Orthoregeneration is defined as a solution for orthopaedic conditions that harnesses the benefits of biology to improve healing, reduce pain, improve function, and optimally, provide an environment for tissue regeneration. Options include drugs, surgical intervention, scaffolds, biologics as a product of cells, and physical and electro-magnetic stimuli. The goal of regenerative medicine is to enhance the healing of tissue after musculoskeletal injuries as both isolated treatment and adjunct to surgical management, using novel therapies to improve recovery and outcomes. Various orthopaedic biologics (orthobiologics) have been investigated for the treatment of pathology involving the shoulder including the rotator cuff tendons, glenohumeral articular cartilage, glenoid labrum, the joint capsule, and bone. Promising and established treatment modalities include hyaluronic acid (HA); platelet-rich plasma (PRP) and platelet rich concentrates (PRC); bone marrow aspirate (BMA) comprising mesenchymal stromal cells (MSCs alternatively termed medicinal signaling cells and frequently, misleadingly labelled "mesenchymal stem cells"); MSC harvested from adipose, umbilical, or placental sources; factors including vascular endothelial growth factors (VEGF), basic fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), transforming growth factor-beta (TGFβ), bone morphogenic protein (BMP), and matrix metalloproteinases (MMPs); prolotherapy; pulsed electromagnetic field therapy; microfracture and other marrow-stimulation techniques; biologic resurfacing using acellular dermal allografts, allograft Achilles tendons, allograft lateral menisci, fascia lata autografts, and porcine xenografts; osteochondral autograft or allograft); and autologous chondrocyte implantation (ACI). Studies involving hyaluronic acid, platelet rich plasma, and medicinal signaling cells of various origin tissues have shown mixed results to-date as isolated treatments and as surgical adjuncts. Despite varied results thus far, there is great potential for improved efficacy with refinement of current techniques and translation of burgeoning preclinical work. LEVEL OF EVIDENCE: Level V, expert opinion.