Scott T. Ball

Prolonged Storage Effects on the Articular Cartilage of Fresh Human Osteochondral Allografts

BACKGROUND Fresh osteochondral allograft transplantation is a well-established technique for the treatment of cartilage defects of the knee. It is believed that the basic paradigm of the technique is that the transplantation of viable chondrocytes maintains the articular cartilage matrix over time. Allograft tissue is typically transplanted up to forty-two days after the death of the donor, but it is unknown how the conditions and duration of storage affect the properties of fresh human osteochondral allografts. This study examined the quality of human allograft cartilage as a function of storage for a duration of one, seven, fourteen, and twenty-eight days. We hypothesized that chondrocyte viability, chondrocyte metabolic activity, and the biochemical and biomechanical properties of articular cartilage would remain unchanged after storage for twenty-eight days. METHODS Sixty osteochondral plugs were harvested from ten fresh human femoral condyles within forty-eight hours after the death of the donor and were stored in culture medium at 4 degrees C. At one, seven, fourteen, and twenty-eight days after harvest, the osteochondral plugs were analyzed for (1) viability and viable cell density by confocal microscopy, (2) proteoglycan synthesis by quantification of (35)SO(4) incorporation, (3) glycosaminoglycan content, (4) indentation stiffness, (5) compressive modulus and hydraulic permeability by static and dynamic compression testing, and (6) tensile modulus by equilibrium tensile testing. RESULTS Chondrocyte viability and viable cell density remained unchanged after storage for seven and fourteen days (p > 0.7) and then declined at twenty-eight days (p < 0.001). Proteoglycan synthesis remained unchanged at seven days (p > 0.1) and then declined at fourteen days (p < 0.01) and twenty-eight days (p < 0.001). No significant differences were detected in glycosaminoglycan content (p > 0.8), indentation stiffness (p > 0.4), compressive modulus (p > 0.05), permeability (p > 0.3), or equilibrium tensile modulus after storage for twenty-eight days (p > 0.9). CONCLUSIONS These data demonstrate that fresh human osteochondral allograft tissue stored for more than fourteen days undergoes significant decreases in chondrocyte viability, viable cell density, and metabolic activity, with preservation of glycosaminoglycan content and biomechanical properties. The cartilage matrix is preserved during storage for twenty-eight days, but the chondrocytes necessary to maintain the matrix after transplantation decreased over that time-period.

Early results of conversion of a failed femoral component in hip resurfacing arthroplasty.

BACKGROUND A theoretical advantage of resurfacing arthroplasty of the hip is that a failed femoral component can be safely and successfully revised to a total hip arthroplasty. To our knowledge, this advantage has not been demonstrated to date. METHODS Twenty-one metal-on-metal resurfacing arthroplasties in twenty patients with an average age of 50.2 years were converted to a conventional stemmed total hip arthroplasty because of femoral component failure. In eighteen hips, the acetabular component was retained, and in three hips both components were revised. The results in the resurfacing conversion group were compared with those in a group of fifty-eight patients who had undergone sixty-four primary total hip arthroplasties that had been performed during the same time-period by the same surgeon. Clinical evaluations (the Harris hip score, the University of California at Los Angeles pain, walking, and activity scores and the Short Form-12 score) and radiographic evaluations were performed. The average duration of follow-up was forty-six months for the conversion arthroplasty group and fifty-seven months for the primary conventional total hip arthroplasty group. RESULTS There was no significant difference between the conversion arthroplasty group and the conventional arthroplasty group with regard to operative time, blood loss, or complication rates. At the time of the most recent follow-up, with the numbers studied, there were no significant differences between the two groups with regard to the mean Harris hip score; the University of California at Los Angeles pain, walking, and activity score; or the SF-12 score. As assessed radiographically, the quality of component fixation and the alignment of the reconstruction were equivalent between the two groups. There had been no instances of aseptic loosening of the femoral or the acetabular component in either group, and there had been no dislocations after conversion of a resurfacing arthroplasty. CONCLUSIONS Conversion of a hip resurfacing with a femoral-side failure to a total hip arthroplasty appears to be comparable with primary total hip arthroplasty in terms of surgical effort, safety, and early clinical outcomes. LEVEL OF EVIDENCE Therapeutic Level III. See Instructions to Authors for a complete description of levels of evidence.

The effects of storage on fresh human osteochondral allografts.

Historically, fresh human osteochondral allografts have been stored in lactated Ringer’s solution at 4° C and then transplanted as quickly as possible, generally within 2 to 5 days, to ensure delivery of a high level of viable chondrocytes. Recently, allograft distribution companies have begun to provide fresh osteochondral allografts that are stored in a proprietary culture medium usually for at least 2 weeks before delivery to the surgeon for implantation. The effects of such storage on human cartilage have not been well-defined. In the current study the effects of storage in lactated Ringer’s solution and in culture media were assessed. After 7 days of storage in lactated Ringer’s solution, a significant decline in chondrocyte viability and metabolic activity was seen. Culture media provided significantly better preservation of the cartilage with viability and metabolic activity remaining essentially unchanged from baseline for as many as 14 days. The biochemical and biomechanical properties of the extracellular matrix remained stable with storage in both solutions with time. These data suggest that osteochondral allografts stored under traditional conditions in lactated Ringer’s solution should continue to be implanted as quickly as possible and certainly within 7 days of donor death. If kept in culture media, the storage duration may be extended to approximately 2 weeks.

Follow-up of Osteochondral Plug Transfers in a Goat Model A 6-Month Study

Background Osteochondral transfer procedures are increasingly used to resurface full-thickness articular cartilage defects. There has not been long-term assessment/description of autogenous donor and recipient sites. Hypothesis The healing process occurs at the donor/host cartilage and bone interfaces. Study Design Histologic, biochemical, and biomechanical changes were assessed 6 months after an osteochondral transfer in a goat model. Methods Eight adult goats were studied. In the 6 osteochondral transfer goats, 2 autogenous plugs were transferred from the femoral trochlea to defects in the weightbearing portion of the medial femoral condyle. The goats were allowed free range for 6 months. Randomly assigned plugs were assessed. Results Knees of the sacrificed animals had preservation of the joint space with mild chondromalacic changes in both transfer and contralateral control groups. Histologically, no evidence of cartilage (host/donor) healing was seen. Subchondral bone of the plug was contiguous with the surrounding recipient bone. Cellular viability in the autogenous osteochondral plug was seen, and 35SO4 uptake of the articular cartilage was not statistically different from the contralateral control condyle. The indentation stiffness of the transfer plug (mosaicplasty) and the contralateral donor site were similar—much stiffer than normal cartilage including surrounding condylar cartilage. Large structural stiffness of transferred cores and donor sites appeared to be related to their thinner cartilage layer. Conclusions At 6-month follow-up, a cleft between host and transferred articular regions remained, with no integration between the two. Clinical Relevance Autogenous transplantation of osteochondral plugs is possible with integration of subchondral bone and preservation of chondral viability.

A Multicenter, Randomized, Triple-Masked, Placebo-Controlled Trial of The Effect of Ambulatory Continuous Femoral Nerve Blocks on Discharge-Readiness Following Total Knee Arthroplasty In Patients on General Orthopaedic Wards

&NA; A continuous femoral nerve block (cFNB) involves the percutaneous insertion of a catheter adjacent to the femoral nerve, followed by a local anesthetic infusion, improving analgesia following total knee arthroplasty (TKA). Portable infusion pumps allow infusion continuation following hospital discharge, raising the possibility of decreasing hospitalization duration. We therefore used a multicenter, randomized, triple‐masked, placebo‐controlled study design to test the primary hypothesis that a 4‐day ambulatory cFNB decreases the time until each of three predefined readiness‐for‐discharge criteria (adequate analgesia, independence from intravenous opioids, and ambulation ≥30 m) are met following TKA compared with an overnight inpatient‐only cFNB. Preoperatively, all patients received a cFNB with perineural ropivacaine 0.2% from surgery until the following morning, at which time they were randomized to either continue perineural ropivacaine (n = 39) or switch to normal saline (n = 38). Patients were discharged with their cFNB and portable infusion pump as early as postoperative day 3. Patients who were given 4 days of perineural ropivacaine attained all three criteria in a median (25th–75th percentiles) of 47 (29–69) h, compared with 62 (45–79) h for those of the control group (Estimated ratio = 0.80, 95% confidence interval: 0.66–1.00; p = 0.028). Compared with controls, patients randomized to ropivacaine met the discharge criterion for analgesia in 20 (0–38) versus 38 (15–64) h (p = 0.009), and intravenous opioid independence in 21 (0–37) versus 33 (11–50) h (p = 0.061). We conclude that a 4‐day ambulatory cFNB decreases the time to reach three important discharge criteria by an estimated 20% following TKA compared with an overnight cFNB, primarily by improving analgesia.

Ambulatory Continuous Posterior Lumbar Plexus Nerve Blocks after Hip Arthroplasty : A Dual-center, Randomized, Triple-masked, Placebo-controlled Trial

Background:The authors tested the hypotheses that after hip arthroplasty, ambulation distance is increased and the time required to reach three specific readiness-for-discharge criteria is shorter with a 4-day ambulatory continuous lumbar plexus block (cLPB) than with an overnight cLPB. Methods:A cLPB consisting of 0.2% ropivacaine was provided from surgery until the following morning. Patients were then randomly assigned either to continue ropivacaine or to be switched to normal saline. Primary endpoints included (1) time to attain three discharge criteria (adequate analgesia, independence from intravenous analgesics, and ambulation ≥ 30 m) and (2) ambulatory distance in 6 min the afternoon after surgery. Patients were discharged with their cLPB and a portable infusion pump, and catheters were removed on the fourth postoperative day. Results:Patients given 4 days of perineural ropivacaine (n = 24) attained all three discharge criteria in a median (25th–75th percentiles) of 29 (24–45) h, compared with 51 (42–73) h for those of the control group (n = 23; estimated ratio = 0.62; 95% confidence interval, 0.45–0.92; P = 0.011). Patients assigned to receive ropivacaine ambulated a median of 34 (9–55) m the afternoon after surgery, compared with 20 (6–46) m for those receiving normal saline (estimated ratio = 1.3; 95% confidence interval, 0.6–3.0; P = 0.42). Three falls occurred in subjects receiving ropivacaine (13%), versus none in subjects receiving normal saline. Conclusions:Compared with an overnight cLPB, a 4-day ambulatory cLPB decreases the time to reach three predefined discharge criteria by an estimated 38% after hip arthroplasty. However, the extended infusion did not increase ambulation distance to a statistically significant degree.

A morphologic, biochemical, and biomechanical assessment of short-term effects of osteochondral autograft plug transfer in an animal model.

PURPOSE The objective of this study was to assess the short-term changes that occur after an osteochondral autograft plug transfer from the femoral trochlea to the medial femoral condyle in a goat model. TYPE OF STUDY Articular cartilage repair animal study. METHODS Six adult male goats were used in this study. Two 4.5-mm osteochondral plugs were transferred from the superolateral femoral trochlea to 2 recipient sites in the central portion of the medial femoral condyle for a survival period of 12 weeks. Postmortem, the global effects of the procedure were assessed by gross morphologic inspection and by analyzing the synovial DNA for inflammatory response. The recipient sites were also evaluated histologically and biomechanically. Metabolic activity was determined by (35)SO(4) uptake, and viability was assessed using a live/dead stain and by confocal laser microscopy. RESULTS There was no evidence of significant gross morphologic or histologic changes in the operative knee as a result of the osteochondral donor or recipient sites. The patella, tibial plateau, and medial meniscus did not show any increased degenerative changes as a result of articulating against the donor or recipient sites of the osteochondral autografts. Analysis of synovial DNA revealed no inflammatory response. Biomechanically, 6- to 7-fold greater stiffness was noted in the cartilage of the transferred plugs compared with the control medial femoral condyle. Furthermore, on histologic examination, the healing subchondral bone interface at the recipient site had increased density. Glycosaminoglycan synthesis as determined by (35)SO(4) uptake was upregulated in the transplanted cartilage plug relative to the contralateral control, showing a repair response at the site of implantation. And finally, confocal microscopy showed 95% viability of the transferred plugs in the medial femoral condyle region. CONCLUSIONS Our findings demonstrate the ability to successfully transfer an osteochondral autograft plug with maintenance of chondrocyte cellular viability. The transferred cartilage is stiffer than the control medial femoral condyle cartilage, and there is concern regarding the increased trabecular mass in the healing subchondral plate, but these do not result in increased degenerative changes of the opposing articular surfaces in the short term.

Analysis of Cartilage Tissue on a Cellular Level in Fresh Osteochondral Allograft Retrievals

Background Fresh human osteochondral allografting is a biological cartilage replacement technique used to treat articular and osteoarticular defects in the knee. A small number of grafts fail, and we analyzed every retrieved graft during a 4-year period in order to learn more about the potential causes of failure. Hypothesis A large percentage of chondrocytes still remain viable many years after fresh osteochondral allografting. Study Design Descriptive laboratory study. Methods Retrieval specimens were obtained at the time of revision surgery and immediately analyzed. Chondrocyte viability and viable cell density were determined using a live/dead staining technique followed by confocal microscopy. Glycosaminoglycan content was a measure of the cartilage matrix. Radiolabeled sulfate uptake served as a biochemical marker of chondrocyte metabolic activity. Cartilage and subchondral bone were examined histologically. Results Fourteen patients yielded a total of 26 retrieval specimens that had been originally implanted as individual fresh osteochondral allografts. Average graft survival was 42 months. Chondrocyte viability was 82% ± 17%, and chondrocyte viable cell density was 15 590 ± 5900 viable cells/mm3. Retrieved tissue demonstrated radiolabeled sulfate uptake of 437 ± 270 counts per minute and 3.5% ± 0.8% hexosamine per dry weight. Histologically, all specimens showed some degree of cartilage fibrillation. There was evidence of bone allograft incorporation in most specimens, as well as pannus formation in 4 specimens, but no evidence of immune rejection. Conclusion A small percentage of fresh osteochondral allografts fail, but the precise cause is unknown. The main theories for failure investigated here include immunologic rejection, failure of bony incorporation, and chondrocyte death causing breakdown of the cartilage matrix. We show that chondrocytes remain viable many years after transplantation, allograft bone incorporates, and immune rejection does not seem to play a primary role in failure. Clinical Relevance Fresh osteochondral allografting is becoming more common in the treatment of articular cartilage defects in the knee. Our findings support the paradigm of fresh osteochondral allografting, the transplantation of hyaline cartilage with biological incorporation of the underlying bone scaffold. The reasons for failure of a small percentage of grafts remain unclear.

Surgical options for salvage of end-stage hallux rigidus

When approaching patients with a painful first MTP joint that has failed conservative therapy and first-line surgical treatments (cheilectomy or minor bunion procedures), the surgeon should stratify these patients based upon diagnosis, age, and activity level (Fig. 13). For the young, active patient, an arthrodesis is the gold standard, and the primary predictors of clinical and radiographic success are proper fusion angle alignment and maintenance or restoration of length. The method of fusion site preparation and the choice of fixation have not been found to be significant factors in achieving union, but based on the biomechanical data, we prefer the cup-and-cone method. Young, active patients with hallux rigidus also may be considered candidates for the investigational biologic interpositional arthroplasty procedures. Minimizing the bony resection and interposing soft tissue into the first MTP joint may provide symptomatic relief and maintain or restore motion and strength. Most importantly, this procedure does not seem to burn any bridges. If it fails, these patients can then be revised to an arthrodesis. In the elderly, inactive patient, arthrodesis is a safe and reliable treatment option. The Keller arthroplasty may be preferable, however, because it provides [figure: see text] excellent early symptomatic relief and has a less debilitating postoperative rehabilitation program. After Keller arthroplasty, patients may begin protected weight bearing immediately and after wound healing, may be advanced to weight bearing as tolerated. Whereas after fusion, most authors agree that patients should be nonweight bearing for 4-6 weeks or until there is some evidence of early radiographic union. In an older patient with inadequate upper extremity strength to manage crutches or a front-wheel walker, a first MTP fusion may result in prolonged confinement to a wheelchair. If the patient elects to undergo the Keller procedure, these patients should be counseled preoperatively about the potential complications of transfer metatarsalgia, cock-up deformity of the hallux, and weakness in the push-off phase of gait. The patients between these two extremes fall into a treatment gray zone. The arthrodesis should again be considered the gold standard because it is reliable and durable with time and activity. However, biologic or prosthetic interpositional arthroplasty are exciting investigational treatment options for these patients. If a prosthetic implant is to be used, the double-stemmed, hinged silastic implant with protective titanium grommets, or a metallic hemi-arthroplasty prosthesis, appear to be the two best choices of implant. With the continuous advances in material engineering and tissue engineering, prosthetic and biologic interpositional arthroplasties hold the greatest promise for the painful first MTP joint in the future. These treatment modalities allow restoration of alignment and maintenance of motion, length, and strength, which are fundamental in attaining a good clinical result. When the optimal material is developed (whether it is prosthetic, biologic, or a combination of both), these treatment advantages will be realized without the attendant complications associated with the use of our current implants.

Continuous peripheral nerve blocks: is local anesthetic dose the only factor, or do concentration and volume influence infusion effects as well?

Background:The main determinant of continuous peripheral nerve block effects—local anesthetic concentration and volume or simply total drug dose—remains unknown. Methods:We compared two different concentrations and basal rates of ropivacaine—but at equivalent total doses—for continuous posterior lumbar plexus blocks after hip arthroplasty. Preoperatively, a psoas compartment perineural catheter was inserted. Postoperatively, patients were randomly assigned to receive perineural ropivacaine of either 0.1% (basal 12 ml/h, bolus 4 ml) or 0.4% (basal 3 ml/h, bolus 1 ml) for at least 48 h. Therefore, both groups received 12 mg of ropivacaine each hour with a possible addition of 4 mg every 30 min via a patient-controlled bolus dose. The primary endpoint was the difference in maximum voluntary isometric contraction (MVIC) of the ipsilateral quadriceps the morning after surgery, compared with the preoperative MVIC, expressed as a percentage of the preoperative MVIC. Secondary endpoints included hip adductor and hip flexor MVIC, sensory levels in the femoral nerve distribution, hip range-of-motion, ambulatory ability, pain scores, and ropivacaine consumption. Results:Quadriceps MVIC for patients receiving 0.1% ropivacaine (n = 26) declined by a mean (SE) of 64.1% (6.4) versus 68.0% (5.4) for patients receiving 0.4% ropivacaine (n = 24) between the preoperative period and the day after surgery (95% CI for group difference: −8.0–14.4%; P = 0.70). Similarly, the groups were found to be equivalent with respect to secondary endpoints. Conclusions:For continuous posterior lumbar plexus blocks, local anesthetic concentration and volume do not influence nerve block characteristics, suggesting that local anesthetic dose (mass) is the primary determinant of perineural infusion effects.