Jae Hyup Lee

Does Platelet-Rich Plasma Accelerate Recovery After Rotator Cuff Repair? A Prospective Cohort Study

Background: Platelet-rich plasma (PRP) has been recently used to enhance and accelerate the healing of musculoskeletal injuries and diseases, but evidence is still lacking, especially on its effects after rotator cuff repair. Hypothesis: Platelet-rich plasma accelerates recovery after arthroscopic rotator cuff repair in pain relief, functional outcome, overall satisfaction, and enhanced structural integrity of repaired tendon. Study Design: Cohort study; Level of evidence, 2. Methods: Forty-two patients with full-thickness rotator cuff tears were included. Patients were informed about the use of PRP before surgery and decided themselves whether to have PRP placed at the time of surgery. Nineteen patients underwent arthroscopic rotator cuff repair with PRP and 23 without. Platelet-rich plasma was prepared via plateletpheresis and applied in the form of a gel threaded to a suture and placed at the interface between tendon and bone. Outcomes were assessed preoperatively and at 3, 6, 12, and finally at a minimum of 16 months after surgery (at an average of 19.7 ± 1.9 months) with respect to pain, range of motion, strength, and overall satisfaction, and with respect to functional scores as determined using the following scoring systems: the American Shoulder and Elbow Surgeon (ASES) system, the Constant system, the University of California at Los Angeles (UCLA) system, the Disabilities of the Arm, Shoulder and Hand (DASH) system, the Simple Shoulder Test (SST) system, and the Shoulder Pain and Disability Index (SPADI) system. At a minimum of 9 months after surgery, repaired tendon structural integrities were assessed by magnetic resonance imaging. Results: Platelet-rich plasma gel application to arthroscopic rotator cuff repairs did not accelerate recovery with respect to pain, range of motion, strength, functional scores, or overall satisfaction as compared with conventional repair at any time point. Whereas magnetic resonance imaging demonstrated a retear rate of 26.7% in the PRP group and 41.2% in the conventional group, there was no statistical significance between the groups (P = .388). Conclusion: The results suggest that PRP application during arthroscopic rotator cuff repair did not clearly demonstrate accelerated recovery clinically or anatomically except for an improvement in internal rotation. Nevertheless, as the study may have been underpowered to detect clinically important differences in the structural integrity, additional investigations, including the optimization of PRP preparation and a larger randomized study powered for healing rate, are necessary to further determine the effect of PRP.

In vitro and in vivo evaluation of the bioactivity of hydroxyapatite-coated polyetheretherketone biocomposites created by cold spray technology.

Polyetheretherketone (PEEK) is a material that is widely used in medicine because its mechanical properties show excellent similarity to those of human bone. However, because it is bioinert, PEEK shows limited ability to bind to natural bone tissue. Here, we applied a cold spray method to make a hydroxyapatite (HA)-coated PEEK hybrid material and evaluated its osteointegration in vitro and in vivo. With the cold spray method, the HA coating formed a homogeneous layer and adhered strongly to the PEEK disk implant. When the material was tested in vitro, early cell adhesion and viability improved. Alkaline phosphatase (ALP) activity and calcium concentration were also higher in cells cultured on HA-coated PEEK disks. In addition, the expression of osteoblast differentiation markers, such as ALP, bone sialoprotein and runt-related transcription factor 2, increased in these cells. For the in vivo test, we designed and implanted HA-coated PEEK cylinders into a rabbit ilium model by the press-fit method. The bone-implant contact ratio, trabecular number and trabecular thickness were determined using either three-dimensional microcomputed tomography or general two-dimensional histomorphometric analysis. This report demonstrates that the HA coating on the PEEK implant added with the cold spray method increased biocompatibility in vitro and promoted osteointegration in vivo, which suggests that the HA coating may improve the biofunctionality of various medical devices used in clinical applications.

Subsidence and Nonunion after Anterior Cervical Interbody Fusion Using a Stand-Alone Polyetheretherketone (PEEK) Cage

Background The purposes of the present study are to evaluate the subsidence and nonunion that occurred after anterior cervical discectomy and fusion using a stand-alone intervertebral cage and to analyze the risk factors for the complications. Methods Thirty-eight patients (47 segments) who underwent anterior cervical fusion using a stand-alone polyetheretherketone (PEEK) cage and an autologous cancellous iliac bone graft from June 2003 to August 2008 were enrolled in this study. The anterior and posterior segmental heights and the distance from the anterior edge of the upper vertebra to the anterior margin of the cage were measured on the plain radiographs. Subsidence was defined as ≥ a 2 mm (minor) or 3 mm (major) decrease of the segmental height at the final follow-up compared to that measured at the immediate postoperative period. Nonunion was evaluated according to the instability being ≥ 2 mm in the interspinous distance on the flexion-extension lateral radiographs. Results The anterior and posterior segmental heights decreased from the immediate postoperative period to the final follow-up at 1.33 ± 1.46 mm and 0.81 ± 1.27 mm, respectively. Subsidence ≥ 2 mm and 3 mm were observed in 12 segments (25.5%) and 7 segments (14.9%), respectively. Among the expected risk factors for subsidence, a smaller anteroposterior (AP) diameter (14 mm vs. 12 mm) of cages (p = 0.034; odds ratio [OR], 0.017) and larger intraoperative distraction (p = 0.041; OR, 3.988) had a significantly higher risk of subsidence. Intervertebral nonunion was observed in 7 segments (7/47, 14.9%). Compared with the union group, the nonunion group had a significantly higher ratio of two-level fusion to one-level fusions (p = 0.001). Conclusions Anterior cervical fusion using a stand-alone cage with a large AP diameter while preventing anterior intraoperative over-distraction will be helpful to prevent the subsidence of cages. Two-level cervical fusion might require more careful attention for avoiding nonunion.

Fusion rates and subsidence of morselized local bone grafted in titanium cages in posterior lumbar interbody fusion using quantitative three-dimensional computed tomography scans.

Study Design. Prospective, controlled study. Objective. To determine fusion rates, cage to bone contact area ratios, and subsidences using titanium cages filled with a local bone graft for posterior lumbar interbody fusion (PLIF). Summary of Background Data. PLIF using decompressed local bone inserted in titanium cages combined with pedicle screw fixation is a popular procedure for treating lumbar spine degeneration. There is no report about cage to bone contact area ratios using titanium cages filled with a local bone graft for PLIF. Methods. PLIF using a titanium cage filled with excised laminar and facet joint bone with pedicle screw fixation was performed in 54 (78 levels) consecutive patients. Mean age at the time of surgery was 62.5 years. Radiographic assessments of posterior and anterior disc heights were performed. Three-dimensional thin-section computed tomography assessments of cage subsidences, fused area ratios of local bone inside cages, and overall fusion rates were analyzed. Results. Mean values of anterior and posterior disc heights at 1 year after surgery were significantly greater than mean preoperative disc heights. The fusion rate of cages over both upper and lower segment endplates was 96.2%. The ratios of fused areas of local bone inside cages exposed to upper and lower segment endplates were 46.7% and 52.2% in the coronal plane and 46.4% and 49.9% in the sagittal 3-dimensional computed tomography plane, respectively. And, subsidences of titanium cages at upper and lower segment endplates were 1.26 mm and 0.72 mm in the coronal plane and 1.04 mm and 0.53 mm in the sagittal plane, respectively. Conclusion. The ratio of fused area of local bone inside cages at regions exposed to endplates was <50%, which is insufficient for physiologic load transmission. The authors recommend that additional bone should be grafted into the disc space or new bone bonding interbody spacer should be considered.

Scoliosis associated with syringomyelia: analysis of MRI and curve progression

Little is known about the natural history of scoliosis found in patients with syringomyelia, including the factors affecting scoliosis curve progression and the effect of syrinx drainage treatment. Twenty patients having scoliosis with syringomyelia diagnosed by MRI were followed up for 6.6 (range 2.0–12.6) years on an average. Various factors potentially influencing curve pattern or progression in these patients were then retrospectively reviewed. The convex side of major curve of scoliosis tended to be on the same side as the syrinx and as the unilateral neurologic abnormality. No correlation was found between the location and the size of the syrinx and the location and size of the major curve of the scoliosis, or between the severity of neurologic deficit and the size of the major curve of the scoliosis. In patients under the age of ten at the time of diagnosis of scoliosis and with a flexible curve, decompression of the syrinx improved or stabilized scoliosis. In most patients over the age of ten, surgical treatment of the scoliosis was necessary because of the large initial size of the curve or progression of the curve even after syrinx drainage. Other factors including gender, location of the syrinx, type of the curve, and severity of neurologic deficits did not correlate with the progression of the curve. The results of this retrospective study suggest that early diagnosis and decompression of a syrinx in scoliosis patients especially under the age of ten is crucial and may decrease the curve size and limit scoliosis curve progression.

A prospective consecutive study of instrumented posterolateral lumbar fusion using synthetic hydroxyapatite (Bongros®-HA) as a bone graft extender

A prospective, single institution, clinical case-matched, radiographic study was undertaken. Thirty-two patients underwent posterior lumbar interbody fusion with cages containing laminectomized bone chips and posterolateral lumbar fusion with pedicle screws. Autogenous bone graft (3 mL) plus 3 mL of hydroxyapatite was placed in one side of a posterolateral gutter, and 6 mL of autogenous iliac bone graft was placed on the other side. Bony union, volumes of fusion mass, and bone absorption rates were postoperatively evaluated using simple radiographs and 3D-CT scans. Average postoperative Lenke scores at 3 and 6 months in the hydroxyapatite group were statistically higher than in the autograft group, but at 12 months no difference was found between the hydroxyapatite and autograft groups in terms of fusion rate. Complete fusion rates by 3D-CT were 86.7% in the hydroxyapatite group and 88.9% in the autograft group, which are not significantly different. Volumes of fusion mass and bone absorption rates at 12 months were 2.35 mL in the hydroxyapatite group and 1.31 mL in the autograft group. The mean fusion mass volume was greater in the hydroxyapatite group than in the autograft group. Lumbar posterolateral fusion using a mixture of hydroxyapatite artificial bone and autogenous bone graft showed good bony union similar to that shown with autogenous bone only. This study suggests that hydroxyapatite bone chips could be used usefully as a bone-graft extender in short-segment posterolateral spinal fusion.

Comparative study of fusion rate induced by different dosages of Escherichia coli–derived recombinant human bone morphogenetic protein-2 using hydroxyapatite carrier

BACKGROUND CONTEXT Hydroxyapatite (HA) is considered to be useful because of its high affinity for recombinant human bone morphogenetic protein (rhBMP), mechanical resistance to compressive force, and possible reduction of rhBMP dose. PURPOSE To evaluate the osteoinductivity of Escherichia coli-derived rhBMP-2 and the suitability of porous HA as an rhBMP-2 carrier. STUDY DESIGN In vivo study using microcomputerized tomography (micro-CT) scanning. PATIENT SAMPLE Seventy-six New Zealand white male rabbits were randomized into a single control group (n=14) without rhBMP-2 and four experimental groups (10 μg, 50 μg, 200 μg, and 500 μg of rhBMP-2; n=14 in each group). The subjects were divided into 3- and 6-week groups. OUTCOME MEASURES Outcome was evaluated by radiography, bending test, three-dimensional micro-CT, and histologic examinations. METHODS Bilateral posterolateral fusion was carried out, and rhBMP-2 (0, 10, 50, 200, 500, 1,000, and 2,000 μg) was implanted into the bilateral transverse processes using HA as a carrier. RESULTS The fusion rates of the 3-week group were 83.3% for 50 and 200 μg of rhBMP-2 and 100% for 500 μg. The improved fusion rates of the 50 μg or higher groups compared with those of control were statistically significant. The fusion rates of the 6-week group were 75% for 10 μg of rhBMP-2 and 100% for 50 μg or higher. Similarly, the improved fusion rates of the 10 μg or higher groups compared with those of control were statistically significant. Significantly higher percent volumes were observed in the 3-week 200 μg of rhBMP-2 group and 6-week 200 μg of rhBMP-2 group than the 3-week HA group and 6-week HA group, respectively. Trabecular thickness was significantly higher in the 3-week 200 μg of rhBMP-2 group than the 3-week HA group. Histologic analysis of the 10 μg group showed bone tissues within the pores from 3 weeks, and this was observed more vividly in the 50, 200, and 500 μg groups. The 6-week 10 μg and 50 μg of rhBMP-2 groups had lower amounts of new tissue but higher portions of complete bone tissue within the HA specimen, along with higher formation of completely reconstituted bone tissues outside HA. CONCLUSIONS Injection of 50 μg or more of E. coli-derived rhBMP-2 into a HA carrier induced earlier bone fusion in the intertransverse process of rabbits, which confirms the excellent bone forming ability of E. coli-derived rhBMP-2 and the suitability of HA as a carrier of rhBMP-2.

The First Clinical Trial of Beta-Calcium Pyrophosphate as a Novel Bone Graft Extender in Instrumented Posterolateral Lumbar Fusion

Background Porous β-calcium pyrophosphate (β-CPP) was developed to improve the fusion success of posterolateral lumbar fusion (PLF). The possibility of accomplishing PLF using a mixture of porous β-CPP and iliac bone was studied. This paper reports the radiologic results of PLF using the β-CPP plus autograft for lumbar degenerative disease as a bone graft extender. Methods A prospective, case-matched, radiographic study evaluating the results of short segment lumbar fusion using a β-CPP plus autograft was performed to compare the efficacy of β-CPP plus autograft with that of an autograft alone for short segment lumbar fusion. Thirty one consecutive patients (46 levels) underwent posterolateral fusion with pedicle screw fixation and additional posterior lumbar interbody fusion. In all patients, 3 mL of β-CPP plus 3 mL of autogenous bone graft was placed randomly in one side of a posterolateral gutter, and 6 mL of autogenous iliac bone graft was placed on the other. The fusion rates, volumes of fusion masses, and bone absorption percentage were evaluated postoperatively using simple radiographs and 3 dimensional computed tomography (3D-CT) scans. Results The control sides treated with an autograft showed significantly better Lenke scores than the study sides treated with β-CPP at 3 and 6 months postoperatively, but there was no difference between the two sides at 12 months. The fusion rates (confirmed by 3D-CT) were 87.0% in the β-CPP group and 89.1% in the autograft group, which were not significantly different. The fusion mass volumes and bone absorption percentage at 12 months postoperatively were 2.49 mL (58.4%) and 1.89 mL (69.5%) for the β-CPP and autograft groups, respectively, and mean fusion mass volume was significantly higher in the β-CPP group. Conclusions β-CPP combined with an autograft is as effective as autologous bone for grafting during instrumented posterolateral spinal fusion. These findings suggest that β-CPP bone chips can be used as a novel bone graft extender for short-segment posterolateral spinal fusion.

Porous Beta-Calcium Pyrophosphate as a Bone Graft Substitute in a Canine Bone Defect Model

Hydroxyapatite(HA) has been used in various situations in which bone aug mentation and restoration are required. Porous HA has been used either alone or in conjugation with freez e dried or autogenous bone , with variable clinical success. However, it has a de fect that it is relatively bio-inert and remains in the host body for a long time. In this study, porous -calcium pyrophosphate( -CPP) has been compared with porous HA in an canine bone defect model to discover the possibility as a bone graft substitute replacing porous HA. Porous HA and porous -CPP were implanted in the proximal tibia of 5 dogs. 2 animals were sacrificed at 8 weeks a nd 3 animals were sacrificed at 20 weeks after surgery. Radiographs were obtained every 4 weeks and histologi c sections of the implant site were obtained at the time of sacrifice. By serial radi ography, both implants showed contraction of radio-opaque area, blurring of graft margin, and piecemeal patterned i ncorporation of surrounding new bone. But these changes were more prominent in porous -CPP compared with porous HA and showed more rapid resorbing features. Porous HA and porous -CPP were completely integrated into newly formed bone after partial degradation and bony tissue ingrowth wa s progressing during the study period. In the case of porous -CPP, the new bone growth was as vigorous as in HA, but the pore is larger and the wall of the scaffold is thinner and bone ingrow th in gaps between the implants was more evident than in HA, which suggest more rapid degradation of -CPP in vivo. Preliminary report of our experiment suggests that porous -CPP appears to provide an alternative graft material that is bioactive, more completely incorporated and more rapidly resorbable than porous HA .

Surgical treatment of severe angular kyphosis with myelopathy: anterior and posterior approach with pedicle screw instrumentation.

Study Design. Retrospective study. Objective. To evaluate the outcomes of anterior decompression and fusion followed by posterior instrumented fusion using pedicle screws without intentional correction of severe angular kyphosis deformity with myelopathy. Summary of Background Data. Treatment of severe angular kyphosis with myelopathy is extremely difficult and dangerous. Although surgical circumferential spinal osteotomy via a single posterior approach has been reported in several studies, serious neurologic complications are a possible outcome. Materials and Methods. Among 51 patients surgically treated for angular kyphosis from 1988 to 2004, 16 patients (follow-up period, 32–168 months; mean, 72 months) with severe (>70°) angular kyphosis with progressive myelopathic symptoms underwent anterior decompression and fusion, followed by posterior pedicle screw instrumentation and bone graft without attempted correction of the deformity. Radiologic assessment, clinical findings including pain and daily activity scores, and neurologic status using the modified Frankel grade were analyzed before surgery and at the last follow-up. Results. Curve progression or nonunion did not occur in any of the cases. The mean pain and daily activity score were 3.1 and 2.3 before surgery and 4.7 and 4.2 after surgery, respectively. The modified Frankel grade indicated that every patient but one had improved neurologic function by one or more grades. Nine (75%) of 12 patients with ankle clonus, 10 (71%) of 14 patients with Babinski sign, and 6 (55%) of 11 patients with bowel and bladder dysfunction showed full improvement at the last follow-up. Postoperative complications included 1 screw pullout case and 2 infection cases which resolved without incidence. Conclusion. Anterior decompression and fusion followed by posterior pedicle screw instrumentation and fusion without correction effectively improved neurologic symptoms and halted progression of kyphotic deformity in cases of severe angular kyphosis with myelopathy.