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Biomedical subjects

Akio Minami

Publications and source records attributed to Akio Minami.

At least 55 records · Page 3Linked to original sources
PubMed2005

Influence of distal radioulnar joint subluxation on restricted forearm rotation after distal radius fracture.

PURPOSE: To analyze the influence of subluxation of the distal radioulnar joint (DRUJ) on restricted forearm rotation after distal radius fracture. METHODS: Twenty-two cases of healed unilateral distal radial fracture with restricted forearm rotation were included in the study. The subluxation of the DRUJ was evaluated using helical computed tomography scan at neutral, maximum pronation, and maximum supination and presented as the percent displacement of the ulnar head in both the injured and uninjured sides. The radiographic parameters of palmar tilt, radial inclination, dorsal shift, radial shift, and ulnar variance were measured on plain x-ray films and the rotational deformity of the distal radius was evaluated from the computed tomography scan. The differences of each radiographic parameter from the uninjured side were calculated. The relationships between the restricted forearm rotation and the percent displacement of the ulnar head and each of the radiographic parameters were analyzed statistically. RESULTS: When forearm pronation was restricted the ulnar head was located palmarly at neutral, maximum supination, and maximum pronation with severe dorsal tilt of the distal radius. When supination was restricted the ulnar head was located dorsally at maximum supination with severe ulnar-positive variance. CONCLUSIONS: The subluxation of the DRUJ was related to restricted forearm rotation. The radiographic parameters of palmar tilt and ulnar variance showed an adverse influence on the position of the ulnar head at the DRUJ, which might lead to restricted forearm rotation after distal radial fracture.

Adult↗
PubMed2005

Lumbar disc herniation associated with separation of the ring apophysis: is removal of the detached apophyses mandatory to achieve satisfactory results?

There are three questions to be addressed in lumbar disc herniation with separation of the ring apophysis: does this lesion occur only in adolescents, does any trauma predispose this lesion, and is removal of the detached apophyses mandatory to achieve satisfactory results? We prospectively investigated 32 consecutive patients (22 men, 10 women; mean age, 25.4 years; mean followup, 4 years 8 months). This lesion occurred not only in adolescents, but also in adults older than 30 years. Eight patients (25%) were younger than 20 years, whereas 14 patients (43.8%) were in the third decade, and 10 (31.2%) were in the fourth decade. Only five patients (15.6%) had antecedent traumatic episodes. Resection of the fragment did not influence the clinical results. Excision of the herniated disc and mobile bony fragment was done in 11 patients (34.4%). Discectomy alone was done in 21 patients (65.6%) with immobile bony fragments. Satisfactory results were obtained in both groups. Lumbar disc herniation with detachment of the ring apophysis can occur, without any relationship to trauma, in adults and adolescents. Removal of the bony fragment is not always needed to achieve satisfactory results.

Adolescent↗
PubMed2005

Intertrochanteric varus osteotomy for osteoarthritis in patients with hip dysplasia: 6 to 28 years followup.

UNLABELLED: There have been few reports regarding midterm to long-term results of intertrochanteric varus osteotomy for treatment of hip dysplasia. We investigated 55 hips in 46 patients, with an average age at surgery of 32 years (range, 12-55 years), for an average followup of 17 years (range, 6-28 years). Preoperative osteoarthritis was Tonnis Grade 0 in seven hips, Grade 1 in 23 hips, Grade 2 in 21 hips, and Grade 3 in four hips. Preoperative anteroposterior radiographs of the 55 hips showed almost perfect congruency between the acetabulum and the femoral head with the hip in an abducted position. Excellent or good clinical results were obtained in 23 hips (42%). Using a Harris hip score less than 70 points or the time until additional surgery as the end point, the cumulative rates of survival were 81% at 10 years, 60% at 20 years, and 50% at 25 years. The clinical results of patients with Grade 0, 1, or 2 osteoarthritis, with good spherical femoral head and mild dysplasia, were acceptable; however, this osteotomy might not be indicated for patients with Grade 3 osteoarthritis or for those with severe acetabular dysplasia. LEVEL OF EVIDENCE: Therapeutic study, Level IV (case series--no, or historical control group). See the Guidelines for Authors for a complete description of levels of evidence.

Adolescent↗
PubMed2005

Radial osteotomies for teenage patients with Kienböck disease.

Age seems to affect the efficacy of radial osteotomies for Kienböck disease. We questioned whether an osteotomy would produce acceptable results in teenagers. We retrospectively identified 11 patients (six males and five females) between 11-19 years of age who were treated with radial osteotomies for Kienböck disease. Preoperatively, three patients had Lichtman Stage II disease, two patients had Stage IIIA disease, and six patients had Stage IIIB disease. Two patients with zero or positive ulnar variance had lateral closing wedge osteotomies, and nine patients with negative ulnar variance had radial shortenings. All patients were evaluated clinically and radiographically. At a mean followup of 50 months, 10 of 11 patients were free from pain, and the remaining one patient had moderate wrist pain during strenuous activity. All patients except one, who had Stage IIIB disease, had an excellent clinical outcome. Radiographic improvement, indicating lunate revascularization, was seen for eight patients. Despite Stage IIIB disease, radial osteotomies produced excellent clinical results in five of six teenage patients. The current results indicate that radial osteotomies are effective in improving not only short-term clinical outcomes, but also radiographic findings in teenage patients with Kienböck disease.

Adolescent↗
PubMed2005

Limb length and girth discrepancy of unilateral congenital clubfeet.

There have been few reports about hypoplasia of the femur and tibia in congenital clubfeet. The subjects of this study were 38 patients with unilateral congenital clubfoot. All the measurements were significantly less in the affected side than in the normal side. Although the decrease in length itself was higher in the distal segment, the tibial length contributed mostly to limb length shortening. There was no significant difference between male and female patients. Only the tibial length and the calf girth were significantly less in patients who had undergone surgery than in those without. The discrepancies might not improve with growth, as there was no significant difference between bony mature patients and those who were immature. We conclude that hypoplasia of the femur and the tibia, not only the tarsal bones, does exist to some extent, or it can be said that there must be a generalized decrease in limb size in congenital clubfeet.

Adolescent↗
PubMed2005

A long-term follow-up of silicone-rubber interposition arthroplasty for osteoarthritis of the thumb carpometacarpal joint.

There are several surgical options for osteoarthritis (OA) of the thumb carpometacarpal (CMC) joint. This paper presents our long-term clinical and radiographic review of 12 thumbs in ten patients treated by partial trapezial excision and silicone-rubber interposition arthroplasty. The follow-up period averaged 15; three years with a ten-year minimum. Although the procedure provided early pain relief in most thumbs, all but two had mild to severe pain at follow-up. The average range of post-operative palmar abduction was 23 degrees. The average post-operative grip strength was 9.5 kg. Both tip and key pinch between thumb and index finger averaged about 50% that of normal subjects. Dislocation of the implant occurred in two joints and breakages in five. Bony erosions around the implant, which we attributed silicone synovitis, were found in four thumbs. The indications for silicone-rubber interposition arthroplasty for OA of the thumb CMC joint should be severely restricted as these produced unsatisfactory long-term results.

Activities of Daily Living↗
PubMed2005

Treatments of osteoarthritis of the distal radioulnar joint: long-term results of three procedures.

Sixty-one wrists in 61 patients with osteoarthritis of the distal radioulnar joint treated by three consecutive procedures (20 Darrach, 25 Sauvé-Kapandji and 16 hemiresection-interposition arthroplastic procedures) were retrospectively evaluated. We preferred to perform Darrach's procedure in even the early stages of osteoarthritis of the distal radioulnar joint prior to introduction of Sauvé-Kapandji and hemirestion-interposition arthroplastic procedures. Subsequently the hemirestion-interposition arthroplasty was indicated when the triangular fibrocartilage cartilage was intact or could be reconstructed and the Sauvé-Kapandji when the triangular fibrocartilage complex could not be reconstructed or there was positive ulnar variance of more than 5 mm even though the triangular fibrocartilage complex was functional. Patient's age at operation averaged 59.8 years. There were 36 men and 25 women. There were 38 primary and 23 secondary osteoarthritis cases. Post-operative pain, range of motion, grip strength, return to work status; and radiographic results were evaluated. At the five- to 14-year (average, ten years) follow-up evaluation, relief of pain from Darrach procedure was inferior to the Sauvé-Kapandji procedure and hemiresection-interposition arthroplasty although this was not statistically significant. After both the Sauvé-Kapandji procedure and hemiresection-inteposition arthroplasty, post-operative improvements in flexion and extension of the wrist had statistical significance. Post-operative improvements in pronation and supination of the forearm showed statistical significances after all procedures. Improvements of post-operative grip strength and return to an original job in the Sauvé-Kapandji procedure and hemiresection-interposition arthroplasty were statistically superior to those with a Darrach's procedure. There were many post-operative complications following the Darrach's procedure. Darrach's procedure is better indicated for severe osteoarthritic changes of the distal radioulnar joint in elderly patients. We believe the operative indications between the Sauvé-Kapandji procedure and hemiresection-interposition arthroplasty are best determined prior to surgery by the existence and status of the triangular fibrocartilage complex and the amount of the positive ulnar variance.

Aged↗
PubMed2005

Effects of administration of exogenous growth factors on biomechanical properties of the elongation-type anterior cruciate ligament injury with partial laceration.

BACKGROUND: No studies have been conducted to clarify the in vivo effect of growth factor application on healing in the injured anterior cruciate ligament. HYPOTHESIS: Administration of exogenous growth factors significantly increases the structural properties of the injured anterior cruciate ligament. STUDY DESIGN: Controlled laboratory study. METHODS: Thirty-six rabbits were randomly divided into 4 groups of 9 animals each after an overstretched injury was made in the right anterior cruciate ligament. In group 1, no treatment was applied around the injured anterior cruciate ligament. In group 2, 0.2 mL fibrin sealant was applied around it. In group 3, 4 ng transforming growth factor-beta1 mixed with 0.2 mL fibrin sealant was applied. In group 4, 20 microg platelet-derived growth factor-BB mixed with 0.2 mL fibrin sealant was applied. Each rabbit was sacrificed at 12 weeks after the surgery. In addition, 9 knees randomly harvested from all the left knees were used to obtain normal control data. The femur-anterior cruciate ligament-tibia complex specimens were biomechanically and histologically evaluated. RESULTS: Concerning the maximum load and the stiffness, group 3 was significantly greater than groups 1 and 2, whereas there were no significant differences among groups 1, 2, and 4. Groups 1, 2, 3, and 4 were significantly lower than the control group. CONCLUSIONS: The application of 4 ng transforming growth factor-beta1 significantly enhances healing in the injured anterior cruciate ligament. CLINICAL RELEVANCE: Administration of certain growth factors is of value to be studied as one of the future therapeutic options for the overstretched anterior cruciate ligament injury.

Animals↗
PubMed2005

Chiari pelvic osteotomy for advanced osteoarthritis in patients with hip dysplasia.

BACKGROUND: It is not clear whether a Chiari pelvic osteotomy performed for the treatment of advanced osteoarthritis can delay the need for total hip arthroplasty. We present the mid-term results of the Chiari pelvic osteotomy performed for the treatment of Tönnis grade-3 osteoarthritis (large cysts, severe narrowing of the joint space, or severe deformity or necrosis of the head with extensive osteophyte formation), with a particular focus on whether this procedure can delay the need for total hip arthroplasty. METHODS: We followed thirty-two hips in thirty-one patients with Tönnis grade-3 osteoarthritis who had refused total hip arthroplasty and had been treated with a Chiari pelvic osteotomy. The mean age at the time of surgery was 35.2 years. The mean duration of follow-up was 11.2 years, at which time clinical evaluation with the Harris hip score and radiographic evaluation were performed. RESULTS: The average Harris hip score improved from 52 points preoperatively to 77 points at the time of follow-up; the average pain score improved from 20 to 31 points. Three hips with a hip score of <70 points required total hip arthroplasty. With a hip score of <70 points as the end point, the cumulative rate of survival at ten years was 72%. The clinical outcome was significantly influenced by the preoperative center-edge angle (p = 0.004), the preoperative acetabular head index (p = 0.039), achievement of the appropriate osteotomy level (p = 0.011), and superior migration (p = 0.009) and lateral migration (p = 0.026) of the femoral head. CONCLUSIONS: Although the clinical results were inferior to those of total hip arthroplasty, Chiari pelvic osteotomy may be an option for young patients with advanced osteoarthritis who prefer a joint-conserving procedure to total hip arthroplasty and accept a clinical outcome that is predicted to be less optimal than that of total hip arthroplasty. Moderate dysplasia and moderate subluxation without complete obliteration of the joint space and a preoperative center-edge angle of at least 10 degrees are desirable selection criteria.

Hip Dislocation, Congenital↗
PubMed2005

Multidirectional flexibility analysis of cervical artificial disc reconstruction: in vitro human cadaveric spine model.

OBJECT: This in vitro experimental study was conducted to investigate the initial biomechanical effect of artificial intervertebral disc replacement in the cervical spine. The multidirectional flexibility of replaced and adjacent spinal segments were analyzed using a cadaveric cervical spine model. METHODS: The following three cervical reconstructions were sequentially performed at the C5-6 level after anterior discectomy in seven human cadaveric occipitocervical spines: anterior artificial disc replacement with a bioactive three-dimensional (3D) fabric disc (FD); anterior iliac bone graft; and anterior plate fixation with iliac bone graft. Six unconstrained pure moments were applied with a 6-df spine simulator, and 3D segmental motions at the operative and adjacent segments were measured with an optoelectronic motion measurement system. The 3D FD group demonstrated statistically equivalent ranges of motion (ROMs) when compared with intact values in axial rotation and lateral bending. The 45% increase in flexion-extension ROM was demonstrated in 3D FD group; however, neutral zone analysis did not reach statistical significance between the intact spine and 3D FD. The anterior iliac bone graft and iliac bone graft reconstructions demonstrated statistically lower ROMs when compared with 3D FD in all loading modes (p < 0.05). The adjacent-level ROMs of the 3D FD group demonstrated nearly physiological characteristics at upper and lower adjacent levels. Excellent stability at the interface was maintained during the whole testing without any device displacement and dislodgment. CONCLUSIONS: The stand-alone cervical 3D FD demonstrated nearly physiological biomechanical characteristics at both operative and adjacent spinal segments in vitro, indicating an excellent clinical potential for cervical artificial disc replacement.

Bone Plates↗
PubMed2005

Vertebral osteonecrosis associated with sarcoidosis. Case report.

Sarcoidosis is a systemic disease commonly affecting lung, skin, or eye. Sarcoidosis involved with osseous structures occurs in approximately 5% of patients, usually involving small bones. Spinal sarcoidosis is extremely rare. The authors report on a man in whom examination of a subclavicular lymph node biopsy specimen and its spinal involvement had established a diagnosis of sarcoidosis and who had undergone steroid therapy. Despite intensive conservative treatment, the authors observed progressive collapse of L-2 requiring spinal decompressive and reconstructive surgeries. Histological evaluation of the collapsed vertebra did not show the typical noncaseating granuloma; rather, the authors observed osteonecrosis of the entire L-2 structure without reactive cellular activities. Other potential diagnoses including infectious disease, metastatic spinal tumor, and osteoporotic vertebral collapse were excluded based on laboratory data, imaging studies, and pathological findings. Complete necrosis of the entire L-2 vertebra in this case can be considered as a rare clinical manifestation of spinal sarcoidosis. Because of osteopenia and systemic bone fragility, combined anterior-posterior spinal reconstructive surgery was performed to restabilize the severely damaged spine.

Diagnosis, Differential↗
PubMed2004

Cervical spine injuries associated with lateral mass and facet joint fractures: new classification and surgical treatment with pedicle screw fixation.

To clarify the injury pattern, initial spinal instability, degree of discoligamentous injuries in cervical lateral mass and facet joint fractures, we retrospectively analyzed radiological parameters and introduced a new classification for these injuries. Surgical treatment was performed with cervical pedicle screw fixation (CPS), and overall neurological and radiological outcome was evaluated with a minimum follow-up period of 2 years. Lateral mass fractures were divided into the following four subtypes: separation, comminution, split, and traumatic spondylolysis. The sagittal and frontal alignments were evaluated at both mainly injured and adjacent spinal segments on radiographs. The initial discoligamentous injuries were investigated on magnetic resonance imaging in terms of their frequencies, subtype of injuries, and involved spinal levels. Anterior translation of fractured vertebra was demonstrated in 77% of lateral mass fractures, while 24% of anterior translation was observed, even in cephalad-adjacent vertebrae. On magnetic resonance imaging, signal changes in anterior longitudinal ligament (ALL) and intervertebral disc were demonstrated in 76% of caudal segments and 24% of cephalad segments adjacent to fractured vertebra of lateral mass fractures. The subtype analyses of lateral mass fractures demonstrated high rates of anterior translation in separation, split, and traumatic spondylolisthesis, as well as significant coronal malalignment in comminution and split types (p<0.05). Thirty-one patients underwent surgical treatments using a cervical pedicle screw fixation. The CPS provided the superior capability of deformity correction without pseudoarthrosis, as well as excellent neurological recovery. The average numbers of stabilized segments were minimized without serious complications. In separation, facet joint fracture, and fractures with mild lateral mass comminution, the single level posterior fixation can be considered. The significant unstable injuries of split and comminution type with coronal malalignment can be treated with exclusive two-level posterior stabilization with CPS. The initial evaluation of fracture subtypes helps to successfully minimize the stabilized spinal segment.

Adolescent↗
PubMed2004

Iliac crest reconstruction with a bioactive ceramic spacer.

This study aimed to investigate the long-term clinical results of the apatite wollastonite-containing glass ceramic (AWGC) iliac spacer and to discuss its efficacy in reconstruction of the bone graft donor site at the iliac crest. Thirty-one patients were studied for more than 10 years. All patients underwent anterior spinal fusion using autogenous tricortical iliac bone graft. After harvest of tricortical iliac bone graft, an AWGC iliac spacer ranging from 15 mm to 70 mm in length was press-fitted into the gap. Long-term clinical results were obtained from radiological and blood examinations. Thirty patients (97%) were satisfied with the spacer. There was new bone formation around the spacer on the radiograph. There was no abnormal silicon concentration in blood examinations. AWGC iliac spacer appears to be useful in the reconstruction of harvested iliac crest. New bone formation occurs, reducing the defect size.

Adolescent↗
PubMed2004

Inhibition of joint inflammation and destruction induced by anti-type II collagen antibody/lipopolysaccharide (LPS)-induced arthritis in mice due to deletion of macrophage migration inhibitory factor (MIF).

OBJECTIVE: Previous studies have demonstrated that neutralization of macrophage migration inhibitory factor (MIF) by anti-MIF antibody decreases joint destruction in the collagen-induced arthritis model. The present study was undertaken to investigate whether selective deletion of MIF inhibits inflammation and joint destruction of the anti-type II collagen antibody (anti-CII Ab)/lipopolysaccharide (LPS)-induced arthritis in mice, in order to determine the role of this cytokine in inflammatory arthritis. DESIGN: Anti-CII Ab/LPS-induced arthritis was induced in MIF-deficient and wild-type mice. The effects of anti-MIF polyclonal antibody administration on anti-CII Ab-induced arthritis were also evaluated. RESULTS: The expression of MIF protein and mRNA was induced in anti-CII Ab/LPS-induced arthritis joint tissues. Histopathological arthritis scores for synovial inflammation induced by anti-CII Ab/LPS -induced arthritis were significantly decreased in anti-MIF Ab-treated mice and in MIF-deficient mice compared to wild-type mice. In addition, mRNA levels of MMP-13 and MIP-2 in anti-CII Ab/LPS-induced arthritis joint tissues were significantly reduced in MIF-deficient mice compared to wild-type control mice. CONCLUSIONS: These results indicate that MIF plays a critical role in inflammation and joint destruction in the anti-CII Ab/LPS-induced arthritis model in mice, in part via induction of MMP-13 and neutrophil infiltration through the induction of MIP-2.

Animals↗
PubMed2004

A biomechanical analysis of metastatic vertebral collapse of the thoracic spine: a sheep model study.

STUDY DESIGN: This is a biomechanical study using sheep thoracic spine to investigate the probability of mechanical failure of the thoracic spine with various sizes or locations of tumor metastasis. OBJECTIVE: The objectives of this study were to investigate biomechanical effects of not only tumor sizes within the thoracic vertebral body but also its involvement of other spinal components on the probability of mechanical failures of the thoracic spine. SUMMARY OF BACKGROUND DATA: There have been no experimental studies concerning mechanical influences of destruction of costovertebral joint or posterior elements as well as vertebral body on the load-bearing capacity of the thoracic spine. METHODS: Ninety-nine fresh sheep thoracic spine specimens with ribs were used (T7-T9, T10-T12). Within vertebral bodies of 39 specimens, only trabecular defects were created in different sizes. In other 48 specimens, not only vertebral body defects that were 40% to the cross-sectional area of the vertebral body but also additional destruction of costovertebral joint, pedicle, and facet joint were created. All specimens were subjected to destructive biomechanical testing. RESULTS: The failure load decreased as the defect size in the vertebral body increased. A negative linear correlation was observed between the failure load and the size of vertebral body defect (r = 0.782). With 40% cross-sectional defect in the vertebral body, additional costovertebral joint destruction brought 25% reduction of the failure load, which was statistically significant. CONCLUSION: The load-bearing capacity of metastasized vertebrae in the thoracic spine was proportionally decreased when the defect size in the vertebral body increased. Destruction of costovertebral joint significantly increased the probability of vertebral collapse.

Animals↗
PubMed2004

Increased expression of macrophage migration inhibitory factor during fracture healing in rats.

We previously reported that macrophage migration inhibitory factor (MIF) is expressed in osteoblasts in murine calvarial bone, and that MIF upregulates the expression of matrix metalloproteinase (MMP)-13 mRNA in osteoblasts and chondrocytes; however, its pathophysiological functions in bone have not been well understood. In this study, we used a rat femoral fracture model to examine the expression of MIF during the fracture healing process. Semiquantitative reverse transcription-polymerase chain reaction revealed that MIF mRNA was increased throughout the healing process. The level of MIF mRNA reached a maximum at day 4 postfracture, while MMP-13 mRNA became maximal at day 14 postfracture. Immunohistochemical analysis showed that MIF protein was present in the granulation tissues formed at the fracture site on day 4. On days 7 and 10, MIF was detected in the thickened periosteum, in osteoblastic cells that were present within the intramembranously formed bone under the thickened periosteum, and in chondrocytes within the cartilaginous callus. From day 14 to day 28, MIF was present in chondrocytes within the callus, although the level of MIF declined gradually over this period. On days 7 to 14, MMP-13 was also detected in osteoblastic cells within the intramembranously formed bone and in chondrocytes within the cartilaginous callus. The immunoreactivity for MMP-13 within chondrocytes decreased on days 21 and 28. These results suggest the possibility that MIF plays an important role in fracture healing in association with proliferation of stromal cells, and the induction of MMP-13 in osteoblasts or chondrocytes.

Animals↗
PubMed2004

A retrospective radiographic analysis of subaxial sagittal alignment after posterior C1-C2 fusion.

STUDY DESIGN: Subaxial sagittal alignment following atlantoaxial (A-A) posterior fusion was investigated retrospectively in patients with A-A subluxation. OBJECTIVES: To evaluate the association between A-A fusion angle and postoperative subaxial sagittal alignment and to determine the optimal fusion angle for preservation of physiologic subaxial alignment. SUMMARY OF BACKGROUND DATA: A-A posterior fusion has been used for patients with A-A instability and provided satisfactory clinical results. However, there are patients showing unexpected development of subaxial kyphosis after surgery. The reasons for subaxial kyphosis after A-A fusion remain unclear. METHODS: Seventy-six patients with A-A subluxation who underwent several types of posterior A-A fusion were involved. There were 46 women and 30 men. The causes of A-A subluxation were rheumatoid arthritis in 47, trauma in 16, os odontoideum in 8, and unknown in 5. The methods of posterior fusion consisted of Magerl procedure with posterior wiring in 51, Brooks wiring in 18, and Halifax clamp in 7. Angles at C1-C2, C2-C7, and C1-C7 in the neural position were measured before surgery and at the final follow-up to find out any association between postoperative C2-C7 angle and the other radiologic parameters. The association between O-C1 range of motion and C2-C7 angle was also investigated. RESULTS: The mean angles of C1-C2, C2-C7, and C1-C7 before surgery were 18.4 degrees, 14.5 degrees, and 32.9 degrees, respectively. Those at the final follow-up were 26.0 degrees, 5.5 degrees, and 31.5 degrees, respectively. These results indicated that C1-C2 fixation in a hyperlordotic position led to a subaxial kyphosis after surgery. Statistics showed that there was a linear association between the C1-C2 lordotic fixation angle and the C2-C7 kyphotic angle. CONCLUSIONS: Surgical fixation of A-A joint in a hyperlordotic position will lead the lower cervical spine to a kyphotic sagittal alignment after surgery. To maintain the physiologic sagittal alignment of the subaxial cervical spine, C1-C2 should not be fixed in a hyperlordotic position.

Atlanto-Axial Joint↗