Safe placement of pedicle screws without jeopardizing neurovascular structures medially and anteriorly is important during spine surgery. Inferior breach of pedicle is also dangerous due to low margin of error. Lumbar morphology and identical pedicle orientation at L1 to L5 shown on CT scan of young Taiwanese patients (90 patients) were analyzed and compared with findings reported for Caucasian subjects. Previously reported techniques were employed to quantitatively elucidate the parameters regarding lumbar morphology and identical pedicle orientation at each vertebra. The parameters for pedicle angle (PA), pedicle diameter (PD), pedicle axis distance (PAD), midline axis distance (MAD), transverse pedicle axis distance (TPAD) and transverse intertangential angle (TITA) were measured. Taiwanese subjects had different PA, PD, PAD, MAD at L1 to L5 and TITA at L3 to L5 compared with Caucasian subjects. L5 had the most convergent pedicle axis, the widest PD and the shortest antero-posterior axis morphology. This study provides detailed information for identifying pedicle orientation during pedicle screw placement and elucidate racial differences in lumbar morphology and pedicle orientation between Taiwanese and Caucasian populations.

Involvement in cervical ligamentum flavum is a rare manifestation of the calcium pyrophosphate dihydrate deposition disease. Only few cases of this condition have been reported. We revealed eighteen cases of CPPD in cervical ligamentum flavum that diagnosed at a single medical center. In our case series, clinical characteristics and magnetic resonance imaging findings of patients are described. We retrospectively reviewed the medical charts and imaging studies of the eighteen patients with pseudogout attack of the cervical ligamentum flavum. In addition, we discussed the differences between this disease and ossification of ligamentum flavum in image manifestations. There were fourteen men and four women aged between 59 and 87 years. Diabetes mellitus and hypertension were the most common comorbidities. Myelopathy and neck pain were presented in most patients. C4–5 and C5–6 were attacked most frequently, and multiple- rather than single-level involvement could be observed in our series. “Acute on chronic phenomenon” was a specific magnetic resonance image finding in patients whose symptom durations were between 2 to 5 months. Compared to ossification of ligamentum flavum, calcium pyrophosphate dihydrate crystal deposition had different image signs, including morphology, side of the involved ligament, no continuity with the lamina, acute on chronic phenomenon, and presence of retro-odontoid mass. Nodular calcifications in cervical ligamentum flavum raise highly suspicion for calcium pyrophosphate dihydrate deposition and must be diagnosed by histological examination and polarized light microscopy. This disease is different from ossification of ligamentum flavum, and it could be recognized by specific image features.

Tips & Techniques Hsi-Hsien Lin, MD; Chien-Shun Wang, MD; Cheng-Fong Chen, MD; Chao-Ching Chiang, MD; Ching-Kuei Huang, MD; Wei-Ming Chen, MD; Chien-Lin Liu, MD The authors retrospectively evaluated the effects of a single cortical screw in the open reduction and internal fixation of displaced distal clavicle fractures. Fifteen patients without associated acromioclavicular joint dislocation were treated by open reduction and internal fixation with a single cortical screw (4.5-mm diameter, 60-mm length) between 2004 and 2011. Mean follow-up was 39.2 months (range, 13–84 months). Reduction with a fracture gap of less than 1 mm and solid union were achieved in all cases. Delayed superficial infection developed in 1 patient. All other patients had good to excellent final Constant-Murley functional results. The authors are from the Department of Orthopedics & Traumatology (H-HL, C-SW, C-FC), Taipei Veterans General Hospital, and the School of Medicine (C-CC, C-KH, W-MC, C-LL), National Yang-Ming University, Tai-wan, Republic of China. The authors have no relevant financial relationships to disclose. Correspondence should be addressed to: Ching-Kuei Huang, MD, Department of Orthopedics & Traumatology, Taipei Veterans General Hospital, No. 201, Sec 2, Shipai Rd, Beitou District, Taipei City, Taiwan 11217, Republic of China (tmtckhuang@gmail.com). Displaced distal clavicle fractures are notorious for high rates of nonunion following treatment, which can lead to pain and impaired function of the shoulder girdle and upper limb.^1–3 Thus, open reduction and internal fixation is recommended most often to treat this unstable injury. Numerous methods of fixation are suggested, but many require an extensile exposure and involve high costs.^1–3 Intramedullary fixation with a Knowles pin has been used to reduce and fix distal clavicle fractures and has resulted in good reduction in some cases.⁴ Extra-articular⁵ and transacromial⁶ Knowles pin fixation has also been reported to produce excellent results. However, hardware complications exist, including loss of reduction, distal skin irritation with infection, and lateral pin migration.⁷ Since 2004, the current authors have been using a single cortical screw to treat displaced distal clavicle fractures in select patients. In this study, the authors present this technique and evaluate the results retrospectively. Between 2004 and 2011, fifteen cases of displaced distal clavicle fractures were managed with open reduction and internal fixation with a single cortical screw (4.5-mm diameter, 60-mm length) after obtaining informed consent from all patients. Indications included transverse or short oblique fractures and intact distal fragment between 10 and 25 mm in length. Associated separation of the acromioclavicular joint was carefully checked clinically and radiographically before treatment because 20% of displaced distal clavicle fractures may have disruption of the acromioclavicular ligaments.⁸ Patients with open fractures, pathological fractures, previous surgeries on the affected clavicle or shoulder, gross neurovascular injury, intra-articular comminution, or associated acromioclavicular joint injuries were excluded. All surgeries were performed by the same orthopedic surgeon (C.-K.H.). The study group comprised 11 men and 4 women with a mean age of 47.2 years (range, 20–78 years) at injury. All patients have complete data from the final evaluation. Five patients injured their left side and 10 injured their right side. All cases were managed within 1 week of injury and were evaluated preoperatively with plain radiography, including 1 chest posteroanterior view and 1 shoulder anteroposterior view. Plain radiographs are sufficient to confirm the diagnosis and to provide information regarding fracture classification.² Other associated injuries were managed as needed without surgical intervention. All patients used an arm sling for 4 weeks postoperatively. Active shoulder range of motion was allowed as tolerated immediately postoperatively. Follow-up examinations were performed 2 weeks postoperatively and then every month until union was confirmed by radiographs. Functional evaluation using the Constant-Murley score and subscapularis test was performed on an outpatient basis before screw removal. All fractures were treated while the patient was under general anesthesia in a beach-chair position. First, a horizontal incision approximately 4 cm in length was made between the acromioclavicular joint and the medial end of the palpated fracture site. It is important to minimize disturbances to the coracoclavicular ligament and acromioclavicular joint capsule during dissection and prevent dispersion of the fragments in the capsule envelope. With minimal periosteal stripping, the fracture ends and superior acromioclavicular ligament of the joint capsule were exposed (Figure 1). Reduction was performed under direct visualization with a reduction clamp. Figure 1: Intraoperative photograph showing the fracture ends (vertical arrow) and acromioclavicular joint capsule (horizontal arrow) exposed without soft tissue stripping. The intramedullary cavities of both fragments were then predrilled with a 3.2-mm drill bit through the distal fragment to the proximal fragment from the entry point posterior to the acromioclavicular joint capsule in an anteromedial direction. A 4.5-mm-diameter, 60-mm-long AO/ASIF cortical screw was inserted under reduction from the entry point in the posterolateral corner of the distal fragment. Without penetrating the proximal fragment, the screw head was pressed tightly against the posterolateral periosteum (Figure 2). Figure 2: Intraoperative photograph showing the entry point posterior to the acromioclavicular joint capsule (vertical arrow) and the intact acromioclavicular ligament (horizontal arrow). The coracoclavicular ligaments were not repaired because the acromioclavicular ligament was spared and remained intact throughout the procedure. Fixation stability was tested against free shoulder joint range of motion without displacement after fixation. The wound was irrigated and closed with appropriate sutures. The final position of the screw is shown in Figure 3. Figure 3: Illustration showing the cortical screw placed intramedullary from the posterolateral aspect of the distal fragment. All 15 fractures were classified as Neer type II fractures: 5 type IIA and 10 type IIB. In the 15 procedures performed, mean intraoperative blood loss was less than 20 cc (range, 5–20 cc), with a mean operative time of 26 minutes (range, 20–48 minutes). Mean hospital stay was 3 days (range, 2–5 days). All 15 cases achieved union with congruent reduction at a mean of 11 weeks (range, 6–16 weeks). Mean follow-up was 39.2 months (range, 13–84 months). One case of superficial wound infection was noted at final follow-up. All patients had good or excellent functional results, with an overall mean Constant-Murley score of 96 (range, 92–100) at final follow-up and a score difference of less than 12 compared with the healthy side of shoulder. Final radiographic evaluation showed anatomic congruent reduction (less than 1 mm displacement) and solid union in all cases. The radiographs of a 20-year-old woman are shown in Figure 4. All 5 associated injuries healed without sequelae. Figure 4: Anteroposterior radiograph of a Neer type 2 fracture in a 20-year-old woman after a motor vehicle collision (A). Anteroposterior radiograph 1.5 years postoperatively showing solid union with an excellent functional result (B). Anteroposterior radiograph 2.5 years postoperatively and 1 year after screw removal (C). No iatrogenic neurovascular injury developed in this series. No subcutaneous hematoma, distal skin irritation, or screw migration were observed. All patients had a negative supraspinatus test with intact rotator cuff function. One (6.6%) postoperative complication of superficial wound infection was treated successfully. Distal third clavicle fractures often result from a direct, high-energy force, such as motor vehicle collisions, in younger patients and falling accidents in elderly patients. The distal fragments are usually small and comminuted, and it is difficult to achieve secure fixation and early mobilization. Conservative treatment of these fractures often fails.⁹ Several surgical methods have been reported for stabilizing this unstable fracture, especially with the development of the locking or hook plate system.^3,10 Hook plating techniques handle these small fragments well but may cause general complications, such as infection, loss of reduction, hematoma, nonunion, and specific complications, including acromial fracture at the hook, hook cutout, rotator cuff tear, and subacromial impingement.³ Removal is suggested immediately after bony union in cases of acromial osteolysis or fracture.⁷ Other possible complications include subclavian vessel and supraclavicular nerve penetration and skin erosion.⁹ The extensile soft tissue stripping and weakness of bone after removal are also concerns with plating techniques. In a study by Fann et al,⁶ transacromial intra-articular Knowles pin fixation was reported with satisfactory results, but acromioclavicular joint arthrosis may cause concerns. Therefore, this approach may be reserved for patients with acromioclavicular joint instability.¹¹ In another study, transacromial extra-articular Knowles pin fixation indirectly fixed the fracture with suture augmentation; however, a high rate (32%) of lateral pin migration was observed.⁵ In a study by Jou et al,⁴ intramedullary extra-articular fixation of the fracture from the posterolateral corner of the clavicle with a Knowles pin was successful in 12 patients, but 2 (16.7%) patients developed distal skin irritation. The lag effect of Knowles pins also limits pin tightening and makes immediate range of motion risky. Cortical screws with a 4.5-mm diameter are robust enough to withstand the forces generated across the fracture site during union. Furthermore, the screw diameter is larger than that of a Knowles pin, so the fixation is more rigid. Mean length of the distal clavicle fragment was approximately 28.5 mm.⁴ In the current study, all of the distal fragments were smaller than 3.0 cm. Thus, a 4.5-mm-diameter, 60-mm-long cortical screw may provide more secure fixation than a 3.2-mm Knowles pin. The cortical screw head is smaller than the hub of a Knowles pin. The low profile of the screw head solves the problem of distal skin irritation noted with Knowles pins, but it is still palpable. Furthermore, its blunt tip improves proximal skin irritation, especially in slender female patients. The advantages of intramedullary fixation include a smaller incision, reduced soft tissue stripping with a shorter operative time, and the relative protection of the supraclavicular nerves. The screw’s all-threaded structure, with no lag effect, allows for immediate and full passive range of motion and provides enough load-sharing mechanical strength during union. In the current series, no hardware migration or breakage was observed, which may be a disadvantage of intramedullary fixation.¹² The cortical screws are inexpensive and available in most orthopedic units. The strengths of the current study include the follow-up duration and the use of a patient-oriented outcome. The limitations of this study include a small case number and its retrospective nature. A study involving a larger series is warranted. In displaced distal clavicle fractures without intra-articular comminution or associated acromioclavicular joint dislocation, a single cortical screw with a 4.5-mm diameter is useful and effective in reduction and fixation. The medical cost is low and the procedure is minimally invasive, with a small amount of blood loss and a short hospital stay. Figure 1: Intraoperative photograph showing the fracture ends (vertical arrow) and acromioclavicular joint capsule (horizontal arrow) exposed without soft tissue stripping. Figure 2: Intraoperative photograph showing the entry point posterior to the acromioclavicular joint capsule (vertical arrow) and the intact acromioclavicular ligament (horizontal arrow). Figure 3: Illustration showing the cortical screw placed intramedullary from the posterolateral aspect of the distal fragment. Figure 4: Anteroposterior radiograph of a Neer type 2 fracture in a 20-year-old woman after a motor vehicle collision (A). Anteroposterior radiograph 1.5 years postoperatively showing solid union with an excellent functional result (B). Anteroposterior radiograph 2.5 years postoperatively and 1 year after screw removal (C). 10.3928/01477447-20130222-04 Healio is intended for health care provider use and all comments will be posted at the discretion of the editors. We reserve the right not to post any comments with unsolicited information about medical devices or other products. At no time will Healio be used for medical advice to patients.

Gouty arthritis is the most common form of inflammatory arthritis and flares frequently after surgeries. Such flares impede early patient mobilization and lengthen hospital stays; however, little has been reported on gout flares after spinal procedures. This study reviewed a database of 6439 adult patients who underwent thoracolumbar spine surgery between January 2009 and June 2021, and 128 patients who had a history of gouty arthritis were included. Baseline characteristics and operative details were compared between the flare-up and no-flare groups. Multivariate logistic regression was used to analyze predictors and construct a predictive model of postoperative flares. This model was validated using a receiver operating characteristic (ROC) curve analysis. Fifty-six patients (43.8%) had postsurgical gout flares. Multivariate analysis identified gout medication use (odds ratio [OR], 0.32; 95% confidence interval [CI], 0.14–0.75; p = 0.009), smoking (OR, 3.23; 95% CI, 1.34–7.80; p = 0.009), preoperative hemoglobin level (OR, 0.68; 95% CI, 0.53–0.87; p = 0.002), and hemoglobin drop (OR, 1.93; 95% CI, 1.25–2.96; p = 0.003) as predictors for postsurgical flare. The area under the ROC curve was 0.801 (95% CI, 0.717–0.877; p < 0.001). The optimal cut-off point of probability greater than 0.453 predicted gout flare with a sensitivity of 76.8% and specificity of 73.2%. The prediction model may help identify patients at an increased risk of gout flare.