Evaluation of peri-prosthetic radiolucent lines surrounding the cementless femoral stem using digital tomosynthesis with metal artifact reduction: a cadaveric study in comparison with radiography and computed tomography

Computed Tomography With Implant Movement Analysis in the Work-Up of Painful Total Hip Prostheses

BACKGROUND

Diagnosing aseptic loosening following total hip arthroplasty is challenging. Computed tomography (CT)-guided implant movement analysis (CT-IMA) overlays two CT scans of a stressed total hip prosthesis to evaluate for micromotion. The purpose of this study was to evaluate this technology in identifying clinically stable and unstable total hip prostheses.

METHODS

Plain radiographs and CT-IMA scans of 80 patients with painful total hip prostheses were evaluated. Standard radiographs demonstrating 1- to 2-mm circumferential radiolucent lines within the modified Gruen, or Delee and Charnley zones, or subsidence were considered loose. A CT-IMA scan demonstrating implant motion > 0.5 mm was generally considered loose. Patients were categorized by implant stability based on plain radiographs and CT-IMA scans. Hip Dysfunction and Osteoarthritis Outcome Score for Joint Replacement (HOOS, JR) scores were calculated for each group from the initial to the final follow-up. Statistical analysis was performed with two-tailed paired t-tests.

RESULTS

There were 66 patients who were categorized into the radiographically Stable-IMA Stable group (Group 1), six into the radiographically Loose-IMA Stable group (Group 2), and eight into the radiographically Loose-IMA Loose group (Group 3). Within Group 1, HOOS, JR scores improved from 49.5 ± 18.4 to 64.2 ± 18.9 (P = 0.004). The 14 patients who underwent revision surgery had well-fixed components. Within Group 2, HOOS, JR scores improved from 57.7 ± 19.7 to 69.1 ± 21.5 (P = 0.01). The two patients who underwent revision surgery had well-fixed components. Within Group 3, HOOS, JR scores improved from 45.5 ± 18.1 to 71.8 ± 15.4 (P = 0.04). The seven patients who underwent revision surgery had loose components and one patient was lost to follow-up.

CONCLUSIONS

A CT-IMA better identified patients who had stable total hip prostheses than standard radiographs, demonstrating its value in the workup of a painful total hip prosthesis.

Turned stem tension band technique in reverse total shoulder arthroplasty for proximal humeral fracture can achieve high tuberosity healing rates regardless of the vertical sutures

Background

The importance of tuberosity healing in reverse total shoulder arthroplasty for proximal humeral fractures (PHFs) has been recognized. The turned stem tension band (TSTB) technique has been applied to tuberosity repair, and high bone healing and low reduction loss rates have been reported. Vertical sutures were added to the original method to reinforce fixation. We hypothesized that vertical sutures would be unnecessary in case the supraspinatus tendon was resected. This study aimed to compare the TSTB technique with or without vertical suturing for PHFs and evaluate the rates of tuberosity healing and reduction loss.

Methods

Thirty five patients (vertical suture group: 18 cases and nonvertical suture group: 17 cases) underwent reverse total shoulder arthroplasty for complex PHFs using the TSTB technique. We evaluated the postoperative range of motion, the American Shoulder and Elbow Surgeons score, tuberosity healing rates, and reduction loss.

Results

The vertical and nonvertical suture groups showed no significant difference in flexion (119 ± 33° vs. 124 ± 23°, P = .95), abduction (116 ± 35° vs. 115 ± 27°, P = .78), external rotation (27 ± 12° vs. 21 ± 8°, P = .16), internal rotation (6 ± 4° lumbar 3 level vs. 6 ± 4°, lumbar 3 level P = .87), the American Shoulder and Elbow Surgeons (77.3 ± 10.7 vs. 81.6 ± 6.3, P = .59), Numerical Rating Scale scores (1.2 ± 0.9 vs. 0.8 ± 0.9, P = .13), and tuberosity reduction loss (P = .34). The tuberosity healing rate in both groups was 100%.

Conclusion

The TSTB technique for PHFs provided high tuberosity healing and low reduction loss rates regardless of vertical sutures.

Association between the canal filling ratio and bone resorption in trabecular metal stems in reverse total shoulder arthroplasty: a radiographic analysis using tomosynthesis

Background

Several factors affect the incidence of osteopenia with cortical narrowing (CNO) in reverse shoulder arthroplasty. This study aimed to compare the incidence of CNO with different fixation methods (cemented or cementless) using a single implant (trabecular metal humeral stem) evaluated using tomosynthesis and to analyze the factors affecting the incidence of CNO for cementless stem fixation.

Methods

A total of 109 patients (cementless: 75 cases; cemented: 34 cases) who underwent reverse total shoulder arthroplasty were included in this study. The patients were divided into 2 groups (cementless or cemented), and the incidence of CNO was compared. In addition, patients in the cementless group were divided into 2 groups (canal filling ratio [CFR] of ≥ 0.7 or < 0.7), the incidence of CNO was compared, and the Cramer's coefficient of association between CNO and CFR > 0.7 (and 0.8) was calculated.

Results

No significant difference was observed in the incidence of CNO between the cementless and cemented groups (7/75 vs. 3/35, P value = 1.0). The association between CNO and the CFR using Cramer's coefficient of association showed that there were few correlations (coefficient: 0.14, P value = .59).

Conclusion

Cementless reverse total shoulder arthroplasty with a trabecular metal stem has a similar low incidence of CNO as cemented fixation, and the incidence of CNO with a trabecular metal stem was lower than that reported in previous studies. A CFR > 0.7 was not associated with the incidence of CNO.

Both angled bony-increased offset and metal-augmented baseplates provide satisfactory bone incorporation to the glenoid in reverse total shoulder arthroplasty: a radiographic evaluation using tomosynthesis

BACKGROUND

Angled bony-increased offset and metal-augmented baseplate have recently been used to achieve neutral to inferior inclination of the glenoid implant. Nonetheless, bone incorporation is difficult to evaluate using computed tomography or other conventional methods owing to the presence of metal artifacts; therefore, whether bone incorporation between the grafted bone and glenoid or between the graft and baseplate implant can be achieved remains unclear. Several studies have reported the effectiveness of tomosynthesis in reducing metal artifacts for the evaluation of implant loosening, bone resorption, and spot welds. We aimed to evaluate and compare the bone incorporation rates between angled bony-increased offset and metal-augmented implants using tomosynthesis with metal artifact reduction technology. We hypothesized that a high bone incorporation rate would be obtained with angled bony-increased offset and a metal-augmented baseplate.

METHODS

A total of 52 patients who underwent reverse total shoulder arthroplasty (TSA) with angled bony-increased offset and 42 patients who underwent reverse total shoulder arthroplasty with metal-augmented baseplate were assessed and followed up for a minimum of 2 years. The bone incorporation and implant loosening rates were compared between the 2 groups, and the sites of spot welds and trabeculation were recorded according to zones. Bone incorporation between the bone and prosthesis was defined as a confirmation of spot welds connecting the porous area and bone in more than three zones. Bone incorporation between the native bone and grafted bone was defined as an observation of trabeculation. Glenoid loosening was defined as the presence of at least 1 mm radiolucency around the prosthesis in more than 2 zones.

RESULTS

Both the angled bony-increased offset and metal-augmented baseplate groups achieved sufficient bone incorporation rates (98% [51/52 cases] vs. 100% [42/42 cases], P = 1.0) and low implant loosening rates (2% [1/52 cases] vs. 0% [0/42 cases], P = 1.0). Spot welds and trabeculation were likely to be confirmed in the lower parts of the glenoid.

CONCLUSION

The two groups did not show any significant differences regarding bone incorporation rates. Considering the complexity of performing the procedure with angled bony-increased offset, the use of a metal-augmented baseplate can serve as an alternative treatment to avoid superior inclination in reverse total shoulder arthroplasty.

Advances in Bone Joint Imaging-Metal Artifact Reduction

Numerous types of metal implants have been introduced in orthopedic surgery and are used in everyday practice. To precisely evaluate the postoperative condition of arthroplasty or trauma surgery, periprosthetic infection, and the loosening of implants, it is important to reduce artifacts induced by metal implants. In this review, we focused on technical advances in metal artifact reduction using digital tomosynthesis, computed tomography, and magnetic resonance imaging. We discussed new developments in diagnostic imaging methods and the continuous introduction of novel technologies to reduce metal artifacts; however, these innovations have not yet completely removed metal artifacts. Different algorithms need to be selected depending on the size, shape, material and implanted body parts of an implant. Future advances in metal artifact reduction algorithms and techniques and the development of new sequences may enable further reductions in metal artifacts even on original images taken previously. Moreover, the combination of different imaging modalities may contribute to further reductions in metal artifacts. Clinicians must constantly update their knowledge and work closely with radiologists to select the best diagnostic imaging method for each metal implant.

Imaging in Hip Arthroplasty Management Part 2: Postoperative Diagnostic Imaging Strategy

Hip arthroplasty (HA) is a frequently used procedure with high success rates, but 7% to 27% of the patients complain of persistent postsurgical pain 1 to 4 years post-operation. HA complications depend on the post-operative delay, the type of material used, the patient’s characteristics, and the surgical approach. Radiographs are still the first imaging modality used for routine follow-up, in asymptomatic and painful cases. CT and MRI used to suffer from metallic artifacts but are nowadays central in HA complications diagnosis, both having their advantages and drawbacks. Additionally, there is no consensus on the optimal imaging workup for HA complication diagnosis, which may have an impact on patient management. After a brief reminder about the different types of prostheses, this article reviews their normal and pathologic appearance, according to each imaging modality, keeping in mind that few abnormalities might be present, not anyone requiring treatment, depending on the clinical scenario. A diagnostic imaging workup is also discussed, to aid the therapist in his imaging studies prescription and the radiologist in their practical aspects.

New Evaluation Method for Bone Formation around a Fully Hydroxyapatite-Coated Stem Using Digital Tomosynthesis: A Retrospective Cross-Sectional Study

Digital tomosynthesis (DTS) is a new imaging technique derived from radiography, and its usefulness has been gradually reported in the field of orthopedic diagnosis in recent years. A fully hydroxyapatite (HA)-coated stem, which is used for total hip arthroplasty (THA), is a type of cementless stem that has been widely used recently and reported to have good results. However, stem loosening on plain radiographs is difficult to determine in some cases due to cancellous condensation around the stem. In this retrospective cross-sectional study, we compared the results of plain radiography versus DTS to evaluate the imaging findings after THA using a fully HA-coated stem. Twenty joints each in the 3 y and 1 y postoperative groups underwent plain radiography and DTS. On DTS, bone formation around the stem was confirmed in all cases; however, this formation was not reproducible on plain radiography, and there were cases in which the reaction could not be confirmed or cases with cancellous condensation resembling reactive lines. This reaction was not reproducible on plain radiographs, and in some cases, the reaction could not be confirmed, or there were cases with cancellous condensation that resembled reactive lines. Therefore, DTS was useful in the diagnosis of bone formation around the implant.