Compared to X-ray, three-dimensional computed tomography measurement is a reproducible radiographic method for normal proximal humerus

Long-term survival of resurfacing humeral hemiarthroplasty

INTRODUCTION

The indication for shoulder resurfacing arthroplasty is controversial, and survival of these implants is somewhat inconsistent. This study aimed to evaluate the long-term survivorship of resurfacing humeral head implants (RHHIs) and determine risk factors for complications and revisions.

MATERIALS AND METHODS

This retrospective cohort study consisted of 275 cases and two types of RHHIs. The survival rate was evaluated using the Kaplan-Meier method and Cox regression for risk factor analysis. Demographic factors were studied, and the change in the humerus centre of rotation (COR) was measured.

RESULTS

The mean follow-up time was 8.7 years (SD 2.7 months, range 2.8-15.9 years). The mean age of the patients was 67.6 years (SD 9.6, range 33.5-84.9). Ten-year cumulative RHHI survival was 94.1%. The cumulative estimate without any complication was 98.9% at 5 years, 80.0% at 10 years and at 15 years it was 61.5%. The most common complication was persistent pain in 13.8% of the RHHIs. The risk factors for complications and revisions were implant type, preoperative conditions and change of COR > 5 mm.

CONCLUSIONS

RRHIs showed excellent long-term survival, but many complications were found. The most common complication was persistent pain, which seemed to be caused by a change of COR and was more related to one type of implant.

Pre-operative virtual three-dimensional planning for proximal humerus fractures: A proof-of-concept study

Purpose

To (1) evaluate surgeon agreement on plating features (position and screw length) in virtual 3D planning software, (2) describe outcomes (fracture reduction, plate position, malpositioning of calcar screws and screw lengths) of plate fixations planned with routine pre-operative assessment (2D- and 3D CT imaging) and those planned with dedicated virtual 3D software of the same proximal humerus fracture.

Methods

Fourteen proximal humerus fractures were retrospectively reduced and fixed with virtual planning software by eight attending orthopaedic surgeons and compared to the true surgical fixation with post-operative computed tomography (CT) scans. Reduction differences were quantified using CT micromotion analysis.

Results

Intraclass correlation for screw lengths was 0.97 (95% CI: 0.96-0.98) and 0.90 (95% CI: 0.79-0.96) for plate position. Mean difference in total fracture rotation of the head between the virtual and conventional group was 22.0°. Plate position in the virtual planning group was 3.2 mm more proximal. There were no differences in inferomedial quadrant calcar screw positioning and, apart from the superior posterior converging screw, no significant differences in screw lengths.

Conclusion

Reproducibility on plate position and screw length with virtual planning software is adequate. Apart from fracture reduction, virtual planning yielded similar plate positions, screw malpositioning rates and lengths compared to routine pre-operative assessment.

Corrective Open-wedge Valgus Proximal Humerus Lengthening Osteotomy. Technique and Case Series

Symptomatic varus malunion after proximal humeral fractures is associated with weakness and painful limitation of shoulder range of motion. When there is conformity of the articular surface and no avascular necrosis, a head-preserving procedure is best indicated. Arthroscopic arthrolysis, subacromial decompression, and tuberoplasty have been described for the treatment of mild deformity. In cases with more severe deformity, corrective extracapsular lateral closing wedge valgus osteotomy has been reported as a reliable treatment option, in terms of both pain relief and improved function. While this procedure adequately restores rotator cuff tensioning, it is associated with a shortening of the lever arm to the deltoid muscle, secondary to a loss of humeral length. We describe our technique and results with a vascular-sparing, medial open-wedge osteotomy, using a structural allograft and lateral locking plate. In our opinion, this procedure is safe and effective, with the potential to improve functional outcomes in young and active patients.

Prediction of the Proximal Humerus Morphology Based on a Statistical Shape Model with Two Parameters: Comparison to Contralateral Registration Method

(1) Background: Complex proximal humerus fractures often result in complications following surgical treatment. A better understanding of the full 3D displacement would provide insight into the fracture morphology. Repositioning of fracture elements is often conducted by using the contralateral side as a reconstruction template. However, this requires healthy contralateral anatomy. The purpose of this study was to create a Statistical Shape Model (SSM) and compare its effectiveness to the contralateral registration method for the prediction of the humeral proximal segment; (2) Methods: An SSM was created from 137 healthy humeri. A prediction for the proximal segment of the left humeri from eight healthy patients was made by combining the SSM with parameters. The predicted proximal segment was compared to the left proximal segment of the patients. Their left humerus was also compared to the contralateral (right) humerus; (3) Results: Eight modes explained 95% of the variation. Most deviations of the SSM prediction and the contralateral registration method were below the clinically relevant 2 mm distance threshold.; (4) Conclusions: An SSM combined with parameters is a suitable method to predict the proximal humeral segment when the contralateral CT scan is unavailable or the contralateral humerus is unhealthy, provided that the fracture pattern allows measurements of these parameters.

Design of well-matched end-structure of anatomical proximal femoral locking plate based on computer-assisted imaging combined with 3D printing technology: a quality improvement study

BACKGROUND

The extramedullary locking plate system was the common internal fixation method for hip fractures. However, common plates were poorly matched to femur, which was because they were designed based on anatomical parameters of the Western populations. Therefore, the aim was to design an end-structure of the anatomical proximal femoral locking plate that closely matched the anatomy of the Chinese population.

MATERIALS AND METHODS

From January 2010 to December 2021, consecutive patients aged 18 years and older who underwent a full-length computed tomography scan of the femur were included. The end-structure (male and female model) of the anatomical proximal femoral locking plate was designed based on anatomical parameters of femurs that were measured in three-dimensional space using computer-assisted virtual technology. The match degree between the end-structure and femur were evaluated. Inter-observer and intra-observer agreement for the evaluation of match degree was assessed. The matching evaluation based on a three-dimensional printing model was regarded as the gold standard to assess the reliability.

RESULTS

A total of 1672 patients were included, with 701 men and 971 women. Significant differences were seen between male and female for all parameters of the proximal femur (all P <0.001). All match degree of end-structure was over 90%. Inter-observer and intra-observer agreement was almost perfect (all kappa value, >0.81). The sensitivity, specificity, and percentage of correct interpretation of matching evaluation in the computer-assisted virtual model was all greater than 95%. From femur reconstruction to completion of internal fixation matching, the process takes about 3 min. Moreover, reconstruction, measurement, and matching were all completed in one system.

CONCLUSIONS

The results showed that based on the larger sample of femoral anatomical parameters, a highly matching end-structure of anatomical proximal femoral locking plate for Chinese population could be designed with use of computer-assisted imaging technology.

Computed Tomography Does Not Improve Intra- and Interobserver Agreement of Hertel Radiographic Prognostic Criteria

Background and Objectives: Proximal humerus fractures are the second most frequent site of avascular necrosis (AVN), occurring in up to 16% of cases. The Hertel criteria have been used as a reference for the prediction of humerus head ischemia. However, these are based solely on the use of radiographs, which can make interpretation extremely difficult due to several reasons, such as the overlapping fragments, severity of the injury, and noncompliant acute pain patients. The objectives of the study were to evaluate the role of computed tomography (CT) in the interpretation of the Hertel criteria and to evaluate the intra- and interobserver agreement of orthopedic surgeons, comparing their area of expertise. Materials and Methods: The radiographs and CT scans of 20 skeletally mature patients who had fractures of the proximal humerus were converted to jpeg and mov, respectively. All images were evaluated by eight orthopedic surgeons (four trauma surgeons and four shoulder surgeons) in two different occasions. The intra- and interobserver agreement was assessed by using the Kappa coefficient. The level of significance was 5%. Results: There was a weak-to-moderate intraobserver agreement (κ < 0.59) for all examiners. Only the medial metaphyseal hinge greater than 2 mm was identified by 87.5% of evaluators both in the radiographic and CT examinations in the two rounds of the study (p < 0.05). There was no significant interobserver agreement (κ < 0.19), as it occurred only in some moments of the second round of evaluation. Conclusions: The prognostic criteria for humeral head ischemia evaluated in this study showed weak intra- and interobserver agreement in both the radiographic and tomographic evaluation. CT did not help surgeons in the primary interpretation of Hertel prognostic criteria used in this study when compared to the radiographic examination.

Fixed- vs. variable-angle humeral neck cut in anatomic total shoulder arthroplasty: a randomized controlled trial

BACKGROUND

Variable neck-shaft angle (NSA) stemmed humeral components have been incorporated into certain implant designs to better re-create normal anatomy in total shoulder arthroplasty (TSA). The purpose of this study was to determine if premorbid glenohumeral joint anatomy is better restored with a fixed- vs. variable-NSA prosthesis.

METHODS

A randomized controlled trial was performed including 50 patients with osteoarthritis indicated for primary anatomic TSA. Patients were randomized preoperatively to receive either a variable- (n = 26) or fixed-NSA (n = 24) prosthesis. Humeral neck cut in the variable-NSA group matched the patient's anatomic neck, with prosthetic NSA of 127.5°, 132.5°, and 137.5° available. Fixed-NSA cuts were made with an intramedullary guide of 132.5°. Preoperative and postoperative radiographs were evaluated for specific radiographic anatomic variables: NSA, head thickness, tuberosity-to-head height, head offset, articular arc, greater tuberosity offset, and center of rotation (COR). Postoperative radiographic criteria were compared between groups.

RESULTS

No differences were found between groups in demographics or preoperative radiographic measures. When comparing average difference in preoperative and postoperative measurements in the fixed-NSA group, the humeral head offset from the humeral shaft axis significantly decreased by 1.4 mm (P = .046), and the COR moved superiorly (3.0 mm, P = .002) without significant medialization or lateralization. In the variable angle group, humeral head offset decreased but did not reach significance (1.2 mm, P = .091), and the COR also moved superiorly (2.9 mm, P < .001) without significant medialization or lateralization. All remaining radiographic parameters did not significantly change from pre- to postoperative imaging. In comparing the fixed- and variable-NSA groups' net change from the premorbid measurements, no significant differences were found in tuberosity-to-head height, head offset, or COR position in both the horizontal and vertical planes.

CONCLUSIONS

Both fixed- and variable-NSA anatomic TSA humeral components demonstrate adequate restoration of premorbid anatomy radiographically.

3D-Analysis of the Proximal Humeral Anatomy Before and After Stemless Shoulder Arthroplasty-A Prospective Case Series Study

BACKGROUND

Stemless shoulder arthroplasty (SSA) is used to anatomically reconstruct proximal humerus geometry and preserve proximal humerus bone stock. The current literature lacks 3D-analysis of pre- and postoperative proximal humeral anatomy after SSA. The aim of this study was to prospectively analyze the humeral head anatomy using a computer-assisted topography mapping technique after SSA in relation to the preoperative status and the contralateral (not affected) side.

METHODS

Twenty-nine patients (mean age: 63.5 ± 11.7 years) affected by primary shoulder osteoarthritis and treated with SSA were included. Preoperative and postoperative CT scans of the affected and contralateral sites were analyzed regarding joint geometry. Clinical outcome was assessed by Constant and Disabilities of the Arm, Shoulder and Hand (DASH) score shortly before and one year after surgery.

RESULTS

Clinical outcome improved significantly. No correlation between clinical outcome and the evaluated anatomical parameters was found. There was a significant decrease of the humeral head height (p < 0.01) and radius (p = 0.03) in the preoperative versus the postoperative joint geometry. The comparison to the contralateral site showed also a significant decrease of the humeral head height (p < 0.01). All other parameters showed no significant differences.

CONCLUSION

Proximal humeral anatomy can be almost anatomically reconstructed by SSA. Solely the humeral head height differs significantly to the preoperative as well as contralateral morphology.

The Walch type B humerus: glenoid retroversion is associated with torsional differences in the humerus

BACKGROUND

The Walch type B glenoid has the hallmark features of retroversion, joint subluxation, and bony erosion. Although the type B glenoid has been well described, the morphology of the corresponding type B humerus is poorly understood. As such, the aim of this imaging-based anthropometric study was to investigate humeral torsion in Walch type B shoulders.

METHODS

Three-dimensional models of the full-length humerus were generated from computed tomography data for the Walch type B group (n = 59) and for a control group of normal nonarthritic shoulders (n = 59). An anatomic humeral head-neck plane was created and used to determine humeral torsion relative to the epicondylar axis. Measurements were repeated, and intraclass correlation coefficients were calculated.

RESULTS

The type B humeri had significantly (P < .001) less retrotorsion (14° ± 9°) than the control group (36° ± 12°) relative to the epicondylar axis. Male and female individuals within the control group showed statistically significant differences in humeral torsion (P = .043), which were not found in the type B group. Inter-rater reliability showed excellent agreement for humeral torsion (intraclass correlation coefficient, 0.962). A subgroup analysis between Walch type B2 and B3 shoulders showed no significant differences in any of the humeral or glenoid parameters.

CONCLUSION

The Walch type B humerus has significantly less retrotorsion than non-osteoarthritic shoulders. At present, it is unknown whether the altered humeral retrotorsion is a cause or effect of the type B glenoid. In addition, it is unknown whether surgeons should be reconstructing type B2 humeral component version to pathologic torsion or to nonpathologic population means to optimize arthroplasty survivorship.

Three-Dimensional Morphometric Modeling Measurements of the Calcaneus in Adults with Stage IIB Posterior Tibial Tendon Dysfunction: A Pilot Study

Background: The pathophysiology of adult-acquired flatfoot deformity (AAFD) is not fully explained by degeneration of the posterior tibial tendon alone. While a shortened or dysplastic lateral column has been implicated in flatfoot deformity in pediatrics, there is no study that has quantified the degree of dysplasia in adults with a stage IIb flatfoot deformity, or if any exists at all. Methods: An institutional radiology database was queried for patients with posterior tibial tendon dysfunction (PTTD) who had computed tomography (CT) performed. Controls were patients receiving CT scan for an intra-articular distal tibia fracture without preexisting foot or calcaneal pathology. Clinical notes, physical examination, and weightbearing radiographs were used to find patients that met clinical criteria for stage IIb PTTD. Morphometric measurements of the calcanei were performed involving the length of the calcaneal axis (LCA), height of the anterior process (HAP), and length of the anterior process (LAP). All measurements were performed independently by separate observers, with observers blinded to group assignment. We considered a difference of ±4 mm as our threshold. Results: 7 patients and 7 controls were available for reconstruction and analysis. On average, the LCA was 3.1 mm shorter in patients with stage IIb PTTD compared with controls (P < .05). The LAP was shorter in PTTD patients compared with controls 3.4 mm (P < .001). Conclusions: Our results support the hypothesis that the calcaneus of adult patients with stage IIb AAFD is dysplastic when compared with healthy controls, which further supports the utility of lateral column lengthening. Levels of Evidence: Level III: Case-control study.

Is global humeral head offset related to intramedullary canal width? A computer tomography morphometric study

Background

While most anatomic TSA stems allow some intra-operative adjustments, the default configuration assumes that head offset is directly proportional to stem diameter. Some authors reported that humeral head diameter is proportional to intra-medullary canal width and humeral head offset, but none investigated the direct relationship between head offset and endosteal measurements. The purpose of the study was to determine whether global humeral head offset is proportional to intramedullary canal width at the distal metaphysis and proximal diaphysis.

Methods

We analyzed 100 Computed Tomography shoulder scans of patients aged 59.1 ± 20.5 with no signs of gleno-humeral arthritis nor humeral dysplasia. The width of the intramedullary diaphyseal canal was determined at four transverse sections 65, 70, 100 and 105 mm below the head center. The inter-observer agreement was excellent for intramedullary canal width (ICC = 0.96), head diameter (ICC = 0.97) and global head offset (ICC = 0.85). Correlations were analysed using Pearson’s coefficients and multivariable regressions were performed to determine associations between head offset and five independent variables (gender, age, intramedullary canal width, head diameter).

Results

Global head offset was negatively correlated with head diameter (r = − 0.31, p = 0.002), but not correlated with intramedullary canal width (r = − 0.11, p = 0.282). Multivariable regression confirmed that global head offset was independently associated with head diameter (beta = − 0.15, p = 0.005), but not with intramedullary canal width (beta = 0.06, p = 0.431).

Conclusions

The present study revealed that humeral offset is not correlated with intramedullary canal width. Implant manufacturers and shoulder surgeons should be aware of the subtle morphologic features, to enhance humeral stem design and restore native anatomy.

A 3D comparison of humeral head retroversion by sex and measurement technique

BACKGROUND

Accurate humeral head reconstruction during shoulder arthroplasty is partially dependent on correctly estimating and replicating native version. The present study evaluated the effects of sex and measurement technique on three-dimensional (3D) humeral version measurements made using the transepicondylar, forearm and flexion-extension axes.

METHODS

Fifty-two full-arm computed tomography scans were converted to 3D models and geometry extracted to define landmarks and coordinate systems. An anatomic humeral head osteotomy plane was used to measure version relative to the three measurement techniques and compare between sexes.

RESULTS

The measurement technique used had a significant affect (p < 0.001) on the resulting version measurement. The forearm axis technique consistently resulted in higher measured version compared to either the flexion-extension [mean (SD) males 9° (4°), females 13° (5°), p < 0.001] or the transepicondylar axes [mean (SD) males 8° (4°), females 11° (4°), p < 0.001]. Version in males was 7° greater than females when referencing either the flexion-extension [p = 0.029; mean (SD) males 37.7° (11°), females 30.4° (13°)] or transepicondylar axes [p = 0.045; mean (SD) males 39° (11°), females 32° (12°)].

CONCLUSIONS

The choice of measurement technique can affect the humeral version angle. These results are important because measuring version using the epicondyles pre-operatively, and subsequently the forearm intra-operatively, will result in approximately 10° under-retroverted osteotomy. For example, 0° neutral version cut during reverse arthroplasty measured referencing the forearm results in 10° anteverted osteotomy when referencing the distal humerus.

Cementless humeral head resurfacing for degenerative glenohumeral osteoarthritis fails at a high rate

Purpose

The aim of the study was to examine clinical and radiographic results of a cementless humeral surface and to evaluate prognostic parameters for implant failure.

Methods

34 shoulders were examined preoperatively and after a mean 2.7 years. Radiographic parameters, Constant scores (CS) and complications were recorded.

Results

The mean CS improved from 27 to 51 points. Eight patients (24%) had an implant revision for secondary glenoid erosion. In the revision group was an increase of the LGHO of 8.4%.

Conclusions

The study shows a high revision-rate (24%). Predictor for an implant failure was an operative changing of the LGHO.

Postoperative Evaluation of Reduction Loss in Proximal Humeral Fractures: A Comparison of Plain Radiographs and Computed Tomography

OBJECTIVE

To compare postoperative CT images with plain radiographs for measuring prognostic factors of reduction loss of fractures of the proximal part of the humerus.

METHODS

A total of 65 patients who sustained fractures of the proximal humerus treated with locking plates from June 2012 to October 2015 were retrospectively analyzed. There were 24 men and 41 women, with a mean age of 60.0 years (range, 22-76 years). According to the Neer classification system of proximal humeral fracture, there were 26 two-part, 27 three-part and 12 four-part fractures of the proximal part of the humerus, and all fractures were treated with open reduction and internal fixation (ORIF) using locked plating. All postoperative CT images and plain radiographs of the patients were obtained. Prognostic factors of the reduction loss were the change of neck shaft angle (NSA) and the change of humeral head height (HHH). The change of NSA and HHH were evaluated by the difference between postoperative initial and final follow-up measurement. Reduction loss was defined as the change ≥10° for NSA or ≥5 mm for HHH. The NSA and HHH were measured using plain radiographs and 3-D CT images, both initially and at final follow-up. The paired t-test was used for comparison of NSA, change of NSA, HHH, and change of HHH between two image modalities. The differences between two image modalities in the assessment of reduction loss were examined using the χ² -test (McNemar test). Intraclass correlation coefficients (ICC) were used to assess the intra-observer and inter-observer reliability.

RESULTS

3-D CT images (ICC range, 0.834-0.967) were more reliable in all parameters when compared with plain radiographs (ICC range, 0.598-0.915). Significant differences were found between the two image modalities in all parameters (plain radiographs: initial NSA = 133.6° ± 3.8°, final NSA = 130.0° ± 1.9°, initial HHH = 17.9 ± 0.9 mm, final HHH = 15.8 ± 1.5 mm; 3-D CT: initial NSA = 131.4° ± 3.4°, final NSA = 128.8° ± 1.7°, initial HHH = 16.8 ± 1.2 mm, final HHH = 14.5 ± 1.1 mm; all P < 0.05). In the assessment of reduction loss, the percentage was 16.9% (11/65) for the plain radiographs and 7.7% (5/65) for the 3-D CT scans (P < 0.05). For the 5 patients with reduction loss, which were observed by two imaging modalities, the mean Constant-Murley score was 61.0 ± 1.6. The patients with reduction loss, observed only in plain radiographs but not CT images, had good shoulder function (Constant-Murley score: 82.7 ± 1.0).

CONCLUSIONS

Our data reveal that 3-D CT images are more reliable than plain radiographs in the assessment of the prognostic factors of reduction loss of fractures of the proximal part of the humerus with treatment of locking plates; this reliable CT technique can serve as an effective guideline for the subsequent clinical management of patients.

Head-shaft angle changes during internal and external shoulder rotations: 2-D angulation in 3-D space

INTRODUCTION

Restoration of native head-shaft angle (HSA) is critical for treatment of proximal humerus fracture. However, HSA has not been properly investigated according to the humeral rotation. This study was designed to analyze the relationship between the humeral rotation and the HSA at 1° increments, and clarify its serial changing pattern according to the humeral rotation.

HYPOTHESIS

The angulation of HSA would be undervalued when the humerus is being rotated externally and it would be overvalued when it is being rotated internally.

MATERIALS AND METHODS

Eight dried cadaveric normal humeri were CT scanned. They were analyzed using computer-aided design with a standardized neutral position. HSA was the angle between the humeral shaft axis (SA) and the humeral head axis (HA). SA and HA were the best-fit lines through center of all the best-fitting circles in every cross section along the humeral shaft and within the humeral head, respectively. Each 3D model was rotated 30° internally and 45° externally relatives to the SA at 1° increments with the camera was fixed at antero-posterior view of neutral position. Angulation of HSA in every rotational degree was documented as ratio relatives to the angulation of HSA in neutral position.

RESULTS

The average HSA at neutral position was 133±1.93°. HSA was underestimated by 8±1.9% and it was overestimated by 20±5.1% at the maximum external rotation (ER) and internal rotation (IR), respectively. HSA was underestimated by 1% in every 5.8° of ER and overestimated by 1% in every 1.5° of IR. Rotational misalignments within 10° of IR and 18° of ER could be tolerated (P>.05).

CONCLUSIONS

HSA was underestimated at ER and was overestimated at IR. This information could be useful for surgeons in restoring the native HSA for treatment of proximal humerus fracture.

TYPE OF STUDY

Basic research study.