Purpose
To establish the accuracy and reliability of the circle-line method (CLM) of measuring
glenoid bone loss; to compare the CLM calculation with a traditionally used method
of calculating a ratio; and to evaluate surgeons' ability to estimate the amount of
glenoid bone loss before performing any calculations.
Methods
Three-dimensional reconstructions of computed tomography scans of consecutive patients
with anterior instability and glenoid bone loss were reviewed by 13 surgeons blinded
to the diagnosis. The reviewers made estimations of bone loss before creating any
measurements by viewing the available computed tomography scan as well as the 3-dimensional
reconstructions. They selected an en face view of the glenoid to create a best-fit
circle. Bone loss calculation with a traditional linear method as well as a CLM calculated
by algebraic geometry was completed. The CLM requires calculation of the diameter
of a best-fit circle on the glenoid, as well as the length of a single line along
the circle representing the line of bone loss. All methods were compared with a computerized
method of tracing the area of the glenoid within a best-fit circle. Interobserver
and intraobserver calculations were performed. Analysis-of-variance testing was used
to compare the estimates of bone loss versus the CLM-calculated bone loss. Tukey post
hoc analysis was used to define the accuracy of the CLM calculation compared with
a more traditional method of calculating bone loss.
Results
Bone loss estimations were significantly different from CLM-calculated bone loss in
all cases except those with greater than 25% bone loss. The CLM was more accurate
in all types of bone loss except cases of greater than 25% bone loss. Interobserver
reliability was very good for the glenoid diameter measurement and moderate for the
CLM. Intraobserver reliability ranged from moderate to good for all methods of measurement.
Conclusions
Surgeon estimations of glenoid bone loss, as well as traditional line-measurement
calculations, are inconsistent and unreliable for accurate determination of the optimal
surgical treatment for anterior shoulder instability. The CLM is a simple, reproducible,
and accurate method for determining glenoid bone loss and does not require specialized
software or imaging protocols.
Level of Evidence
Level II, diagnostic study.
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to ArthroscopyAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- The instability severity index score. A simple pre-operative score to select patients for arthroscopic or open shoulder stabilisation.J Bone Joint Surg Br. 2007; 89: 1470-1477
- What is the critical value of glenoid bone loss at which soft tissue Bankart repair does not restore glenohumeral translation, restricts range of motion, and leads to abnormal humeral head position?.Am J Sports Med. 2016; 44: 2784-2791
- Risk factors for recurrence of shoulder instability after arthroscopic Bankart repair.J Bone Joint Surg Am. 2006; 88: 1755-1763
- Traumatic glenohumeral bone defects and their relationship to failure of arthroscopic Bankart repairs: Significance of the inverted-pear glenoid and the humeral engaging Hill-Sachs lesion.Arthroscopy. 2000; 16: 677-694
- The inverted pear glenoid: An indicator of significant glenoid bone loss.Arthroscopy. 2004; 20: 169-174
- Arthroscopic stabilization for recurrent anterior shoulder dislocation: Results of 59 cases.Arthroscopy. 1995; 11: 173-179
- Recurrent anterior dislocation of the shoulder after surgical repair. Apparent causes of failure and treatment.J Bone Joint Surg Am. 1984; 66: 159-168
- Open operative treatment for anterior shoulder instability: When and why?.J Bone Joint Surg Am. 2005; 87: 419-432
- Treatment of chronic glenoid defects in the setting of recurrent anterior shoulder instability: A systematic review.J Shoulder Elbow Surg. 2010; 19: 769-780
- Management of bone loss associated with recurrent anterior glenohumeral instability.Am J Sports Med. 2005; 33: 912-925
- Treatment of osseous defects associated with anterior shoulder instability.J Shoulder Elbow Surg. 2009; 18: 317-328
- Glenohumeral bone defects in the treatment of anterior shoulder instability.Instr Course Lect. 2009; 58: 323-336
- Effect of an anterior glenoid defect on anterior shoulder stability: A cadaveric study.Am J Sports Med. 2009; 37: 949-954
- Redefining “critical” bone loss in shoulder instability: Functional outcomes worsen with “subcritical” bone loss.Am J Sports Med. 2015; 43: 1719-1725
- Evolving concept of bipolar bone loss and the Hill-Sachs lesion: From “engaging/non-engaging” lesion to “on-track/off-track” lesion.Arthroscopy. 2014; 30: 90-98
- Anterior shoulder dislocation: Quantification of glenoid bone loss with CT.AJR Am J Roentgenol. 2003; 180: 1423-1430
- Assessment of bone defects in anterior shoulder instability.Joints. 2013; 1: 40-48
- 3-D CT is the most reliable imaging modality when quantifying glenoid bone loss.Clin Orthop Relat Res. 2013; 471: 1251-1256
- Area-based determination of bone loss using the glenoid arc angle.Arthroscopy. 2012; 28: 1030-1035
- Assessment and evaluation of glenoid bone loss.Arthrosc Tech. 2016; 5: e947-e951
- Comparison between 2D and 3D computed tomography evaluation of glenoid bone defect in unilateral anterior gleno-humeral instability.Radiol Med. 2012; 117: 102-111
- Comparison of various imaging techniques to quantify glenoid bone loss in shoulder instability.J Shoulder Elbow Surg. 2013; 22: 528-534
- Comparison of 3-dimensional computed tomography-based measurement of glenoid bone loss with arthroscopic defect size estimation in patients with anterior shoulder instability.Arthroscopy. 2015; 31: 1880-1885
Shin SJ, Jun BJ, Koh YW, McGarry MH, Lee TQ. Estimation of anterior glenoid bone loss area using the ratio of bone defect length to the distance from posterior glenoid rim to the centre of the glenoid [published online September 26, 2016]. Knee Surg Sports Traumatol Arthrosc. doi:10.1007/s00167-016-4312-x.
- How to identify and calculate glenoid bone deficit.Chir Organi Mov. 2005; 90: 145-152
- A simple method for quantitative evaluation of the missing area of the anterior glenoid in anterior instability of the glenohumeral joint.Skeletal Radiol. 2008; 37: 731-736
- Recurrent shoulder instability: Current concepts for evaluation and management of glenoid bone loss.J Bone Joint Surg Am. 2010; 92: 133-151
- Glenoid rim morphology in recurrent anterior glenohumeral instability.J Bone Joint Surg Am. 2003; 85: 878-884
- The shape of the inferior part of the glenoid: A cadaveric study.J Shoulder Elbow Surg. 2006; 15: 759-763
- Statistical methods for rates and proportions.Ed 2. John Wiley and Sons, New York1981
- Quantifying glenoid bone loss arthroscopically in shoulder instability.Arthroscopy. 2002; 18: 488-491
- Glenoid diameter is an inaccurate method for percent glenoid bone loss quantification: Analysis and techniques for improved accuracy.Arthroscopy. 2015; 31: 608-614.e1
- Use of preoperative three-dimensional computed tomography to quantify glenoid bone loss in shoulder instability.Arthroscopy. 2008; 24: 376-382
- The effect of sagittal rotation of the glenoid on axial glenoid width and glenoid version in computed tomography scan imaging.J Shoulder Elbow Surg. 2016; 25: 61-68
- Quantifying glenoid bone loss in anterior shoulder instability: Reliability and accuracy of 2-dimensional and 3-dimensional computed tomography measurement techniques.Am J Sports Med. 2012; 40: 2569-2577
- Objective preoperative measurement of anterior glenoid bone loss: A pilot study of a computer-based method using unilateral 3-dimensional computed tomography.Arthroscopy. 2011; 27: 322-329
- A new arthroscopic technique to determine anterior-inferior glenoid bone loss: Validation of the secant chord theory in a cadaveric model.Arthroscopy. 2009; 25: 1249-1256
- Measurement of glenoid bone loss: A comparison of measurement error between 45 degrees and 0 degrees bone loss models and with different posterior arthroscopy portal locations.Am J Sports Med. 2008; 36: 1132-1138
Article info
Publication history
Published online: October 21, 2017
Accepted:
July 27,
2017
Received:
January 17,
2017
Footnotes
The authors report the following potential conflict of interest or source of funding: M.T.P. receives support from AOSSMA/AANA, Arthrex/JRF, PRORP shoulder instability database. Arthrex. Suture washer and pec button. Elsevier–Arthroscopy Journal, Shoulder Instability Textbook, Rehabilitation Textbook. Full ICMJE author disclosure forms are available for this article online, as supplementary material.
Identification
Copyright
Published by Elsevier on behalf of the Arthroscopy Association of North America
