Correlation of Antero-inferior Glenoid Bone Loss with Number of Dislocations and Mode

of Injury

Aravindh Palaniswamy, MS1 , Hira Lal Nag, MS1 , Dhanasekaraprabu, MS1 , Deep N Srivastava, MD2

Department of Orthopaedics1 & Radiodiagnosis2,All India Institute of Medical Sciences, New Delhi, India

Introduction

• Recurrent shoulder dislocation is a common cause of

morbidity among young adults with an annual incidence of

0.084% & 1.7%(1) .

• Natural history of the unstable shoulder evolves towards

progressive glenoid bone loss.

• Incidence as high as 86%(2) in recurrent instability.

1.Hovelius L. Incidence of shoulder dislocation in Sweden. Clin Orthop Relat Res 982:127-131.2.Griffith JF, Antonio GE, Yung PSH, Wong EMC, Yu AB, Ahuja AT, et al. Prevalence, Pattern, and Spectrum of Glenoid Bone Loss in Anterior Shoulder Dislocation: CT Analysis of 218 Patients. Am. J. Roentgenol. 2008 May;190(5):1247–54.

Introduction

• The integrity of the osseous architecture of the glenoid has

been highlighted as one of the most important factors related

to the success/failure of surgical repair(3,4).

3.Randelli P, Ragone V, Carminati S, Cabitza P. Risk factors for recurrence after Bankart repair a systematic review. Knee Surg. Sports Traumatol.Arthrosc. 2012 Jul 27;20(11):2129–38. 4.ITOI E, LEE S-B, BERGLUND LJ, BERGE LL, AN K-N. The Effect of a Glenoid Defect on Anteroinferior Stability of the Shoulder After Bankart Repair: A Cadaveric Study*. J. Bone Jt. Surg. 2000;82(1):35–46.

Introduction

• Three-dimensional reformatted computed tomography scan

images provides most accurate assessment of bone

deficiency(6).

6.MOON Shoulder Group, Bishop JY, Jones GL, Rerko MA, Donaldson C. 3-D CT is theMost Reliable Imaging Modality When Quantifying Glenoid Bone Loss. Clin.Orthop.Relat. Res. 2012 Sep 21;471(4):1251–6.

Introduction

• Glenoid bone loss – multifactorial origin(5)

– Increasing number of dislocations

– Trauma at first dislocation

– Age of first dislocation

• Considered as strong predictors for the presence and the

percentage of glenoid bone defect

5.Provencher CMT. Recurrent Shoulder Instability: Current Concepts for Evaluation andManagement of Glenoid Bone Loss. J. Bone Jt. Surg. Am. 2010 Dec 1;92(Supplement_2):133.

Study Rationale – Pre-Op CT ?

• Is it Specific findings in the history and the physical

examination provide important clues to the presence of

glenoid bone loss.

• Is it critical to evaluate all patients with recurrent shoulder

instability for the presence of osseous injuries to the glenoid.

Objectives

• To correlate the percentage of glenoid bone loss with ‘number

of dislocations’.

• To asses the influence of ‘mode of injury’ on glenoid bone loss

in patients with recurrent anterior dislocation of shoulder.

Methodology

• Type of study

– Observational Study

• Sample size

– 20 patients

• Approved by Institutional ethics committee

• Informed consent obtained

Methodology

Inclusion criteria

• Patients with recurrent

anterior shoulder

dislocation

• Unilateral involvement

• Age 15 to 45 years

Exclusion criteria

• Habitual dislocation

• H/o previous surgery for

shoulder dislocation

• Any associated congenital

anomaly

Patient Evaluation

• A detailed clinical history

– Mode of injury (Trauma/Sports Injury) which led to dislocation

– Frequency of dislocations were noted

• Physical examination for anterior apprehension & s/o

laxity

Patient Evaluation

• CT Protocol & Image Analysis

– Simultaneous CT examination of both shoulders were

acquired in MDCT scanners (Somatom sensation, Siemens,

Erlanger, Germany) with a volume data acquisition of 0.6 X

40, slice thickness of 0.6 mm with the scanning plane

extending from the acromion to just below glenoid.

Patient Evaluation

– 3D volume rendered

images were

reconstructed

– ‘En face view of

glenoid’ obtained

after subtracting

humeral head.

Patient Evaluation

• Calculation of glenoid index

– On en face view of glenoid of 3 D volume rendered image with use of built in software tools of Siemens Syngo.

– A line drawn along the long axis of glenoid & second glenoid line drawn perpendicular to the long axis of glenoid at the inferior glenoid from the posterior margin to the anterior margin

Patient Evaluation

• Calculation of glenoid bone loss

– Width of the glenoid (glenoid index) in millimetres

calculated on affected(d) and normal shoulder(D)

– Based on the glenoid linear defect method percentage of

bone loss was calculated using the formula

[ (D-d)/D] x 100

• Statistical analysis performed with statistical software (SPSS

version 19)

Results

• Mean age 26.5 ±5.9 years (range 20 to 42 years)

• Male: Female ratio 19:1

• 70% of patients (n=14) had dislocation of right shoulder

• Glenoid bone loss present in 90% (n=18) patients

• 10 patients had ≤ 10% glenoid bone loss, 5 patients between 10 and 20%, 2 between 20 and 30% while 1 patient had >30% bone loss

• Sports injury was the predominant mode of injury in 55% of patients (n=11) while trauma was implicated in rest of the patients

• No. of recurrent dislocations varied from 2 to 20 with a mean of 7.7 (± 5.7)

No. of dislocations and glenoid bone loss (%) in individual study patients

0

5

10

15

20

25

30

35

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Study patients

NO. OF DISLOCATIONS GLENOID BONE LOSS (%)

Correlation between glenoid bone loss and no. of dislocations

Spearman's rho = 0.358p=0.12

Glenoid bone loss in patients with sports injury and trauma

0

2

4

6

8

10

12

14

Sports Injury Trauma

7.2

13.7

Gle

no

idb

on

e lo

ss (

%)

Mode of Injury

(p=0.053)

7.2 (± 9.1) 13.7 (± 7.4)

Discussion

• Anteroinferior glenoid bone loss present in 90% of patients.

• Frequency of dislocations less important in determining bone

loss(p=0.12)

• One patient with 20 episodes of dislocations had 0% of bone

loss with glenoid width measuring of 25mm and another

patient with only 5 episodes of dislocation had 24.6% of bone

loss with a glenoid width of 17.6mm

• Initial mode of injury may appear to influence the defect

(p=0.053).

Discussion

• Milano et al (7)

– Initial mode of injury or the severity of trauma of the first few

episodes and age at first dislocation are significant predictors of

glenoid bone loss in anterior shoulder instability.

– Even though frequency of dislocations correlated with percentage of

bone loss in their study, it was largely influenced by other

confounding factors such as ‘force sustained in the initial trauma’, the

duration of the disease .

Discussion

• Griffith et al(2)

– Clear relationship between traumatic mode of injury in the initial episode of dislocation & percentage of bony bankart.

– Inverse Exponential relationship was found between the degree of anterior flattening and the number of dislocations.

– First few dislocations had a greater effect on the percentage of bone loss.

Discussion

• Yong Girl Rhee et al(8)

– Age, activity, frequency and interval of dislocation have close

relationships with the redislocation rates.

– But presence of bony Bankart lesions are unrelated to the

redislocation rates.

– It is possible that type of Bankart lesion & severity of bony Bankart

lesions are determined at first dislocation.

Conclusion

• Frequency of dislocations appeared to less important in

determining the amount of glenoid bone loss

• Initial mode of injury causing the first episode of anterior

shoulder dislocation may appear to influence the defect

Study Limitation

• Small sample size

Clinical Relevance

Adequate imaging with 3D CT should be included in routine

preoperative evaluation in patients with recurrent anterior

shoulder instability to avoid any unpleasant surprises intra

operatively

Thank you