Orthopedics

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Feature Article 

Changes in Bone Mineral Density of the Proximal Humerus in Koreans: Suture Anchor in Rotator Cuff Repair

Jin-Young Park, MD, PhD; Myung-Ho Kim, MD, PhD

Abstract

abstract

This study was conducted to obtain data concerning suture failure by identifying the change in bone mineral density in the proximal humerus relative to age and gender. Bone mineral density of the greater tuberosity, humeral head, and surgical neck of the proximal humerus was measured in 175 individuals (74 men and 101 women) aged >40 years. Compared to individuals in their 40s, the bone mineral density of the greater tuberosity of the humerus for women in their 70s showed a 42% decrease and in men a 43% decrease. It is therefore recommended that cadavers used for subsequent research on the fixation strength of suture anchors undergo bone mineral density analysis.

Abstract

abstract

This study was conducted to obtain data concerning suture failure by identifying the change in bone mineral density in the proximal humerus relative to age and gender. Bone mineral density of the greater tuberosity, humeral head, and surgical neck of the proximal humerus was measured in 175 individuals (74 men and 101 women) aged >40 years. Compared to individuals in their 40s, the bone mineral density of the greater tuberosity of the humerus for women in their 70s showed a 42% decrease and in men a 43% decrease. It is therefore recommended that cadavers used for subsequent research on the fixation strength of suture anchors undergo bone mineral density analysis.

Suture anchors, which are used to fix the tendon or ligament to the bone, are on the rise as shoulder arthroscopy is widespread.1,2 However, suture anchors can cause complications such as anchor failure due to pull-out or improper placement, and suture failure due to tension and degree of strength.* According to previous reports, bone mineral density of the proximal humerus did not influence suture anchor pull-out strength.4"*' However, recent reports claim that fixation capability of screw-type suture anchors decreases according to the decrease in bone mineral density.7 In addition, one report demonstrated that a suture anchor, which was input in the proximal humerus, caused failure.8

This study identified changes incurred in the bone mineral density of the proximal humerus relative to age and provides basic data for research that aims to identify the causes of suture failure in relation to the decrease of bone mineral density of the proximal humerus.

MATERIALS AND METHODS

Bone ratinerai density was measured in 175 individuals (74 men and 101 women) aged >40 years using dual-energy x-ray absorptiometry (Norland XR-26 MARK; Norland Scientific Instruments, Fort Atkinson, Wis) in the lumbar spine and greater tuberosity, head, and surgical neck of the proximal humerus. Measurements were obtained during an annual examination of public health care insurance with permission from the ethic and financial committees of the hospital. Individuals who had diseases that could lead to osteoporosis such as diabetes mellitus, Cushing's syndrome, parathyroid hormone and thyroid hormone disorders, alcoholism, rheumatoid arthritis, chronic liver disease, connective tissue disorder, and metabolic bone disease were excluded, as well as those who had a history of shoulder disease. Individuals who experienced immobilization or underwent surgery on the target shoulder and those with pain and tenderness and limitation of motion or daily living activities also were excluded.8

Average age was 53 years (range: 4087 years) and 59 years (range: 40-91 years), average height was 167 cm (range: 153-180 cm) and 154 cm (range: 140-170 cm), and average weight was 66 kg (range: 41-94 kg) and 57 kg (range: 36-80 kg) for men and women, respectively (Table 1). The height and weight of the study participants were compared with Koreans who acted as controls (Table 2).

Bone mineral density in the anteroposterior view of the second to fourth lumbar spine was measured to compare the average value of the participants (Table 1 ) with the average value of control Koreans (Table 3). As for bone mineral density of the proximal humerus, the elbow underwent 90° flexion followed by 30° external rotation to measure the same section. The three sections - the humeral head, greater tuberosity, and surgical neck - were measured (Figure 1 ).

Table

TABLE 1Demographic Findings

TABLE 1

Demographic Findings

RESULTS

The average bone mineral density from the second to fourth lumbar spine was 0.89 gm/cm2 for women and 1.07 gm/cm2 for men. Bone mineral density of the lumbar spine of the male participants manifested higher bone mineral density than the average value of the controls at each decade (Tables 1 and 3). However, decreases occurred (Figure 2). Although bone mineral density of the female participants' lumbar spine manifested lower bone mineral density than the average value of the controls at each decade, decreases also occurred (Figure 2). The highest correlation between bone mineral density of the study participants* lumbar spine and bone mineral density of the proximal humerus was found in the humeral head (r=0.55 for men and r=0.58 for women) (Table 4).

Table

TABLE 2Average Height and Weight of Koreans Who Visited the General Health Screening Center of Dankook University Hospital Between lanuarv 2002 and December 2002

TABLE 2

Average Height and Weight of Koreans Who Visited the General Health Screening Center of Dankook University Hospital Between lanuarv 2002 and December 2002

Figure 1: Bone mineral density on the proximal humerus was measured using DXA. Boundary is set in squares to conduct two-dimensional measurement of bone mineral density for the humeral head, greater tuberosity, and surgical neck.

Figure 1: Bone mineral density on the proximal humerus was measured using DXA. Boundary is set in squares to conduct two-dimensional measurement of bone mineral density for the humeral head, greater tuberosity, and surgical neck.

Average bone mineral density was 0.63 g/cm2 and 0.91 g/cm2 at the greater tuberosity, 0.87 g/cm2 and 1.18 g/cm2 at the humeral head, and 0.54 g/cm2 and 0.87 g/cm2 at die surgical neck for women and men, respectively. The bone mineral density of the proximal humerus was lower in women. Humeral head bone mineral density was the highest in both men and women, followed by the greater tuberosity and surgical neck (Table 1).

Figure 2: Comparison of the bone mineral density between the spine and proximal humerus according to age in women (A) and men (B).

Figure 2: Comparison of the bone mineral density between the spine and proximal humerus according to age in women (A) and men (B).

All individuals showed a decrease in the greater tuberosity, humeral head, and surgical neck bone mineral density with increasing age. Compared to the controls in their 40s, women in their 70s showed a 42%, 35%, and 54% decrease in bone mineral density of the greater tuberosity, humeral head, and surgical neck, respectively, whereas men showed a 43%, 35%, and 22% decrease, respectively (Table 1 ).

DISCUSSION

The bone tunnel technique developed by McLaughlin9 for rotator cuff tear repair has become the classic method. Although controversy surrounds the best method for rotator cuff repair,610'12 suture anchor use has recently increased due to the small incision, easy repair, low postoperative morbidity, and reduction of operative time. However, surgical failure due to suture anchor failure can result from insufficient fixation capability of the metal suture anchor or improper anchor insertion.3

During in vitro repair of the rotator cuff using a suture anchor. Craft et al13 reported that the ultimate failure strength was affected by the viscoelastic behavior of the soft tissue, axis of pull, quality of torn tendon, and bone density. Among these, the results of rotator cuff repair deteriorate with decreasing bone mineral density, and various methods have been attempted to increase the fixation capability.50

Table

TABLE 3Average Bone Mineral Density (g/cm2) of Koreans From the Second to Fourth Lumbar Spine*

TABLE 3

Average Bone Mineral Density (g/cm2) of Koreans From the Second to Fourth Lumbar Spine*

Table

TABLE 4Correlation Coefficients Between Bone Mineral Density of the Lumbar Spine and Proximal Humerus

TABLE 4

Correlation Coefficients Between Bone Mineral Density of the Lumbar Spine and Proximal Humerus

During arthroscopic rotator cuff repair, the authors use the traction suture by exerting sufficient release of the torn cuff to the greater tuberosity. The suture anchor is used to execute arthroscopic repair without tension to the torn rotator cuff; however, the authors experienced pull-out failure and deadman angle1415 failure. Pull-out failure occurred during the arthroscopic repair of a bursal partialthickness rotator cuff tear in a 62- year-old man who had continual shoulder pain of 7 years' duration. The suture anchor that caused pull-out failure was the 5.2-mm cancellous Statak screw (Zimmer, Warsaw, lnd).

Another type of suture anchor failure experienced by the authors was medial displacement of the suture and cortical breakage at die greater tuberosity of the humerus. Failure occurred when significant tension was applied to the stitch to suture the torn rotator cuff on the bony insertion of die greater tuberosity (Figure 3). The authors designate this phenomenon as deadman angle failure, which may be a prodromal stage of pull-out anchor failure.

Figure 3: Deadman angle failure occurred during arthroscopic rotator cuff repair due to high tension applied to the suture. The solid line indicates the location where the suture anchor was inserted initially and the dotted line shows how the suture anchor moved inward with cortical breakage after the suture tie (Fastin RC anchor; Mitek, Westwood, Mass).

Figure 3: Deadman angle failure occurred during arthroscopic rotator cuff repair due to high tension applied to the suture. The solid line indicates the location where the suture anchor was inserted initially and the dotted line shows how the suture anchor moved inward with cortical breakage after the suture tie (Fastin RC anchor; Mitek, Westwood, Mass).

A 71 -year-old woman with shoulder pain of 1 year's duration underwent arthroscopic repair for a medium-sized rotator cuff tear. Medical history was significant for hemiparesis due to cerebral infarct 5 years prior to presentation. Average anteroposterior bone mineral density from die second to fourth lumbar spine was 0.779 g/cm2 (t score=-2.23). Bone mineral density of the greater tuberosity was 0.276 g/cm2, the surgical neck 0.400 g/cm2, and the humeral head 0.326 g/cm2. Two Fastin RC anchors (Mitek, Westwood, Mass) were inserted to perform four tendon-tobone repairs. Deadman angle failure occurred while performing the repair using die SMC sliding knot16 after insertion of die first anchor on die greater tuberosity.

The authors believe these suture anchor failures resulted due to die suture anchor's low fixation capability and the decrease in the patient's bone mineral density. Thus, the authors intend to provide data for research of bone anchors by measuring how bone mineral density changes in relation to age and gender.

Until recentiy, porcine femur17,18 and human cadaver tibiae and humerus512 were used to research die fixation capability of suture anchors. Because of this research, relative comparison of fixation capability was possible. However, as bone mineral density and bony structure of the proximal humerus differ from that of die femur and tibia, direct application of die fixation capability to the greater tuberosity of patients with rotator cuff tear is difficult.

According to Rossouw et al1 ' and Craft et al,13 who used the human cadaveric shoulder model, suture failure occurred due to bone failure; however, the goal of dieir research was to minimize anchor pull-out. In a humeral greater tuberosity with osteopenia, 3.2-mm Harpoon (Biomet Inc. Warsaw, Ind) and 4.0-mm Revo screw (Linvatec Corp, Largo. FIa) generated failure more than other anchors such as the 3.2-mm Superanchor (Mitek Surgical Products Ine, Norwood, Mass) and Statak screw (Zimmer).13

As a result of this study, it was possible to observe that the bone mineral density of each part of the proximal humerus decreased considerably as age increased. Furthermore, women showed lower bone mineral density than men. Among the current research on the fixation capability of suture anchors, studies regarding the proximal humerus used cadavers of different ages and gender.7,13 In the study by Craft et al,13 human cadavers with an average age of 69 years (range: 46-80 years) were used and it was impossible to determine what degree of osteopenia could result in bone failure. Use of cadavers with different bone mineral density levels seems unsuitable for the prediction of consistent results.

As reported by Craft et al,13 Leppala et al,19 and Okamura and Ozaki,20 when shoulder disease is present, bone mineral density is decreased. Thus, when women of advanced ages manifest chronic rotator cuff tear, it is believed that suture anchor failure can occur more easily.

CONCLUSION

Older individuals and women had relatively lower bone mineral density of the proximal humerus. Thus, during rotator cuff repair using a suture anchor, the possibility of suture failure is increased in diese groups. It is therefore recommended that cadavers used for subsequent research on the fixation capability of suture anchors undergo bone mineral density analysis.

REFERENCES

1. Snyder S. Arthroscopic evaluation and treatment of die rotator cuff. In: Snyder S, ed. Shoulder Arthroscopy. New York. NY: McGraw-Hill; 1994:161-166.

2. Ttramerman L, Andrews J, WiIk K. Miniopen repair of die rotator cuff. I: Andrews J, WiIk K, eds. In: The Athlete's Shoulder. New York, NY: Churchill Livingstone; 1994:153163.

3. Kaar TK. Schenck RC Jr, Wirth MA, Rockwood CA Jr. Complications of metallic suture anchors in shoulder surgery: a report of 8 cases. Arthroscopy. 2001: 17:31-37.

4. Barber FA, Feder SM. Burkhart SS, Ahrerts J. The relationship of suture anchor failure and bone density to proximal humerus location: a cadaveric study. Arthroscopy. 1997; 13:340-345.

5. Goradia VK. Mullen DJ, Boucher HR, Parks BG. O'Donnell JB. Cyclic loading of rotator cuff repairs: A comparison of bioabsorbable tacks with metal suture anchors and transosseous sutures. Arthroscopy. 2001 : 17:360-364.

6. Reed SC. GIossop N, Ogilvie-Harris DJ. Fullthickness rotator cuff tears. A biomechanical comparison of suture versus bone anchor techniques. Am J Sports Med. 1996; 24:46-48.

7. Stanford RE, Harrison J, Goldberg J, Sonnabend DH, Alvis M, Walsh WR. A novel, resorbable suture anchor pull-out strength from the human cadaver greater tuberosity. J Shoulder Elbow Surg. 2001: 10:286-291.

8. Marchetti ME. Houde JP, Steinberg GG, Crane GK. Goss TP, Baran DT. Humeral bone density losses after shoulder surgery and immobilization. J Shoulder Elbow Surg. 1996;5:471-476.

9. McLaughlin HL. Lesions of the musculotendinous cuff of the shoulder. The exposure and treatment of tears with retraction. J Bone Joint Surg Am. 1944: 26:31-49.

10. Gerber C. Schneeberger AG, Beck M, Schlegel U. Mechanical strengdj of repairs of the rotator cuff. J Bone Joint Surg Br. 1994: 76:371-380.

11. Rossouw DJ, McElroy BJ, Amis AA, Emery RJ. A biomechanical evaluation of suture anchors in repair of the rotator cuff. J Bone Joint Surg Br. 1997; 79:458-461.

12. Sward L, Hughes JS, Amis A, Wallace WA. The strength of surgical repairs of the rotator cuff. A biomechanical study on cadavers. J Bone Joint Surg Br. 1992; 74:585-588.

13. Craft DV, Moseley JB, Cawley PW. Noble PC. Fixation strength of rotator cuff repairs with suture anchors and the transosseous suture technique. J Shoulder Elbow Surg. 1996; 5:32-40.

14. Burkhart SS. The deadman theory of suture anchors: observations along a south Texas fence line. Arthroscopy. 1995; 11:1 19-123.

15. Burkhart SS. "Deadman theory," Orthopedics. 2003; 26:124,131.

16. Kim SH, Ha Kl. The SMC knot- a new slip knot with locking mechanism. Arthroscopy. 2000; 16:563-565.

17. Barber FA, Herbert MA, Click JN. Suture anchor strength revisited. Arthroscopy. 1996; 12:32-38.

18. France EP. Paulos LE, Harner CD, Straight CB. Biomechanical evaluation of rotator cuff fixation methods. Am J Sports Med. 1989: 17:176-181.

19. Leppala J, Kannus P, Sievanen H, Jarvinen M, Vuori I. Adhesive capsulitis of the shoulder (frozen shoulder) produces bone loss in the affected humerus, but long-term bony recovery is good. Bone. 1998; 22:691-694.

20. Okamura K, Ozaki J. Bone mineral density of the shoulder joint in frozen shoulder. Arch Orthop Trauma Surg. 1999; 1 19:363-367.

TABLE 1

Demographic Findings

TABLE 2

Average Height and Weight of Koreans Who Visited the General Health Screening Center of Dankook University Hospital Between lanuarv 2002 and December 2002

TABLE 3

Average Bone Mineral Density (g/cm2) of Koreans From the Second to Fourth Lumbar Spine*

TABLE 4

Correlation Coefficients Between Bone Mineral Density of the Lumbar Spine and Proximal Humerus

10.3928/0147-7447-20040801-22

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