Shoulder Separation – OrthoInfo – AAOS

Diseases & Conditions

Shoulder Separation

A shoulder separation is not truly an injury to the shoulder joint. The injury actually involves the acromioclavicular joint (also called the AC joint). The AC joint is where the collarbone (clavicle) meets the highest point of the shoulder blade (acromion).

Illustration shows the normal bony anatomy of the shoulder area. The red arrow points to the joint that comes apart in a shoulder separation injury.  

The most common cause for a separation of the AC joint is from a fall directly onto the shoulder. The fall injures the ligaments that surround and stabilize the AC joint.

This figure shows the intact ligaments around the acromioclavicular joint, or AC joint. The red arrow points to the ligaments that are around the joint itself, called the AC ligaments. 

If the force is severe enough, the ligaments attaching to the underside of the clavicle are torn. This causes the separation of the collarbone and the shoulder blade. The shoulder blade (scapula) moves downward from the weight of the arm, creating a bump or bulge above the shoulder.

The injury can range from a mild sprain without a bump to a complete disruption with a very large bump. Good pain-free function often returns even with a very large bump. 

• A mild shoulder separation involves a sprain of the AC ligaments that does not move the collarbone and looks normal on X-rays.
• A more serious injury tears the AC ligaments and sprains or slightly tears the coracoclavicular (CC) ligament, putting the collarbone out of alignment to some extent with a smaller bump.
• The most severe shoulder separation completely tears both the AC and CC ligaments and puts the AC joint noticeably out of position, with a larger bump.

The three grades of shoulder separation

The injury is easy to identify when it causes deformity.

When there is less deformity, the location of pain and X-rays help the doctor make the diagnosis. Sometimes having the patient hold a weight in the hand can increase the deformity, which makes the injury more obvious on X-rays.

Nonsurgical Treatment

Nonsurgical treatments, such as a sling, cold packs, and medications can effectively help manage the pain in almost all patients. Rarely, a doctor may use more complicated supports to help lessen AC joint motion and pain.

Most people with this injury — even professional athletes — return to normal function with nonsurgical treatments, even if there is a persistent, significant deformity/bump. Some people have continued pain around the AC joint, even with only a mild deformity. This may be due to:

• Abnormal contact between the bone ends when the joint is in motion
• Development of arthritis
• Injury to the cartilage between the clavicle and acromion

It is often worthwhile to wait and see if reasonable function returns without surgical treatment.  Most patients, even with very severe injuries, are often managed effectively without surgery. In fact, recent studies on AC joint injuries have shown that nonsurgical management may be better than surgical management in most types of AC joint injuries.

Surgical Treatment

Surgery can be considered if pain persists or the deformity is severe. A surgeon might recommend trimming back the end of the collarbone so it does not rub against the shoulder blade bone (acromion).

When there is significant deformity, reconstructing the ligaments that attach to the underside of the collarbone is helpful. This type of surgery works well even if it is done long after the problem started.  These operations can be done arthroscopically or open, with a plate or without. If a plate is used to assist with the surgery, it is usually removed after healing of the shoulder separation.

Whether treated nonsurgically or with surgery, the shoulder will require rehabilitation to restore and rebuild motion, strength, and flexibility.

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Last Reviewed

April 2022

Contributed and/or Updated by

George S. Athwal, MD

Peer-Reviewed by

Stuart J. Fischer, MDThomas Ward Throckmorton, MD, FAAOS

AAOS does not endorse any treatments, procedures, products, or physicians referenced herein. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific orthopaedic advice or assistance should consult his or her orthopaedic surgeon, or locate one in your area through the AAOS Find an Orthopaedist program on this website.

Acromioclavicular Joint Separation – Undergraduate Diagnostic Imaging Fundamentals

Case

Acromioclavicular joint dislocation

Clinical:

History – 21 year old female injured her shoulder while wrestling.

Symptoms – This patient complained of a deformed, painful, end of her right collar bone.

Physical – There was swelling and tenderness of the region of the acromioclavicular joint.

DDx:

Acromioclavicular Joint Separation

Clavicle Fracture

Acromion Fracture

Hematoma

Imaging Recommendation

ACR – MSK – Acute Shoulder Pain, Variant 1

Shoulder X-ray

ODIN Link to AC Joint Separation images, Figure 14.2A and B: https://mistr.usask.ca/odin/?caseID=20150209202015857

Figure 14.2A X-ray of the right shoulder, Y-view, with AC joint separation
Figure 14.2B X-ray of the right shoulder, AP, with AC joint separation

Imaging Assessment

Findings:

The lateral clavicle was displaced cranially and the acromioclavicular joint was widened.  The coracoclavicular distance was also widened.

Interpretation:

Acromioclavicular joint dislocation, Type 3.

Diagnosis:

Acromioclavicular joint dislocation

Discussion:

Acromioclavicular joint injuries can be graded on the 6-point Rockwood scale:

Figure 14. 3 Acromioclavicular injury classification

X-ray findings may include:

• Minor injuries of this joint space usually involve only the joint capsule and the acromioclavicular ligament.
• With more severe injuries the coracoclavicular ligament may be torn leading to a more displaced clavicle and a wider coracoclavicular distance.
• Severe injuries can involve the coracoclavicular ligament, the deltoid muscle and the trapezius muscle.

Figure 14.2A X-ray of the right shoulder with AC joint separation by Dr. Brent Burbridge MD, FRCPC, University Medical Imaging Consultants, College of Medicine, University of Saskatchewan is used under a CC-BY-NC-SA 4.0 license.

Figure 14.2B X-ray of the right shoulder with AC joint separation by Dr. Brent Burbridge MD, FRCPC, University Medical Imaging Consultants, College of Medicine, University of Saskatchewan is used under a CC-BY-NC-SA 4.0 license.

Figure 14.3 Acromioclavicular injury classification. Courtesy of Dr. Roberto Schubert, Radiopaedia.org, RID: 19124. Originally published at https://radiopaedia.org/cases/rockwood-classification-system-of-acromioclavicular-joint-injuries under a Creative Commons Attribution-Non-commercial-Share Alike 3.0 License.

Physiotherapy SMT

Physiotherapy SMT is a method based on the properties of sinusoidal modulated currents.

Amplipulse therapy (SMT) is a domestic method of treatment with electricity, in which alternating currents act in the form of amplitude pulsations. Sinusoidal modulated currents activate blood supply and reduce venous congestion, ischemia and swelling of tissues, stimulate metabolic processes in organs and tissues, even deeply located. Currents directly affect the nerve endings and muscles. Procedures have an analgesic effect. The duration of anesthesia is due to the fact that morphine-like peptides are released into the central nervous system. Exposure to sinusoidal modulated currents stimulates fat metabolism in the body.

Indications for the use of SMT physiotherapy

• – diseases of the peripheral nervous system – neuralgia, neuropathy, radiculitis, etc.;
• – diseases and injuries of the joints and the musculoskeletal system;
• – pulmonology – bronchitis and bronchial asthma, pneumonia;
• – diseases of the gastrointestinal tract – stomach ulcers, gastritis, indigestion and constipation, biliary dyskinesia;
• – urology – cystitis and pyelonephritis, prostatitis and impotence, enuresis, ureteral stones;
• – heart disease – hypertension I, II degree, migraine, circulatory failure of the brain and spinal cord, atherosclerosis of the vessels of the extremities, etc.;
• – inflammatory and degenerative eye diseases;
• – ENT diseases – vasomotor rhinitis, pharyngitis;
• – diseases of the nervous system – cerebral strokes, cerebral palsy;
• – this method of therapy is quite effective for uterine myoma, endometriosis, mastopathy in subacute stages.

The use of sinusoidal modulated currents is contraindicated:

• – in acute inflammatory processes and purulent processes;
• – with malignant tumors and suspicions of them;
• – in the active form of pulmonary tuberculosis;
• – at high body temperature;
• – when the patient has disorders of the blood coagulation function;
• – in the presence of fresh hematomas on the tissues and in the joint cavity;
• – with ruptures of muscles and ligaments;
• – with thrombophlebitis at the site of exposure;
• – pregnancy;
• – Contraindications to sinusoidal modulated currents also include the presence of a pacemaker, because it can fail under the influence of vibrations.

Positive qualities of SMT physiotherapy:

• – a persistent and tangible effect that is observed almost immediately. This is because the amplitude pulsation of the alternating current directly affects the nerve endings;
• – security. The current potential is as close as possible to the biological indicator of electricity in the human body. Therefore, SMT therapy is the most gentle method of treatment recommended even for children;
• – no side effects. If the doctor prescribes you treatment with sinusoidally modulated currents, you should not be afraid of negative consequences – and this is important.

It is important to remember that amplipulse therapy is a method, although considered safe, but using electric current. And this means that you should trust your health only to knowledgeable specialists working on modern equipment.

One session of SMT therapy lasts from 10 minutes to 1 hour. The doctor decides on the time of exposure based on the diagnosis of the patient. Usually the course of procedures consists of 7-10 daily sessions.

<< Back to the “Treatment” page of the Podlipki sanatorium

Vector drawing machine No. 3 / Habr

As an engineer, I have always been impressed by the Russian pragmatic manner of naming new products. If some Western marketer can name a small CRT-based gaming device “The Vectormatic Score-Master 3000”, then Russians tend to use more meaningful names. And since a third attempt at creating a vector rendering system is being considered, they would call it Vector Drawing Machine #3. Account engineers – marketers (15: 0).

Years ago, I was fascinated by the idea of ​​using a small oscilloscope cathode ray tube to display an analog clock. This undertaking, of course, promised aesthetic pleasure, but at the same time it seemed ridiculous. The idea of ​​replacing the chain of mechanical links with a microcontroller driving two high-voltage differential amplifiers and an independent high-voltage power supply just to roughly tell the time seemed a bit silly.
If, at the same time, we take into account all the work on the implementation of each stage of the process, which should result in a decent-looking device, and add a detailed design study, then the whole project already hinted at its monumentality.

None of the many proposed tasks was particularly difficult in itself, but taken as a whole, it is the stage of integrating everything together in such projects that reveals the complexities of the interconnections of individual components.

This article is about assembling a simple CRT-based space game. This project describes the architecture, provides design notes, comments on the equipment used, electronics, implementation of high voltage power, and the process of laser cutting the case.

General

The body is assembled from two main parts, made of MDF board using laser cutting. The upper part houses the CRT display, high voltage power supply, deflection channels and the corresponding calibrators. At the bottom there is a joystick, buttons, a microcontroller and a low voltage power supply. At the back there is a power connector and a USB mini B socket. The upper segment of the case is put on the lower one, and the whole structure is fixed by a flat control panel with a joystick and buttons.

CRT

The CRT used is the D7-16G, which is just over 76mm in diameter, 160mm long and is battery powered. I bought three of these CRTs many years ago for just such projects.

CRT D7-16G

It uses a 11-pin 30-232 type connector, which is very difficult to find. After some thought, I had the idea to build my own by laser-cutting a blank from a sheet of acrylic and selecting the appropriate contact pins from the base of the lamp panel.

Connector Assembly 30-232

To do this, I designed two stacked blanks in Autocketch so that the CRT contacts are located along the “D” contour of the left part. Each piece was then cut from 3mm acrylic sheet and glued together. I removed the contacts from the new B9A lamp panel, inserted them into a glued blank and slightly bent them to fix them, then soldered the wires to their terminals, insulating the connections with heat shrink.

High voltage power supply

This unit is based on an SG3525 switching regulator driving a push-pull N-FET stage, accompanied by a small ferrite transformer with high and low voltage secondary coils. The high voltage side passes through the positive half-wave rectifier, generating about 240V DC, after which it is reduced by a parallel regulator to 210V. The rectified voltage is applied to the deflection amplifiers and consumes about 7mA. The HV secondary voltage is also doubled, generating approximately -600V, 1mA, to bias the electron gun beam. Balancing any DC secondary current that can saturate the core or cause its magnetic displacement is realized by positive and negative rectifiers.

The structure of the transformer starts with a primary winding in the middle, after which there is a grounded beginning of the secondary winding HV, ending with an anode voltage terminal. Finally, there is a low voltage winding, which is used to heat the coil of the cathode ray tube. This order is chosen to avoid breakdown between the high and low voltage windings. Having said all this, I thought about this topology and, perhaps, I will find time to refine it.

HV block and deflection device

I haven’t used a ferrite armor core for so long that I completely forgot about its electrical conductivity. This caused a breakdown between the top of the secondary and the grounded ferrite, causing several pairs of STN3NF06L primary side transistor drivers to fail. In the course of finding out the reason, I replaced them with a pair of more stable TO252 (100A / 8mΩ), able to withstand even the supply of 12V, 1A and run the transformer with short-circuited turns.

I was a bit confused to find that the SG3525 is available in both wide and narrow SOIC packages. As a result, the seat on the PCB turned out to be inappropriate, and a narrow part had to be ordered from the UK.

Deflection amplifier

Designing this subsystem turned out to be a daunting task, and so a lot of time was spent working with the SPICE simulator, which helped to understand all the nuances.

Here is a brief specification:

• unbalanced input 0..5V
• differential output >80Vp-p per arm
• at 210V current consumption less than 2mA
• 12V supply option
• no negative tires
• bandwidth >500kHz with less than 5° phase shift from design

Over the course of a few days, I explored several topologies, starting with a cascode push-pull circuit with a sink current source. Initially, only the stationary mode was tested and optimized. After reaching the basic values ​​​​of direct current, I took up the parameters of the alternating one. The capacitor connecting the emitters of a push-pull circuit (not surprisingly) has a significant effect on AC gain, frequency, phase characteristics, and appears to interact strongly with the emitter resistors as well as their associated drains.

Here, as an improvement, thermal stabilization by thermal bonding of output devices can be applied (considering that this is now SOT-233, this is not an easy task). As an alternative, of course, you can switch to their through-hole counterparts, which will greatly simplify the task.

It would be nice to use a circuit in which phase shift and gain would be less dependent. But the current simple option has already overcome many difficult technical hurdles, so the additional requirement would already be too onerous.

Controller board and DAC

Given that the main task of the microcontroller is to repetitively calculate a string of vector pairs every few tens of milliseconds, it seemed to me reasonable to use an inexpensive and simple option for this.

The obvious candidates were the ATmega328P and ST micro STM32F103C8T6. As a result, the first one was chosen solely for its wider opportunities and (once) popularity. In the process of assembling the board, it surprisingly turned out that I accidentally bought the controller of version “B”, but more on that later.

Overall, its board is simple and includes an FT232RL USB converter, a dual-channel 8-bit DAC, a joystick and button interface, an additional I2C interface, and a 5V regulator. It was possible to use the Arduino Nano with the motherboard, but the current solution was simple and easy to connect.

Controller and DAC board

System requirements are for single bus operation, which limits DAC selection. Initially, I took the TLC7528, which seems to have a current output, but upon closer examination, it turned out that it can be configured to work in voltage output mode. In combination with the TSH82 op-amps, this turned out to be a poor choice, as distortion, even at the lowest signal levels, was a few percent. I solved this problem by replacing the DAC with the AD7302, which has two voltage outputs and a 2µs settling time.

A few percent distortion can ruin everything

In hindsight, the distortion with the TLC7528 could be due to the limited input common-mode range of its associated TSH82s. This is easy to check by removing these op amps and drawing a Lissajous circle on the oscilloscope directly with the probes.

As a result, a number of design errors prompted me to rebuild this seemingly simple board: the choice of a DAC, the initial use of the FT232RL, and the lack of binding the corresponding TST pin to ground. I also made a mistake in the USB connector connection scheme on the board (mixed up the signal wires), which I temporarily corrected with a homemade cable.

New microcontroller, tool kit and loader

As I said, surprisingly, it turned out that the ATmega328P I ordered earlier turned out to be the less popular “B” variety in an incomprehensible way. They are fully binary-compatible with their younger counterparts, except for the chip signature. At the same time, the newer version has a number of useful additional features, including support for a second USART.

Arduino provides the latest set of tools that, oddly enough, was not available on the Atmel website. These tools had to be extracted and put together into a portable package, so they no longer relied on the Arduino framework. I then updated the project’s corresponding makefile to refer to the new controller and tools.

Due to chip compatibility, the standard Arduino bootloader was programmed on a newer one using the relatively small AVR Studio 4 IDE, which I chose for the simplicity of the interface. The XML description file for the new controller had to be created based on the old version. As a result, the main differences were its number and the corresponding signature.

The make utility and, accordingly, the makefile file were used to flash the project. With this approach, the toolset took only about 30MB, and not hundreds, as is the case with using “modern” integrated IDEs.

Real programmers don’t use IDE

Firmware

The system is designed to draw about 10K vector pairs per second. At a refresh rate of 50Hz, this means that 200 vectors can be drawn. After every 200 vectors (20ms) the foreground is signaled to update their list so that the game can run smoothly enough.

Several system processes require the ability to rotate vectors. At the same time, despite the obvious reasonableness of using a decimal value in the range 0..359degrees, such a solution will require the use of U16 and will be unnecessarily cumbersome. After some thought, I decided that it would be appropriate to process as much data as possible with S8 (+127 to -128). It is also suitable for representing X/Y coordinates (using an 8-bit DAC) to express an angle (approximately ±180 degrees).

Screen refresh is done via a timer interrupt and is the only way to control the DACs. The vectors are read from the ping or pong buffer and iterated until the buffer is switched by the foreground task. Each buffer starts at counter U8 and continues to the next available write point, followed by a read point. After that, it contains a list of X and Y values ​​stored in U8 format.

The direction of the spacecraft is changed by moving the joystick left/right. The ship itself is displayed as four points a la with a chevron from the Star Trek series, rotating around its center. Each vector requires a sin and cos lookup, 4 multiplications and two additions. In total, 37 calculations are obtained per rotation, which is approximately 200 instructions in total. The spaceship will always be drawn first, and the first vector pair will always be its nose, so in the output buffer this vector pair will be the starting point for launching rockets.

Rockets are launched by pressing the appropriate button. They fly out of the bow of the ship and continue on its current course. The destruction of a rocket, of which no more than 16 can be launched at the same time, occurs when it collides with an asteroid or when it reaches the visible radius of space. This flight model is based on drawing lines between the bow of the ship and the boundary of the visible radius, where delta X and delta Y are calculated at launch. Delta X/Y is a fixed point of 8.8, as is speed.

Ship in the center, asteroid below

Asteroid objects spawn at a random location in the radius and fly straight across it at an angle between 80 and 140 degrees. When they appear, a random starting and ending position is generated, which are then converted to Cartesian coordinates, and the question of a straight line is solved in much the same way as the situation with rockets.

When a rocket collides with an asteroid, both entities are destroyed and the current score counter is increased. The numerical display objects are taken from a “7-segment” lookup table.

The whole “heavy” process of the game is done with the “rotation” function, which is used to add an input object (asteroid, spaceship, 7-seg value, etc. ) to the output buffer. In addition, it allows the input object to rotate, as well as apply offset along the X and Y axes. At the same time, nothing prevents you from adding a 2×2 squad of alien ships to the input buffer, then taking them as a group and deploying them before rendering.

Mechanical

Making this cosmic device look aesthetically pleasing already required much more effort, although the process itself turned out to be much more interesting than I expected. Initially, the slope of the CRT case turned out to be noticeably lower than planned, and as a result it took several hours to find a way to cut the sliding locking segment so that the upper and lower parts could be connected in a suitable way.

Primary design

Just a few degrees can make a big difference. I was amazed at how much the aesthetic changed as a result, and how crooked the first option looked with the most developed angle.

Kit: CRT module, lower housing segment and front panel cover

The CRT is fixed with round MDF brackets glued to the top of the compartment. From the inside, these brackets are sheathed with elastic foam rubber on an adhesive basis.

Blank CRT front with case lock and PCB markings

It is difficult to see from the photographs that the control panel with joystick and buttons securely fixes the CRT module, preventing it from sliding back out.

Packages used to design the hull

For the initial design of the upper and lower segments of the case, the Inkscape editor with the extension “The Laser Cut Box” was used. Only jagged cutouts acted as a ligament of these segments. I simply copied the final workpiece from Inkscape and pasted it into Autosketch, in which I made all the necessary improvements.

I used a 70W laser cutter to cut MDF blanks. The work cycle turned out to be fast enough, which made it possible to test alternative design ideas in parallel.

Conclusion

As I expected, I was able to learn a lot on this project, since everything, except perhaps the built-in microcontroller, turned out to be beyond my narrow-minded experience.