Acromioclavicular (AC) Joint Injury

Fantasy Impact

PositionAverage % Difference PPG Change From Pre-Injury Compared to 1st Game After Injury
Average % Difference PPG Change From Pre-Injury Compared to Games 2-3 After Injury
Average % Difference PPG Change From Pre-Injury Compared to 1 Games 4-6 After Injury
QB-28.2%-10.9%-0.9%
RB-29.5%-32.5%-15%
WR-33%+3%+15%
TE-22%-29%+32.5%
PositionAverage Change in Snap% From Pre-Injury Compared to 1st Game After Injury
Average Change in Snap% From Pre-Injury Compared to Games 2-3 After Injury

Average Change in Snap% From Pre-Injury Compared to Games 4-6 After Injury

QB-2.9%+3.5%+3.8%
RB+52%+49%-26%
WR-10.3%-7.4%-0.9%
TE+40%+50%+67%

Anatomy of the AC joint

The Acromioclavicular (AC) joint is the junction of part of the scapula called the acromion to the clavicle (collar bone), and this connection is how it is given its name.1,2 The AC joint functionally links the shoulder girdle to the torso and is important for shoulder mobility and stability.2 The joint is highly dependent upon ligament support to hold it together, preventing injury. The ligaments involved in supporting the AC joint are the acromioclavicular ligament, which connects the end of the clavicle to the acromion, and the coracoclavicular (CC) ligaments, which comprised of two ligaments (conoid and trapezoid ligaments) that connect another part of the scapula called the coracoid process to the clavicle.1-3 There is also a capsule, which is a connective tissue surrounding the joint, helping provide support.1,2 Additionally, the deltoid and trapezius muscles also help provide support to the joint. 

An injury to the AC joint can be termed a “shoulder separation” and is when these ligaments become injured, allowing the connection between the acromion and clavicle to separate from one another.1,3 The degree of injury, and thus separation, is dependent upon the amount of damage to the ligaments and muscle (grades listed below).4 An important anatomical note is the term coracoclavicular interspace. This describes the space between the coracoid process and the clavicle. With certain grades of AC joint injuries, this space is altered from its normal position. Also, note that the term “avulsion” is used in a grade IV injury. An “avulsion” is when the tissue tears right off the bone.4

  • Grade I: Sprain of the AC ligament without complete tear, CC ligaments unharmed.4
  • Grade II: Complete tear of the AC ligaments, sprain of the CC ligaments.4
  • Grade III: Complete tear of the AC and CC ligaments, coracoclavicular interspace is 25%-100% greater than normal.4
  • Grade IV: Avulsion of the CC ligament from the clavicle with upwards and backwards separation of the clavicle into the trapezius muscle.4
  • Grade V: Complete tear of the AC and CC ligaments, coracoclavicular interspace is 100%-300% greater than normal (more exaggerated version of grade III).4
  • Grade VI: Clavicle is separated downward towards the coracoid process.4

The AC joint must undergo controlled motion when the arm raises above the head, like throwing or reaching up to catch a pass.3 Because of this, injury to the AC joint may alter an athlete’s ability to throw and catch, making this injury relevant to all fantasy eligible players.   

Cause of AC joint Injury

The most common cause of an AC joint injury is falling directly onto the shoulder while the arm is positioned across the body.5 This is often seen when tackled and landing hard on the point of the shoulder or diving to catch a ball. Falling onto an outstretched arm is another common way this injury occurs.1,2

The player in white is about to fall directly onto his left shoulder which will cause his arm to fold across his body, this is a common mechanism for AC joint injury

Studies show high rates of AC joint injuries in football players, with nearly 30% of all NFL shoulder injuries involving the AC joint, and nearly 40% of NFL QBs will experience an AC joint injury in their career.6,7

AC joint surgical procedure

Consensus in the medical community agrees that grade IV-VI AC joint injuries require surgery to properly restore the stability and function of the AC joint.2,3 Management of grade III AC joint injuries is much more complicated and often is trialed with conservative care; however, if unsuccessful will lead to surgery.2,3

Numerous surgical techniques are performed, and a detailed description of each is outside the scope of this article. In simplest terms, there are two categories of AC joint reconstruction; non-anatomic and anatomic.8 With A non-anatomic AC joint reconstruction, the surgeon will use hardware such as wires, pins, plates, and screws to restore the anatomical alignment of the joint. During an anatomic AC joint reconstruction, the surgeon will utilize a graft either from a cadaver (termed allograft) or harvested from another tissue within the patient’s body (termed autograft) to surgically replace the injured ligaments.8

Currently, there is no consensus on a gold standard best surgical technique for AC joint reconstruction. The technique is often determined by the patient’s post-operative goals (i.e., return to professional football) and surgeon training and preference.8

AC joint rehab process

The rehab process from an AC joint injury depends on the grade of injury, as this will often dictate if the injury is being treated surgically or conservatively.1-3,5 As mentioned above, there is general consensus that grade I and II injuries are best treated conservatively, and grades IV-VI are best treated surgically; however, there is a lack of consensus on grade III injuries.1-3,5 For grades I and II (and some grades III) injuries, there are four outlined phases of recovery that are discussed below.5,9,10 Progression through these phases is dependent upon athlete’s pain and function rather than a set time period.

For grades I and II and some grade III injuries, the initial phase of rehab involves immobilization in a sling, rest from activity, ice, and anti-inflammatory medication for pain control.1-3,5,9,10 During this phase, the sling is used typically for up to a week to allow inflammation and pain control; however, the immobilization period should be kept short as prolonged immobilization will lead to stiffness and weakness and slower return to playing.3,5 While in this phase, the athlete must take the sling off periodically throughout the day to perform elbow, wrist, and hand mobility exercises to prevent stiffness and weakness.3 The sling can be removed when there is no longer pain with the arm hanging by the side.

The second phase involves restoring shoulder range of motion and beginning strengthening.5 During this phase, the clinician will passively stretch the athlete’s shoulder in a forward and lateral direction, purposefully avoiding positions that may induce pain (crossing the arm over the body, rotating the arm inward).5 If tolerable, active-assisted range of motion can be performed in which the clinician will provide support while the athlete moves his arm into these positions.

Additionally, strengthening the shoulder blade and rotator cuff muscles is initiated and often begins with the hand supported on a table or wall to offload the arm and the AC joint.5 Shoulder blade and rotator cuff strength are imperative following AC joint injury as proper motion of the shoulder blade and arm with athletic motions is often altered following this injury, but is needed for throwing and catching performance and preventing injury recurrence.5 As pain continues to subside, motion in all directions can be performed, and active motion without support can be initiated.

When range of motion is pain-free and full, phase three can begin. In this phase, focus is on strength and stability of the shoulder. Rehab will continue to focus on shoulder blade and rotator cuff strength that consists of theraband or cable exercises, beginning to use dumbbells for resistance, as well as progression of weight-bearing exercises.5

Phase four focuses on restoring strength and beginning sport-related exercises. This includes exercises that incorporate the whole body, plyometrics such as medicine ball tosses, progressive strength training including pushups, bench presses, overhead presses, and for quarterbacks, a progressive throwing program beginning with short, low velocity throws and progressing to longer and higher velocity throws.5

Rehab Phases5,9,10 Treatments5,9,10
Phase IImmobilized in sling.
Rest, ice, anti-inflammatories.
Elbow, wrist, hand range of motion exercise.
Phase IIPassive and active-assisted shoulder range of motion into elevated and lateral directions.
Shoulder blade and rotator cuff strengthening in pain free positions.
Initiate exercises bearing weight on hands.
Progress to range of motion in all directions and active motion.
Phase IIITheraband, cable, and light dumbell exercises for shoulder blade and rotator cuff strength.
Progress weight bearing exercises.
Full body exercises incorporating the legs and core.
Phase IVProgress full body exercises.
Progressive strength training including bench press, push-ups, over head lifts.
Upper body plyometrics.
Progressive throwing program.
Disclaimer: This is a generic rehabilitation protocol for this injury, if you or someone you know believes they have a similar injury it is advised to seek local professional consultation

Often grade III injuries will attempt to rehab initially; however, if unsuccessful will be treated surgically. In many cases, athletes with grade III AC joint injuries who choose conservative care will not experience complete restoration of the normal anatomy, may not fully regain strength, and may experience lasting cosmetic deformities (Remember all the discussion about Keenan Allen’s shoulder during Hard Knocks?); however, the loss of these factors does not necessarily impact their athletic performance.8

Surgery is needed for grades IV-VI and some grade III AC joint injuries. The rehab following surgery lasts several months and would likely render an athlete out for the season, depending on when the injury occurs. There are four distinct phases of post-op rehab with different goals, precautions, and treatments performed during each.11,12

Phase of Rehab11,12 Goals and Precautions11,12 Rehab11,12
Phase I: Protection, Pain, and Swelling Control.

Post-Op Weeks 1-6
Goals
Protect Surgery.
Reduce pain and swelling.
Begin restoring ROM.
Prevent muscle atrophy.
Precautions
Sling worn at all times other than showering and exercises.
Do not elevate arm past 90°.
Avoid lifting objects >5lbs.
Avoid placing hand behind back or arm across body.
Ice 4-5 times/day.
Neck, elbow, wrist, hand range of motion.
Shoulder pendulums.
Passive stretching to 90° elevation, rotation to tolerance (with arm by side).
Gentle muscle isometrics to tolerance.
Phase II: Protection, ROM, and Initiation of Strength.

Post-Op Weeks 6-12
Goals
Protect surgery.
Reduce pain and swelling.
Continue progressing ROM.
Gradually increase strength.
Precautions
No pushups or pushing movements.
No lifting weighted objects overhead or across body.
Wean out of sling.
Continue icing 4-5 times/day.
Slowly progress ROM in all directions (increase ~15°/week as tolerable).
Begin active assisted ROM progressing to active ROM when able.
Continue with muscle isometrics progressing to active shoulder exercises without weight and theraband exercises when tolerable.
Scapular strength exercises.
Phase III: Full ROM and Strengthening.

Post-Op Weeks 12-18
Goals
Full ROM.
Improve strength, power, endurance, and control.
Precautions
No deadlifts of pressing exercises.
No contact.
Continue ROM until full.
Continue progressing shoulder and scapular exercises beginning to add resistance via bands, cable, light dumbbells.
Begin wall pushups at 12 weeks.
True weight training beginning at 16 weeks.
Phase IV: Advancing Strength and Sports Specific.

Post-Op Weeks 18+
Goals
Restore full strength, mobility, stability.
Return to sport.
Continue stretching as needed.
Unrestricted strength training.
Upper body plyometrics.
Sports-specific training (throwing program, catching, running)
Disclaimer: This is a generic rehabilitation protocol for this injury, if you or someone you know believes they have a similar injury it is advised to seek local professional consultation.
Post-op protocol adapted from Massachusetts General Hospital Orthopedics and Northwestern Medical Center

Players who have had an AC joint injury

Quarterbacks

Kyler Murray AC joint injury
Kyler Murray was able to play through an AC injury in 2020 however, his fantasy production dropped significantly
QuarterbacksGames MissedPPG Prior to InjuryPPG 1st Game After InjuryPPG Games 2-3 After InjuryPPG Games 4-6 After Injury
Sam Darnold (2021 week 8)016.64.8 (-11.8)N/AN/A
Kyler Murray (2020 week 11)0318.9 (-22.1)18 (-13)18.1 (-12.9)
Sam Darnold (2020 week 8)μ29.56.8 (-2.7)13.3 (+3.8)14.7 (+5.2)
Sam Darnold (2020 week 4)211.82.8 (-9)N/AμN/Aμ
Jameis Winston (2017 week 9)μ316.718.6 (+1.9)20.1 (+3.4)18.5 (+1.8)
Jameis Winston (2017 week 6)016.623.4 (+6.8)3.7 (-12.9)μN/Aμ
Average1.1-6.2-4.7-2
Number of Players Who Have Met Their Baseline at Current or Previous Time Points2/6 (33%)2/6 (33%)2/6 (33%)
*Based on 0.5 PPR and 4pt passing TD scoring. *Indicates 1 game was played in the time span. ρ Indicates inclusion of playoff games. μ Indicates re-injury.

Running Backs

Christian McCaffrey AC joint injury
In 2020 Christian McCaffrey suffered an AC joint injury that kept him out 4 games.
Running BacksGames MissedPPG Prior to InjuryPPG 1st Game After InjuryPPG Games 2-3 After InjuryPPG Games 4-6 After Injury
D’Andre Swift (2021 week 12)416.84.9 (-11.9)12.6 (-4.2)*N/A
Christian McCaffrey (2020 week 9)424.432.1 (+7.7)N/AN/A
Carlos Hyde (2020 week 3)28.315.1 (+6.8)N/AN/A
Dalvin Cook (2019 week 15)217.926.5 (+8.6)ρ5.6 (-12.3)*ρN/A
Spencer Ware (2019 week 16)42.6N/AN/AN/A
James Conner (2019 week 8)514.613.1 (-1.5)N/AN/A
Chris Ivory (2018 week 13)μ259.6 (+4.6)N/AN/A
Chris Ivory (2018 week 9)16.41.4 (-5)2.3 (-4.1)N/Aμ
Damien Williams (2017 week 12)56.3N/AN/AN/A
Average3.2+1.3-6.9N/A
Number of Players Who Have Met Their Baseline at Current or Previous Time Points4/7 (57%)4/7 (57%)N/A
*Based on 0.5 PPR and 4pt passing TD scoring. *Indicates 1 game was played in the time span. ρ Indicates inclusion of playoff games. μ Indicates re-injury.

Wide Receivers

Tyreek Hill AC joint injury
Tyreek Hill suffered a AC joint dislocation in the first week of 2019 that kept him out 4 weeks.
Wide RecieversGames MissedPPG Prior to InjuryPPG 1st Game After InjuryPPG Games 2-3 After InjuryPPG Games 4-6 After Injury
Quez Watkins (2022 week 13)06.63.9 (-2.7)3.2 (-3.4)
Odel Beckham Jr. (2021 week 6)06.13.3 (-2.8)2 (-4.1)14.4 (+8.3)
Marvin Jones Jr. (2021 preseason)01616.2 (+0.2)11.9 (-4.1)8.8 (-7.2)
Courtland Sutton (2020 week 1)198.1 (-0.9)N/AN/A
Mike Williams (2020 preseason)010.48.9 (-1.5)2.3 (-8.1)14.9 (+4.5)
Julio Jones (2019 week 12)112.49.1 (-3.3)26.8 (+14.4)11.3 (-1.1)*
Julian Edelman (2019 week 11)014.612.4 (-2.2)16.1 (+1.5)11.3 (-3.3)
James Washington (2019 week 5)13.32.6 (-0.7)12.5 (+9.2)14.4 (+11)
Tyreek Hill (2019 week 1)417.622.5 (+4.9)13 (-4.6)17 (-0.6)
DeAndre Hopkins (2018 playoffs)017.3 N/AN/AN/A
Chris Hogan (2017 week 14)μ313.4N/AN/AN/A
Robert Woods (2017 week 11)313.813.5 (-0.3)11.6 (-2.2)ρN/A
Chris Hogan (2017 week 8)413.40.6 (-12.8)μN/AμN/Aμ
Average1.3-2.0-1.5+1.7
Number of Players Who Have Met Their Baseline at Current or Previous Time Points2/11 (18%)5/9 (56%)7/7 (100%)
*Based on 0.5 PPR and 4pt passing TD scoring. *Indicates 1 game was played in the time span. ρ Indicates inclusion of playoff games. μ Indicates re-injury.

Tight Ends

Tight EndsGames MissedPPG Prior to InjuryPPG 1st Game After InjuryPPG Games 2-3 After InjuryPPG Games 4-6 After Injury
Jeremey Ruckert (2023 Preseason)01.30 (-1.3)
Vance McDonald (2019 week 3)18.24.9 (-3.3)2.2 (-6)6.4 (-1.8)
Darren Waller (2019 preseason)03.210.5 (+7.3)16 (+12.8)15.1 (+11.9)
George Kittle (2018 preseason)06.311.5 (+5.2)7.8 (+1.5)12.4 (+6.1)
Average0.3+3+2.8+5.4
Number of Players Who Have Met Their Baseline at Current or Previous Time Points2/4 (50%)2/3 (66%)2/3 (66%)
*Based on 0.5 PPR and 4pt passing TD scoring. *Indicates 1 game was played in the time span. ρ Indicates inclusion of playoff games. μ Indicates re-injury.


Tom Christ, PT, DPT, OCS

References

  1. Sueki D, Brechter J. Orthopedic Rehabilitation Clinical Advisor. 1st ed. Maryland Heights, MO. Elsevier Inc.; 2010.
  2. Nolte P, Lacheta L, Dekker T, Elrick B, Millett P. Optimal Management of Acromioclavicular Dislocation: Current Perspectives. Orthop Res Rev. 2020;12:27-44.
  3. Deans C, Gentile J, Tao M. Acromioclavicular joint injuries in overhead athletes: a concise review of injury mechanisms, treatment options, and outcomes. Curr Rev Musculoskelet Med. 2019;12(2):80-86.
  4. Rockwood C, Williams G, Young D. Disorders of the acromioclavicular joint. 2nd ed. Philadelphia: WB Saunders; 1990.
  5. LeVasseur M, Mancini M, Berthold D, et al. Acromioclavicular Joint Injuries: Effective Rehabilitation. Open Access J. Sports Med. 2021:12;73-85.
  6. Lynch TS, Saltzman MD, Ghodasra JH, Bilimoria KY, Bowen MK, Nuber GW. Acromioclavicular joint injuries in the National Football League: epidemiology and management. Am J Sports Med. 2013;41(12):2904–2908.
  7. Kelly BT, Barnes RP, Powell JW, Warren RF. Shoulder injuries to quarterbacks in the National Football League. Am J Sports Med. 2004;32:328–331.
  8. Virk M.S, Apostolakos J, Cote M.P, Baker B, Beitzel K, Mazzocca A.D. Operative and Nonoperative Treatment of Acromioclavicular Dislocation. J Bone Joint Surg. 2015;3(10).
  9. Gladstone JN, Wilk KE, Andrews JR. Nonoperative treatment of acromioclavicular joint injuries. Oper Tech Sports Med. 1997;5:78–87.
  10. Cote MP, Wojcik KE, Gomlinski G, Mazzocca AD. Rehabilitation of acromioclavicular joint separations: operative and nonoperative considerations. Clin Sports Med. 2010;29:213–228.
  11. Massachusetts General Hospital Orthopedics.  Shoulder Separation and Acromioclavicular Joint Injury.  Massachusetts General Hospital Orthopedics. https://www.massgeneral.org/assets/MGH/pdf/orthopaedics/sports-medicine/physical-therapy/rehabilitation-protocol-for-AC-joint-reconstruction.pdf.  Accessed April 17 2022.
  12. Northwestern Medical Center.  AC Joint Reconstruction Protocol.  Northwestern Medical Center. https://www.northwesternmedicalcenter.org/pdf/ac-joint-reconstruction-protocol/.  Published December 2016.  Updated December 2016.  Accessed April 17 2022.

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