Classification
- Type: Secondary cartilaginous joint (symphysis); may partially or fully ossify (fuse) with age
- Degrees of freedom: Minimal — slight flexion/extension (nutation/counternutation of the coccyx)
- Region: Distal sacrum/coccyx (inferior to the anatomy/joints/sacroiliac and anatomy/joints/lumbosacral joints)
Articular Surfaces
- Sacral apex (inferior S5): An oval surface on the inferior tip of the sacrum
- Coccygeal base (Co1): The superior surface of the first coccygeal segment
- Fibrocartilaginous disc: A thin disc separates the two surfaces, similar to other symphysis joints. The disc progressively calcifies and may ossify completely, particularly in older males.
- Intercoccygeal joints: The coccyx typically comprises 3–5 fused or semi-fused segments. The joints between coccygeal segments (Co1-Co2, Co2-Co3, etc.) are variably mobile or fused.
Movements and ROM
| Movement |
Normal ROM |
Description |
| Flexion (nutation) |
5–15° |
The coccyx tips anteriorly (toward the pubic symphysis) — occurs during sitting |
| Extension (counternutation) |
5–15° |
The coccyx tips posteriorly — occurs during standing and during defecation |
Coccygeal motion during sitting. When a person sits, the coccyx flexes (tips anteriorly) under body weight. The degree of flexion depends on the sitting surface — hard chairs produce more coccygeal compression than soft chairs. The coccyx absorbs a significant portion of seated body weight (particularly in the reclined or slouched position, where the ischial tuberosities shift posteriorly and more weight transfers to the coccyx).
Capsular Pattern
Not applicable — this is a symphysis, not a synovial joint.
Ligaments
Anterior Sacrococcygeal Ligament
- Attachments: Anterior sacral apex → anterior coccygeal base
- Function: Resists coccygeal extension (posterior tipping); continuous with the anterior longitudinal ligament
Posterior Sacrococcygeal Ligament
- Attachments: Posterior sacral canal → posterior coccyx
- Function: Resists coccygeal flexion (anterior tipping); continuous with the posterior longitudinal ligament. A superficial and deep layer exists. The superficial layer bridges the sacral hiatus.
Lateral Sacrococcygeal Ligaments
- Attachments: Inferior lateral sacrum → transverse processes of the coccyx
- Function: Lateral stabilization
Sacrotuberous Ligament (Relevant)
- Attaches partly to the lateral coccyx; tension on this ligament affects coccygeal position
Sacrospinous Ligament (Relevant)
- Attaches partly to the coccyx; similarly affects coccygeal mechanics
Mobilization Techniques
Hands-on instruction is required. The descriptions below provide clinical reference detail for understanding and supervised practice. They are not a substitute for instructor-led technique training. Correct hand placement, force dosage, and tissue response interpretation require hands-on coaching and feedback.
Important Considerations
Coccygeal mobilization can be performed externally or intrarectal. External mobilization is the standard approach for most manual therapists. Intrarectal mobilization is more effective but requires additional training, explicit informed consent, and may be outside the scope of practice depending on jurisdiction. Always verify scope of practice before performing intrarectal techniques.
General Contraindications
- Absolute: Coccygeal fracture (acute), coccygeal tumor (chordoma is the most common primary sacrococcygeal tumor), pilonidal cyst/abscess (infection near the coccyx), rectal pathology (fissure, hemorrhoids, abscess — if intrarectal technique is planned), active infection
- Relative: Pregnancy (avoid prone positioning; modify technique), fused sacrococcygeal joint (common in elderly males — mobilization is ineffective against ankylosis), patient refusal (coccygeal techniques require sensitive communication and explicit consent)
External Coccygeal Mobilization
Purpose: Restores sacrococcygeal flexion/extension mobility. Used for coccydynia caused by sacrococcygeal hypomobility or malalignment.
Patient position:
- Side-lying (preferred for patient comfort and dignity) or prone
- Hips and knees slightly flexed
Hand placement:
- Mobilizing hand: The clinician's thumb or finger pad contacts the posterior coccyx (palpated as a small, pointed or rounded bony prominence in the gluteal cleft, inferior to the sacrum). Ensure the contact is on the coccyx, not the anus.
Technique execution:
- Apply gentle pressure directing the coccyx anteriorly (for extension mobilization — restoring the ability of the coccyx to flex during sitting) or supporting the coccyx while it is moved gently through its flexion/extension range
- Grade I–II: Very gentle oscillations — the sacrococcygeal joint is small and often tender
- Duration: 15–30 seconds, 2–3 sets
- Reassess seated comfort between sets
Indications:
- Coccydynia (coccyx pain) not responding to gluteal and pelvic floor treatment
- Post-traumatic coccygeal malalignment (anterior or lateral coccygeal displacement after a fall)
- Chronic sitting intolerance with coccygeal tenderness
Technique notes:
- Communication is essential. Coccygeal work involves a sensitive area. Explain the technique, its purpose, and obtain explicit verbal consent before proceeding. Offer a chaperone.
- Common error: Using too much force — the sacrococcygeal joint requires very little force.
- Reassessment: Have the patient sit on a hard chair. Reduced pain with sitting confirms coccygeal involvement.
Muscles Attaching to the Coccyx
- anatomy/muscles/gluteus-maximus — the largest muscle in the body; attaches to the lateral coccyx and sacrotuberous ligament; its traction on the coccyx can perpetuate coccygeal malalignment
- anatomy/muscles/levator-ani (iliococcygeus and pubococcygeus) — pelvic floor muscles attaching to the coccyx; their hypertonicity is a common perpetuating factor in coccydynia
- anatomy/muscles/coccygeus (ischiococcygeus) — pelvic floor muscle from the ischial spine to the coccyx; supports the coccyx and contributes to pelvic floor function
- Sacrotuberous and sacrospinous ligaments — attach to the coccyx; their tension affects coccygeal position
Conditions Affecting This Joint
- Coccydynia — pain in the coccygeal region, typically worsened by sitting (especially on hard surfaces) and transitioning from sitting to standing; causes include trauma (fall onto buttocks), delivery injury, pelvic floor dysfunction, hypomobility or hypermobility of the sacrococcygeal joint, and idiopathic
- Coccygeal fracture — acute fracture from a fall directly onto the coccyx; produces severe pain with sitting, defecation, and any pressure on the coccyx; usually treated conservatively (cushion, pain management, mobilization after healing)
- Coccygeal malalignment — anterior, posterior, or lateral displacement of the coccyx following trauma; confirmed on lateral radiograph or dynamic radiographs (sitting vs. standing)
- Chordoma — a rare but serious primary bone tumor arising from notochordal remnants in the sacrococcygeal region; slow-growing but locally aggressive; presents as progressive coccygeal or sacral pain; requires referral
Clinical Notes
- Coccydynia is more common than appreciated. It accounts for approximately 1% of all spinal pain complaints but is frequently underdiagnosed because patients are embarrassed to report pain in this area. Always ask specifically about sitting pain and coccygeal tenderness in patients with "low back pain" — particularly if the pain is worse with sitting and transitioning.
- Pelvic floor hypertonia is the most common perpetuating factor. The levator ani and coccygeus attach directly to the coccyx. Chronic pelvic floor hypertonicity (from stress, guarding, post-delivery trauma) maintains coccygeal tension and prevents recovery. Pelvic floor relaxation techniques (diaphragmatic breathing, pelvic floor "drops") are essential alongside coccygeal mobilization.
- The gluteus maximus can maintain coccygeal malalignment. The gluteus maximus attaches to the lateral coccyx. Unilateral gluteal hypertonia or spasm can pull the coccyx laterally, producing asymmetric coccydynia. Always assess and treat gluteus maximus before coccygeal mobilization.
- Seated cushions provide immediate relief. A coccygeal cutout cushion (donut or wedge cushion with the posterior section removed) offloads the coccyx during sitting. This is the most effective immediate intervention for coccydynia and should be recommended while treatment addresses the underlying cause.
Key Takeaways
- The sacrococcygeal joint permits 5–15° of flexion/extension — the coccyx flexes during sitting and extends during standing; loss of this motion produces sitting pain.
- Pelvic floor hypertonia is the most common perpetuating factor in coccydynia — pelvic floor relaxation is essential alongside coccygeal mobilization.
- Always assess the gluteus maximus and pelvic floor before attributing pain to the sacrococcygeal joint itself — soft tissue causes are more common than joint causes.
- A coccygeal cutout cushion provides immediate relief while treatment addresses the underlying cause.
