Abstract
Loose bodies of the posterior ankle can occur either at the posterior recess of the ankle or subtalar joint or at the posterior ankle extra-articular space. Loose bodies at the extra-articular space can be a result of tenosynovial chondromatosis of the tendons of the posterior ankle, especially the flexor hallucis longus tendon. Endoscopic removal of loose bodies of the posterior ankle extra-articular space is indicated for symptomatic cases that are not improved by conservative treatment. It is contraindicated if there is active infection at the planned portal sites or the surgeon is not familiar with the technique of posterior ankle endoscopy. Systematic assessment of the different parts of the posterior ankle will minimize the risk of loose body retention.
Synovial chondromatosis is characterized by the formation of multiple cartilaginous nodules in the synovium of the joints, tendon sheaths, or bursae. If the disease is intra-articular, the condition is referred to as “synovial chondromatosis”; if extra-articular in the tendon sheath, “tenosynovial chondromatosis.” Both tenosynovial chondromatosis and synovial chondromatosis have similar histologic features.1 In the early histologic phase, there is active synovitis without loose bodies in the joint. The second, transitional phase shows nodular synovitis along with loose bodies in the joint. In the third phase, loose bodies are present but the synovitis has resolved.2 Loose bodies of the posterior ankle can occur either at the posterior recess of the ankle or subtalar joint or at the posterior ankle extra-articular space. Loose bodies at the extra-articular space can be a result of tenosynovial chondromatosis of the tendons of the posterior ankle, especially the flexor hallucis longus (FHL) tendon.3, 4, 5, 6, 7 The extra-articular loose bodies can also come from synovial chondromatosis of the ankle or posterior subtalar joint because there is communication between the ankle joint and FHL tendon sheath in 25% of the normal population.7, 8, 9, 10 In this report, the technical details of endoscopic removal of loose bodies of the posterior ankle extra-articular space are described. This technique is indicated for symptomatic loose bodies of the posterior ankle extra-articular space arising from FHL tenosynovial osteochondromatosis that are not improved by conservative treatment. It is contraindicated if there is active infection at the planned portal sites or the surgeon is not familiar with the technique of posterior ankle endoscopy (Table 1).
Table 1.
Indications and Contraindications of Endoscopic Removal of Loose Bodies From Posterior Ankle Extra-articular Space
| Indications |
| Symptomatic loose bodies of the posterior ankle extra-articular space arising from flexor hallucis longus tenosynovial osteochondromatosis that are not improved by conservative treatment |
| Contraindications |
| Active infection at the planned portal sites |
| Surgeon's unfamiliarity with the technique of posterior ankle endoscopy |
Technique
Preoperative Planning and Patient Positioning
Preoperative radiographs and magnetic resonance imaging of the ankle are important to define the extent of the disease (Fig 1). The patient should be informed about the possibility of incomplete removal of the loose bodies and recurrence of the condition after the procedure.
Fig 1.
Endoscopic removal of loose bodies from right posterior ankle extra-articular space. (A) A preoperative lateral ankle radiograph of the presented case shows multiple loose bodies (arrowheads) of the posterior ankle. (B-D) Sagittal views on preoperative magnetic resonance imaging show loose bodies (arrowheads) at the synovial pouch adjacent to the flexor hallucis longus muscle (B), posterior ankle extra-articular space proper (C), and medial wall of the posterior ankle (D). (A, anterior; P, posterior.)
The patient is placed in the prone position. A thigh tourniquet is applied to provide a bloodless surgical field. A 4.0-mm 30° arthroscope (Dyonics; Smith & Nephew, Andover, MA) is used for this procedure.
Placement of Posterior Portals
The posterolateral and posteromedial portals are located at the lateral and medial side of the Achilles tendon just above the posterior calcaneal tubercle. Five-millimeter incisions are made at these 2 portal sites, and the subcutaneous tissue and investing fascia are bluntly dissected by a hemostat to the extra-articular space. Posteromedial ankle endoscopy is performed with these 2 portals (Fig 2).11 The posteromedial portal is later extended proximally for removal of large loose bodies and subsequent zone 2 FHL tendoscopy.3, 12
Fig 2.
Endoscopic removal of loose bodies from right posterior ankle extra-articular space. The patient is in the prone position. Posterior ankle endoscopy is performed through the posteromedial portal (PMP) and posterolateral portal (PLP).
Removal of Loose Bodies of Posterior Ankle Extra-articular Space Proper
The posterolateral portal is the viewing portal. The posterior ankle extra-articular space proper is examined for loose bodies. Small freely mobile loose bodies can be identified by opening a hemostat or suction by an arthroscopic shaver (Dyonics; Smith & Nephew) in the extra-articular space proper. These maneuvers can create a vacuum effect, and the loose bodies will move toward the instruments. The large loose bodies of the extra-articular space proper should be removed to gain access to other regions of the posterior ankle. The posteromedial portal incision is extended proximally to facilitate removal of the large loose bodies. The large loose bodies are then removed by a hemostat through the posteromedial portal (Fig 3).
Fig 3.
Endoscopic removal of loose bodies from right posterior ankle extra-articular space. The posterolateral portal (PLP) is the viewing portal. (A) A large loose body (LB) is shown in the posterior ankle extra-articular space proper (EAS). (B) The loose body is removed by a hemostat through the posteromedial portal (PMP).
Removal of Loose Bodies of Medial and Lateral Walls of Posterior Ankle Extra-articular Space
The medial and lateral walls of the posterior ankle are probed gently for any loose bodies adherent to the walls. For the loose bodies of the medial wall, the surgeon should be aware of the relation between the loose bodies and the tibial neurovascular bundle at the tarsal tunnel (Fig 4). The posterolateral portal is the viewing portal. The loose body should be peeled off so that it will move away from the neurovascular bundle. This can be performed by means of an arthroscopic probe (Arthrex, Naples, FL) through the posteromedial portal. Because the loose body is at the deep side of the tarsal tunnel and posterior to the neurovascular bundle, it should be peeled off posteriorly away from the bundle and toward the extra-articular space. Large and soft loose bodies can be removed in piecemeal.
Fig 4.
Endoscopic removal of loose bodies from right posterior ankle extra-articular space. The posterolateral portal is the viewing portal. A loose body (LB) is found at the medial wall of the posterior ankle and is posterior to the tibial neurovascular bundle (TNVB).
Removal of Loose Bodies From Posteromedial and Posterolateral Ankle Gutters
The posteromedial and posterolateral gutters of the ankle are probed for any loose bodies. The encapsulated loose bodies can be enucleated by an arthroscopic shaver or arthroscopic probe (Fig 5). The loose bodies will drop into the extra-articular space proper and can be removed by an arthroscopic grasper (Arthrex). The 2 portals can be switched to serve as the viewing and working portals. The ankle should undergo plantar flexion during removal of loose bodies from the posteromedial ankle gutter to avoid impingement of the tibial neurovascular bundle by the instrument through the posteromedial portal. The other solution is removal of loose bodies from the posteromedial ankle gutter through the posterolateral portal with the posteromedial portal as the viewing portal.
Fig 5.
Endoscopic removal of loose bodies from right posterior ankle extra-articular space. The posterolateral portal is the viewing portal. A loose body (LB) of the posteromedial ankle gutter is enucleated by an arthroscopic shaver through the posteromedial portal. (FHL, flexor hallucis longus tendon.)
Removal of Loose Bodies From Zone 1 FHL Tendon and Muscle
The posterolateral portal is the viewing portal. The FHL tendon at the posterior ankle (zone 1) is identified and traced proximally. The fascia covering the FHL muscle is released by arthroscopic scissors (Arthrex). The inflamed synovium and loose bodies of the FHL are exposed (Fig 6). The loose bodies are peeled off and removed by an arthroscopic grasper.
Fig 6.
Endoscopic removal of loose bodies from right posterior ankle extra-articular space. The posterolateral portal is the viewing portal. Loose bodies (LB) are found in the synovial pouch lateral to the flexor hallucis longus muscle (FHLm).
Endoscopic Synovectomy
Biopsy of the synovium, especially the synovium budding, is performed (Fig 7). Endoscopic synovectomy is performed by an arthroscopic shaver. The posteromedial and posterolateral portals are interchangeable as the viewing and working portals during this procedure.
Fig 7.
Endoscopic removal of loose bodies from right posterior ankle extra-articular space. The posterolateral portal is the viewing portal. Budding (B) from the inflamed synovium (S) is found around the flexor hallucis longus tendon (FHL).
Examination of Zone 2 FHL Tendon
After complete removal of loose bodies and synovectomy of the posterior ankle extra-articular space, the FHL tendon sheath under the sustentaculum tali (zone 2) can be examined by zone 2 FHL tendoscopy. The posterolateral portal is the viewing portal. A Wissinger rod (Dyonics; Smith & Nephew) is inserted through the posteromedial portal into the zone 2 tendon sheath under the sustentaculum tali. The arthroscope cannula is inserted into the zone 2 FHL tendon sheath along the Wissinger rod. The rod is removed, and the arthroscope is inserted into the cannula. The zone 2 FHL tendon sheath is examined for any synovitis or loose bodies (Fig 8, Video 1). If diseased synovium and loose bodies are present, synovectomy and removal of loose bodies can be performed through a plantar portal (Fig 9).3, 12
Fig 8.
Endoscopic removal of loose bodies from right posterior ankle extra-articular space. Zone 2 flexor hallucis longus tendoscopy is performed. (A) A Wissinger rod is inserted into the flexor hallucis longus tendon sheath under the sustentaculum tali through the posteromedial portal. (B) The arthroscope cannula is inserted along the rod. (PMP, posteromedial portal.) (C) The rod is exchanged with an arthroscope. (D) An arthroscopic view of the zone 2 flexor hallucis longus (FHL) tendon sheath shows no tenosynovitis or loose bodies.
Fig 9.
Endoscopic removal of loose bodies from right posterior ankle extra-articular space. (A) Loose bodies removed from posterior ankle extra-articular space in presented case. (B) A postoperative lateral ankle radiograph shows that the posterior ankle was free of loose bodies.
Discussion
Multiple loose bodies of the posterior ankle can be removed openly through the posteromedial or posterolateral approach. However, the open approaches may not be able to assess the posterior ankle thoroughly or may require a large incision and extensive retraction of the surgical wound. This implies a risk of soft-tissue complications. Posterior ankle endoscopy is a useful therapeutic tool for the treatment of various pathologies of the posterior ankle.11 Endoscopic removal of loose bodies has the advantages of fewer wound complications, thorough assessment of the posterior ankle, possible access to the FHL tendon sheath under the sustentaculum tali, and access to the posterior recesses of the ankle and posterior subtalar joints, if indicated. The extra-articular space proper and its walls can be assessed. Although not shown in the presented case, the Achilles tendon (posterior wall of the posterior ankle extra-articular space) also can be approached through the posteromedial and posterolateral portals. The major risk of this approach is injury to the tibial neurovascular bundle during synovectomy of the FHL tendon, during removal of loose bodies from the medial wall or the posteromedial ankle gutter, or during zone 2 FHL tendoscopy.13 The details of the technique as described earlier should be strictly followed to avoid this complication. Other potential risks include incomplete removal of loose bodies; injury to the sural nerve or calcaneal branch of the tibial nerve; and injury to the tendons of the posterior ankle, especially the FHL tendon (Table 2). Systematic assessment of the different parts of the posterior ankle will minimize the risk of loose body retention. Intraoperative fluoroscopy may be helpful to detect the osteochondral loose bodies but not the chondral ones. Posterior capsulotomy of the ankle and subtalar joints should only be performed if there is concomitant synovial chondromatosis of the joints. Otherwise, the joints may be “contaminated” by the diseased synovium of the posterior ankle. Similarly, zone 2 FHL tendoscopy should only be performed after complete synovectomy and removal of loose bodies of the posterior ankle. This will avoid spreading of synovitis or dropping of loose bodies into the zone 2 FHL tendon sheath (Table 3).
Table 2.
Advantages and Risks of Endoscopic Removal of Loose Bodies From Posterior Ankle Extra-articular Space
| Advantages |
| Better cosmesis |
| Less soft-tissue dissection |
| Thorough assessment of posterior ankle |
| Ability to approach posterior recesses of ankle and posterior subtalar joints and zone 2 FHL tendon sheath if indicated |
| Risks |
| Injury to posterior tibial neurovascular bundle |
| Injury to sural nerve |
| Injury to calcaneal branch of tibial nerve |
| Injury to tendons of posterior ankle, especially FHL tendon |
FHL, flexor hallucis longus.
Table 3.
Pearls and Pitfalls of Endoscopic Removal of Loose Bodies From Posterior Ankle Extra-articular Space
| Pearls |
| The large loose bodies of the extra-articular space proper should be removed first to gain access to other parts of the posterior ankle. |
| Loose bodies of the medial wall should be peeled off away from the tibial neurovascular bundle. |
| The FHL tendon should be traced proximally to expose the FHL muscle and diseased synovium and loose bodies of the muscle. |
| The ankle should undergo plantar flexion during instrumentation of the posteromedial ankle and during zone 2 FHL tendoscopy. |
| Pitfalls |
| Posterior ankle and subtalar capsulotomy should not be performed unless there is concomitant synovial chondromatosis of the joints. |
| Zone 2 FHL tendoscopy should only be performed after complete synovectomy and removal of loose bodies of the posterior ankle. |
FHL, flexor hallucis longus.
Footnotes
The author reports that he has no conflicts of interest in the authorship and publication of this article.
Supplementary Data
Endoscopic removal of loose bodies from right posterior ankle extra-articular space. The posterolateral portal is the viewing portal. The loose bodies of the posterior ankle extra-articular space proper are removed to gain access to other parts of the posterior ankle. The small freely mobile loose bodies can be fished out by opening a hemostat or suction by an arthroscopic shaver in the extra-articular space proper. The loose body of the medial wall is peeled off and removed. The encapsulated loose bodies of the posteromedial ankle gutter are enucleated and removed. The flexor hallucis tendon is exposed and traced proximally to expose the muscle. Loose bodies around the tendon and muscle are removed. Synovial biopsy and complete synovectomy are performed. Finally, zone 2 flexor hallucis longus tendoscopy is performed through the posteromedial portal.
References
- 1.Ueo T., Kashima K., Daa T. A case of tenosynovial chondromatosis with tophus-like deposits. APMIS. 2004;112:624–628. doi: 10.1111/j.1600-0463.2004.apm1120911.x. [DOI] [PubMed] [Google Scholar]
- 2.Milgram J.W. Synovial osteochondromatosis: A histopathological study of 30 cases. J Bone Joint Surg Am. 1977;59:792–801. [PubMed] [Google Scholar]
- 3.Lui T.H. Endoscopic loose body removal from zone 2 flexor hallucis longus tendon sheath. Arthrosc Tech. 2016;5:e465–e469. doi: 10.1016/j.eats.2016.01.026. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Sugimoto K., Iwai M., Kawate K., Yajima H., Takakura Y. Tenosynovial osteochondromatosis of the tarsal tunnel. Skeletal Radiol. 2003;32:99–102. doi: 10.1007/s00256-002-0594-9. [DOI] [PubMed] [Google Scholar]
- 5.Van P., Wilusz P.M., Ungar D.S., Pupp G.R. Synovial chondromatosis of the subtalar joint and tenosynovial chondromatosis of the posterior ankle. J Am Podiatr Med Assoc. 2006;96:59–62. doi: 10.7547/0960059. [DOI] [PubMed] [Google Scholar]
- 6.Oakley J., Yewlett A., Makwana N. Tenosynovial osteochondromatosis of the flexor hallucis longus tendon. J Foot Ankle Surg. 2010;16:148–150. doi: 10.1016/j.fas.2008.12.004. [DOI] [PubMed] [Google Scholar]
- 7.Lui T.H. Tenosynovial osteochondromatosis of the flexor hallucis longus tendon treated by tendoscopy. J Foot Ankle Surg. 2015;54:758–764. doi: 10.1053/j.jfas.2015.04.003. [DOI] [PubMed] [Google Scholar]
- 8.Haller J., Resnick D., Sartoris D., Mitchell M., Howard B., Gilula L. Arthrography, tenography, and bursography of the ankle and foot. Clin Podiatr Med Surg. 1988;5:893–903. [PubMed] [Google Scholar]
- 9.Na J.B., Bergman A.G., Oloff L.M., Beaulieu C.F. The flexor hallucis longus: Tenographic technique and correlation of imaging findings with surgery in 39 ankles. Radiology. 2005;236:974–982. doi: 10.1148/radiol.2362040835. [DOI] [PubMed] [Google Scholar]
- 10.Olson R.W. Arthrography of the ankle: Its use in the evaluation of ankle sprains. Radiology. 1969;92:1439–1446. doi: 10.1148/92.7.1439. [DOI] [PubMed] [Google Scholar]
- 11.van Dijk C.N., Scholten P.E., Krips R. A 2-portal endoscopic approach for diagnosis and treatment of posterior ankle pathology. Arthroscopy. 2000;16:871–876. doi: 10.1053/jars.2000.19430. [DOI] [PubMed] [Google Scholar]
- 12.Lui T.H. Flexor hallucis longus tendoscopy: A technical note. Knee Surg Sports Traumatol Arthrosc. 2009;17:107–110. doi: 10.1007/s00167-008-0623-x. [DOI] [PubMed] [Google Scholar]
- 13.Lui T.H. Lateral plantar nerve neuropraxia after FHL tendoscopy: Case report and anatomic evaluation. Foot Ankle Int. 2010;31:828–831. doi: 10.3113/FAI.2010.0828. [DOI] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Endoscopic removal of loose bodies from right posterior ankle extra-articular space. The posterolateral portal is the viewing portal. The loose bodies of the posterior ankle extra-articular space proper are removed to gain access to other parts of the posterior ankle. The small freely mobile loose bodies can be fished out by opening a hemostat or suction by an arthroscopic shaver in the extra-articular space proper. The loose body of the medial wall is peeled off and removed. The encapsulated loose bodies of the posteromedial ankle gutter are enucleated and removed. The flexor hallucis tendon is exposed and traced proximally to expose the muscle. Loose bodies around the tendon and muscle are removed. Synovial biopsy and complete synovectomy are performed. Finally, zone 2 flexor hallucis longus tendoscopy is performed through the posteromedial portal.