United States Patent 8,920,792 (US 8,920,792): Collagenase Injection for Herniated Knee Meniscus
US 8,920,792 claims a procedure that injects purified collagenase clostridium histolyticum directly into a herniated portion of the knee meniscus to “substantially break down” that tissue. The independent claim is a method claim with a defining route (direct intrameniscal injection using a needle/syringe after identifying the herniated location), the biochemical agent (collagenase clostridium histolyticum), and a therapeutic endpoint (substantial breakdown of the herniated meniscus portion). Dependent claims constrain dose volume, formulation concentration, potential excipients (calcium phosphate), and guidance modalities (ultrasound imaging and MRI-based localization).
What exactly does US 8,920,792 claim (scope and required steps)?
Claim 1: Core method
Claim 1 requires all of the following, in sequence or as part of the method:
- Patient: a human with a herniated meniscus of the knee
- Step 1: identify the location of the herniated portion
- Step 2: inject a “therapeutically effective amount” of collagenase clostridium histolyticum
- directly into the herniated meniscus tissue
- using a hypodermic needle and syringe
- Step 3/functional outcome: “substantially break down” the herniated portion
This is not a composition patent. It is a procedure with a defined target tissue, defined drug class/identity, and a defined physical delivery method (needle/syringe).
Claim 2: “substantially completely dissolves”
Claim 2 narrows the endpoint by requiring the amount to “substantially completely dissolve” the herniated meniscus tissue.
Claims 3 and 5: Dose and concentration constraints
- Claim 3: 0.5 to 1.5 cc of 0.1% solution of purified collagenase clostridium histolyticum in sterile aqueous solution
- Claim 5: 0.5 to 5.0 cc of 0.1% solution of purified collagenase clostridium histolyticum in sterile aqueous solution
These claims constrain both concentration and volume but remain broad in terms of:
- how “purified” is interpreted,
- what “sterile aqueous solution” includes (buffers, pH),
- and the duration of the procedure (single injection vs multiple administrations is not explicitly stated in the claim set you provided).
Claim 4: formulation add-on (calcium phosphate)
- Sterile aqueous solution further comprises calcium phosphate
This introduces a formulation limitation that can matter for design-around strategies.
Claims 6 to 8: imaging/guidance
- Claim 6: using imaging technology to guide the needle
- Claim 7: imaging technology comprises ultrasound
- Claim 8: location identified using an MRI imaging system
These claims cover at least two guidance paradigms:
- MRI-based localization (Claim 8)
- ultrasound-guided injection (Claim 7)
Where is the patent most enforceable: drug identity, injection route, or dose?
US 8,920,792’s strongest enforceability centers on the combination of:
1) direct intrameniscal injection,
2) collagenase clostridium histolyticum (purified),
3) treating a herniated meniscus by breaking it down.
The dependent claims add narrower constraints that can tighten infringement analysis:
- If a competitor uses a different collagenase preparation, different enzyme identity, or a different delivery route (for example, intra-articular without intrameniscal targeting), infringement risk changes materially because Claim 1 requires “directly into said herniated meniscus tissue.”
- If a competitor uses another collagenase type (or non-collagenase agents), it can avoid the specific enzyme identity required by Claim 1.
The dose claims (Claims 3 and 5) create an additional axis:
- If a competitor uses 0.1% collagenase with volumes outside the claimed ranges (for example, larger volumes for a full meniscal segment), they may avoid Claims 3/5 while still potentially infringing Claim 1 (depending on how “therapeutically effective amount” maps to their dosing).
The formulation claim (Claim 4) is likely a secondary enforcement hook:
- If a competitor uses the same concentration and volume but omits calcium phosphate, it can potentially avoid Claim 4 while still reading on other claims.
How would infringement be analyzed in practice (claim-by-claim mapping framework)?
Claim 1 infringement checklist
A product or protocol must show:
- Patient population: “human patient having a herniated meniscus of the knee”
- Localization: identification of the herniated portion’s location
- Drug: collagenase clostridium histolyticum (purified)
- Route: injection directly into herniated meniscus tissue via hypodermic needle/syringe
- Outcome: substantially break down the herniated portion
In real enforcement, the contested elements are usually:
- whether the injection site is “herniated meniscus tissue” rather than a neighboring compartment,
- whether the method includes localization sufficient to meet the “identifying the location” requirement,
- whether the administered enzyme is “collagenase clostridium histolyticum” in purified form.
Claim 2 adds a higher bar on effect
Even if a protocol breaks down collagenous structures, Claim 2 requires that the amount “substantially completely dissolves” the tissue. That raises evidentiary questions tied to imaging outcomes and histology, depending on the litigation posture.
Claims 3 and 5: volume and concentration
Infringement depends on meeting both:
- 0.1% collagenase concentration
- specified volume interval (0.5 to 1.5 cc for Claim 3; 0.5 to 5.0 cc for Claim 5)
Claim 4: calcium phosphate
A direct match requires:
- calcium phosphate present in the sterile aqueous solution
Claims 6 to 8: imaging/guidance
A competing method can still infringe Claim 1 without imaging, because Claim 1 does not require imaging. Imaging limitations only apply to those dependent claims.
- Claim 7 requires ultrasound as the imaging technology guiding the needle.
- Claim 8 requires MRI to identify the location.
What is the patent landscape likely to look like around this claim set (risk drivers and design-around paths)?
The landscape splits into two buckets:
1) Method-of-use and procedural patents for enzymatic treatment of cartilage/meniscus/ligaments (or targeted collagen breakdown).
2) Delivery and guidance patents for needle placement in musculoskeletal interventions using ultrasound or MRI.
Claim features that invite design-around
A competitor can target one or more required claim elements:
- Enzyme identity: use a different collagenase source, different bacterial collagenase, or a protease class that is not “collagenase clostridium histolyticum.”
- Targeting: inject into the joint space or a different anatomical location rather than “directly into said herniated meniscus tissue.”
- Localization: skip MRI localization and use a method that does not satisfy the “identifying the location” requirement (though Claim 1 only requires identifying the location of the herniated portion; the claim does not specify MRI for Claim 1).
- Concentration and dose window: use concentration other than 0.1% or volume outside 0.5 to 1.5 cc (Claim 3) and/or outside 0.5 to 5.0 cc (Claim 5). This may avoid the dependent claims while still potentially implicating Claim 1.
- Excipients: omit calcium phosphate to avoid Claim 4.
Claim features that strengthen enforceability
- A clear, narrow target (herniated knee meniscus) rather than a generic collagenase injection into a joint.
- A specific enzyme identity (collagenase clostridium histolyticum) and “purified” qualifier.
- Direct injection into the meniscal tissue.
How does this compare with established collagenase use in other indications (legal posture implications)?
This patent’s claims are tied to an already-known active ingredient family (collagenase clostridium histolyticum) used in other disorders. In US practice, that typically produces litigation pressure around:
- whether the meniscus application is non-obvious over prior art using the same active ingredient in other tissues, and
- whether prior art already taught direct collagenase injection into knee structures for similar outcomes.
The claim set you provided does not include a claim element like “not used for existing indications” or a special formulation mechanism beyond calcium phosphate. That can increase the obviousness challenge in validity if prior art exists that:
- identifies collagenase clostridium histolyticum for connective tissue breakdown broadly, and
- motivates intratissue injection with needle/syringe into collagen-rich orthopedic tissue.
From a business perspective, enforceability usually hinges on whether the prior art taught or suggested (i) meniscus-specific targeting and (ii) the delivery method and dosing rationale.
What does the landscape likely contain in practice: overlapping mechanistic families?
A practical mapping of “nearby” patent categories that commonly intersect with this claim set:
- Enzymatic tissue breakdown methods: patents that claim injecting collagenase-like enzymes for tissue dissolution.
- Meniscal repair or degradation: procedural patents (not necessarily enzyme-based) for meniscal tissue alteration.
- Image-guided musculoskeletal injections: patents for ultrasound guidance, MRI localization, and needle placement workflows.
- Formulation patents: specific excipients (like calcium phosphate), buffering/pH controls, and viscosity modifiers for stability and delivery.
US 8,920,792’s unique combination is the method that directly injects collagenase clostridium histolyticum into herniated meniscus tissue with defined dose/formulation constraints in dependent claims.
Critical assessment: where the claim language is tight vs where it is vulnerable
Tight elements
- “collagenase clostridium histolyticum” and “purified”
- “directly into said herniated meniscus tissue”
- “using a hypodermic needle and syringe”
- “substantially break down” (and in Claim 2: “substantially completely dissolve”)
Vulnerable/ambiguous elements (for infringement proof and validity challenges)
- “therapeutically effective amount”: without a tied clinical endpoint or dosing schedule, this can be argued broadly.
- “substantially break down” and “substantially completely dissolves”: these are outcome-based but not quantified in the claim text (no percent reduction, no imaging scale, no histological grading threshold).
- “identifying the location”: Claim 1 only requires identification, not a specific imaging system. That can be met by multiple workflow types and can broaden infringement reach, but it also makes enforcement dependent on how the prior art and competitor workflows are characterized.
Business-impact summary: what actions matter most for R&D and licensing decisions
If your strategy is freedom-to-operate (FTO)
The central risk is any protocol that does the following:
- injects collagenase clostridium histolyticum directly into herniated meniscus tissue using needle/syringe,
- with formulations at or near 0.1% and volumes within the stated ranges (for dependent claim risk),
- potentially using ultrasound or MRI workflows (for dependent claim risk).
Design-around tends to focus on:
- switching the enzyme identity,
- changing the injection target (avoid direct intrameniscal injection),
- using different concentration and/or volume,
- omitting calcium phosphate.
If your strategy is licensing or enforcement
The claim set supports enforcement based on:
- the direct injection route into meniscal tissue,
- the specific bacterial collagenase identity,
- and the expected breakdown outcome.
The dependent claims give additional leverage where dosing/formulation and imaging workflows match the claim language precisely.
Key Takeaways
- US 8,920,792 is a method-of-treatment patent centered on direct intrameniscal injection of purified collagenase clostridium histolyticum into a herniated knee meniscus after location identification.
- Claim scope is anchored by route (direct injection into herniated meniscus tissue) and enzyme identity, with dose/formulation and imaging features added in dependent claims.
- Design-around is most feasible by changing enzyme identity, injection target (avoid direct intrameniscal delivery), concentration/volume outside the dependent claim ranges, or formulation excipients (remove calcium phosphate).
- Enforceability and litigation risk likely concentrate on proving the procedural steps and matching dose/formulation precisely for the dependent claims.
FAQs
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Does US 8,920,792 cover general intra-articular injections into the knee joint?
No. Claim 1 requires injection directly into the herniated meniscus tissue.
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Is ultrasound or MRI required for infringement of Claim 1?
No. Ultrasound (Claim 7) and MRI-based location identification (Claim 8) are in dependent claims. Claim 1 only requires identifying the herniated portion’s location.
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What concentration is explicitly claimed in dependent claims?
The dependent dose claims specify 0.1% purified collagenase clostridium histolyticum in sterile aqueous solution.
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Which dependent claim includes an excipient?
Claim 4 adds calcium phosphate to the sterile aqueous solution.
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What dosing range is claimed?
Claim 3: 0.5 to 1.5 cc (of 0.1% solution). Claim 5: 0.5 to 5.0 cc (of 0.1% solution).
References
[1] United States Patent 8,920,792.
